PKIX Working Group                                   R. Housley (SPYRUS)
Internet Draft                                        W. Ford (VeriSign)
                                                          W. Polk (NIST)
                                                      D. Solo (Citicorp)
expires in six months                                      June 16, 1998


                Internet X.509 Public Key Infrastructure

                      Certificate and CRL Profile

                  <draft-ietf-pkix-ipki-part1-08.txt>


Status of this Memo

   This document is an Internet-Draft.  Internet-Drafts are working
   documents of the Internet Engineering Task Force (IETF), its areas,
   and its working groups.  Note that other groups may also distribute
   working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet- Drafts as reference
   material or to cite them other than as "work in progress."

   To learn the current status of any Internet-Draft, please check the
   "1id-abstracts.txt" listing contained in the Internet- Drafts Shadow
   Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
   munnari.oz.au Pacific Rim), ds.internic.net (US East Coast), or
   ftp.isi.edu (US West Coast).

   Copyright (C) The Internet Society (date). All Rights Reserved.


Abstract

   This is the eighth draft of the Internet Public Key Infrastructure
   X.509 Certificate and CRL Profile.  This draft is a complete
   specification.  This text includes minor modifications over the
   previous draft. This draft clarifies name encoding and comparison
   issues, updates the path validation process to conform with the
   current X.509 specification, specifies performance enhancements for
   path building, and clarifies conformance requirements.

   The Entrust patent statement in section 9.5 is a placeholder. Recent
   negotiations have produced new licensing terms; a new statement
   aligned with those terms will be inserted when available.



Housley, Ford, Polk, & Solo                                     [Page 1]


INTERNET DRAFT                                             June 16, 1998


   The key words "MUST", "REQUIRED", "SHOULD", "RECOMMENDED", and "MAY"
   in this document are to be interpreted as described in RFC 2119.

   Please send comments on this document to the ietf-pkix@tandem.com
   mail list.














































Housley, Ford, Polk, & Solo                                     [Page 2]


INTERNET DRAFT                                             June 16, 1998





                           Table of Contents



   1  Introduction ................................................    6
   2  Requirements and Assumptions ................................    7
   2.1  Communication and Topology ................................    7
   2.2  Acceptability Criteria ....................................    8
   2.3  User Expectations .........................................    8
   2.4  Administrator Expectations ................................    8
   3  Overview of Approach ........................................    8
   3.1  X.509 Version 3 Certificate ...............................   10
   3.2  Certification Paths and Trust .............................   11
   3.3  Revocation ................................................   13
   3.4  Operational Protocols .....................................   14
   3.5  Management Protocols ......................................   14
   4  Certificate and Certificate Extensions Profile ..............   15
   4.1  Basic Certificate Fields ..................................   16
   4.1.1  Certificate Fields ......................................   17
   4.1.1.1  tbsCertificate ........................................   17
   4.1.1.2  signatureAlgorithm ....................................   17
   4.1.1.3  signatureValue ........................................   18
   4.1.2  TBSCertificate ..........................................   18
   4.1.2.1  Version ...............................................   18
   4.1.2.2  Serial number .........................................   18
   4.1.2.3  Signature .............................................   19
   4.1.2.4  Issuer ................................................   19
   4.1.2.5  Validity ..............................................   21
   4.1.2.5.1  UTCTime .............................................   21
   4.1.2.5.2  GeneralizedTime .....................................   21
   4.1.2.6  Subject ...............................................   22
   4.1.2.7  Subject Public Key Info ...............................   23
   4.1.2.8  Unique Identifiers ....................................   23
   4.1.2.9 Extensions .............................................   23
   4.2  Certificate Extensions ....................................   23
   4.2.1  Standard Extensions .....................................   24
   4.2.1.1  Authority Key Identifier ..............................   25
   4.2.1.2  Subject Key Identifier ................................   25
   4.2.1.3  Key Usage .............................................   26
   4.2.1.4  Private Key Usage Period ..............................   27
   4.2.1.5  Certificate Policies ..................................   28
   4.2.1.6  Policy Mappings .......................................   30
   4.2.1.7  Subject Alternative Name ..............................   30
   4.2.1.8  Issuer Alternative Name ...............................   32
   4.2.1.9  Subject Directory Attributes ..........................   33



Housley, Ford, Polk, & Solo                                     [Page 3]


INTERNET DRAFT                                             June 16, 1998


   4.2.1.10  Basic Constraints ....................................   33
   4.2.1.11  Name Constraints .....................................   33
   4.2.1.12  Policy Constraints ...................................   35
   4.2.1.13  Extended key usage field .............................   36
   4.2.1.14  CRL Distribution Points ..............................   38
   4.2.2  Internet Certificate Extensions .........................   38
   4.2.2.1  Authority Information Access ..........................   39
   5  CRL and CRL Extensions Profile ..............................   40
   5.1  CRL Fields ................................................   41
   5.1.1  CertificateList Fields ..................................   41
   5.1.1.1  tbsCertList ...........................................   42
   5.1.1.2  signatureAlgorithm ....................................   42
   5.1.1.3  signatureValue ........................................   42
   5.1.2  Certificate List "To Be Signed" .........................   42
   5.1.2.1  Version ...............................................   42
   5.1.2.2  Signature .............................................   43
   5.1.2.3  Issuer Name ...........................................   43
   5.1.2.4  This Update ...........................................   43
   5.1.2.5  Next Update ...........................................   43
   5.1.2.6  Revoked Certificates ..................................   44
   5.1.2.7  Extensions ............................................   44
   5.2  CRL Extensions ............................................   44
   5.2.1  Authority Key Identifier ................................   45
   5.2.2  Issuer Alternative Name .................................   45
   5.2.3  CRL Number ..............................................   45
   5.2.4  Delta CRL Indicator .....................................   45
   5.2.5  Issuing Distribution Point ..............................   46
   5.3  CRL Entry Extensions ......................................   47
   5.3.1  Reason Code .............................................   47
   5.3.2  Hold Instruction Code ...................................   48
   5.3.3  Invalidity Date .........................................   48
   5.3.4  Certificate Issuer ......................................   49
   6  Certificate Path Validation .................................   49
   6.1  Basic Path Validation .....................................   50
   6.2  Extending Path Validation .................................   54
   7  Algorithm Support ...........................................   54
   7.1  One-way Hash Functions ....................................   55
   7.1.1  MD2 One-way Hash Function ...............................   55
   7.1.2  MD5 One-way Hash Function ...............................   55
   7.1.3  SHA-1 One-way Hash Function .............................   55
   7.2  Signature Algorithms ......................................   56
   7.2.1  RSA Signature Algorithm .................................   56
   7.2.2  DSA Signature Algorithm .................................   57
   7.3  Subject Public Key Algorithms .............................   58
   7.3.1  RSA Keys ................................................   58
   7.3.2  Diffie-Hellman Key Exchange Key .........................   59
   7.3.3  DSA Signature Keys ......................................   60
   8  References ..................................................   61



Housley, Ford, Polk, & Solo                                     [Page 4]


INTERNET DRAFT                                             June 16, 1998


   9  Patent Statements ...........................................   63
   9.1  Digital Signature Algorithm (DSA) .........................   64
   9.2  RSA Signature and Encryption ..............................   64
   9.3  Diffie-Hellman Key Agreement ..............................   65
   9.4  Hellman-Merkle Public Key Cryptography ....................   65
   9.5  CRL Distribution Points and Related Mechanisms ............   65
   10  Security Considerations ....................................   66
   Appendix A.  ASN.1 Structures and OIDs .........................   69
   A.1 Explicitly Tagged Module, 1988 Syntax ......................   69
   A.1 Implicitly Tagged Module, 1988 Syntax ......................   83
   Appendix B.  1993 ASN.1 Structures and OIDs ....................   90
   B.1 Explicitly Tagged Module, 1993 Syntax ......................   90
   B.2 Implicitly Tagged Module, 1993 Syntax ......................  107
   Appendix C.  ASN.1 Notes .......................................  114
   Appendix D.  Examples ..........................................  115
   D.1  Certificate ...............................................  115
   D.1.1  ASN.1 Dump of "Self-Signed" Certificate .................  116
   D.1.2  Pretty Print of "Self-Signed" Certificate ...............  118
   D.2  Certificate ...............................................  119
   D.2.1  Basic ASN.1 Dump of "End Entity" Certificate ............  119
   D.2.2  Pretty Print of "End Entity" Certificate ................  121
   D.3  End-Entity Certificate Using RSA ..........................  122
   D.4  Certificate Revocation List ...............................  127
   Appendix E.  Author Addresses ..................................  128
   Appendix F.  Full Copyright Statement ..........................  128


























Housley, Ford, Polk, & Solo                                     [Page 5]


INTERNET DRAFT                                             June 16, 1998


1  Introduction

   This specification is one part of a family of standards for the X.509
   Public Key Infrastructure (PKI) for the Internet.  This specification
   is a standalone document; implementations of this standard may
   proceed independent from the other parts.

   This specification profiles the format and semantics of certificates
   and certificate revocation lists for the Internet PKI.  Procedures
   are described for processing of certification paths in the Internet
   environment.  Encoding rules are provided for popular cryptographic
   algorithms.  Finally, ASN.1 modules are provided in the appendices
   for all data structures defined or referenced.

   The specification describes the requirements which inspire the crea-
   tion of this document and the assumptions which affect its scope in
   Section 2.  Section 3 presents an architectural model and describes
   its relationship to previous IETF and ISO/IEC/ITU standards.  In par-
   ticular, this document's relationship with the IETF PEM specifica-
   tions and the ISO/IEC/ITU X.509 documents are described.

   The specification profiles the X.509 version 3 certificate in Section
   4, and the X.509 version 2 certificate revocation list (CRL) in Sec-
   tion 5. The profiles include the identification of ISO/IEC/ITU and
   ANSI extensions which may be useful in the Internet PKI. The profiles
   are presented in the 1988 Abstract Syntax Notation One (ASN.1) rather
   than the 1994 syntax used in the ISO/IEC/ITU standards.

   This specification also includes path validation procedures in Sec-
   tion 6.  These procedures are based upon the ISO/IEC/ITU definition,
   but the presentation assumes a self-signed trusted CA certificate.
   Implementations are required to derive the same results but are not
   required to use the specified procedures.

   Section 7 of the specification describes procedures for identifica-
   tion and encoding of public key materials and digital signatures.
   Implementations are not required to use any particular cryptographic
   algorithms.  However, conforming implementations which use the iden-
   tified algorithms are required to identify and encode the public key
   materials and digital signatures as described.

   Finally, four appendices are provided to aid implementers.  Appendix
   A contains all ASN.1 structures defined or referenced within this
   specification.  As above, the material is presented in the 1988
   Abstract Syntax Notation One (ASN.1) rather than the 1994 syntax.
   Appendix B contains the same information in the 1994 ASN.1 notation
   as a service to implementers using updated toolsets.  However, Appen-
   dix A takes precedence in case of conflict.  Appendix C contains



Housley, Ford, Polk, & Solo                                     [Page 6]


INTERNET DRAFT                                             June 16, 1998


   notes on less familiar features of the ASN.1 notation used within
   this specification.  Appendix D contains examples of a conforming
   certificate and a conforming CRL.

2  Requirements and Assumptions

   The goal of this specification is to develop a profile to facilitate
   the use of X.509 certificates within Internet applications for those
   communities wishing to make use of X.509 technology. Such applica-
   tions may include WWW, electronic mail, user authentication, and
   IPsec.  In order to relieve some of the obstacles to using X.509 cer-
   tificates, this document defines a profile to promote the development
   of certificate management systems; development of application tools;
   and interoperability determined by policy.

   Some communities will need to supplement, or possibly replace, this
   profile in order to meet the requirements of specialized application
   domains or environments with additional authorization, assurance, or
   operational requirements.  However, for basic applications, common
   representations of frequently used attributes are defined so that
   application developers can obtain necessary information without
   regard to the issuer of a particular certificate or certificate revo-
   cation list (CRL).

   A certificate user should review the certificate policy generated by
   the certification authority (CA) before relying on the authentication
   or non-repudiation services associated with the public key in a par-
   ticular certificate.  To this end, this standard does not prescribe
   legally binding rules or duties.

   As supplemental authorization and attribute management tools emerge,
   such as attribute certificates, it may be appropriate to limit the
   authenticated attributes that are included in a certificate.  These
   other management tools may provide more appropriate methods of con-
   veying many authenticated attributes.

2.1  Communication and Topology

   The users of certificates will operate in a wide range of environ-
   ments with respect to their communication topology, especially users
   of secure electronic mail.  This profile supports users without high
   bandwidth, real-time IP connectivity, or high connection availabil-
   ity.  In addition, the profile allows for the presence of firewall or
   other filtered communication.

   This profile does not assume the deployment of an X.500 Directory
   system.  The profile does not prohibit the use of an X.500 Directory,
   but other means of distributing certificates and certificate



Housley, Ford, Polk, & Solo                                     [Page 7]


INTERNET DRAFT                                             June 16, 1998


   revocation lists (CRLs) may be used.

2.2  Acceptability Criteria

   The goal of the Internet Public Key Infrastructure (PKI) is to meet
   the needs of deterministic, automated identification, authentication,
   access control, and authorization functions. Support for these ser-
   vices determines the attributes contained in the certificate as well
   as the ancillary control information in the certificate such as pol-
   icy data and certification path constraints.

2.3  User Expectations

   Users of the Internet PKI are people and processes who use client
   software and are the subjects named in certificates.  These uses
   include readers and writers of electronic mail, the clients for WWW
   browsers, WWW servers, and the key manager for IPsec within a router.
   This profile recognizes the limitations of the platforms these users
   employ and the limitations in sophistication and attentiveness of the
   users themselves.  This manifests itself in minimal user configura-
   tion responsibility (e.g., trusted CA keys, rules), explicit platform
   usage constraints within the certificate, certification path con-
   straints which shield the user from many malicious actions, and
   applications which sensibly automate validation functions.

2.4  Administrator Expectations

   As with user expectations, the Internet PKI profile is structured to
   support the individuals who generally operate CAs.  Providing
   administrators with unbounded choices increases the chances that a
   subtle CA administrator mistake will result in broad compromise.
   Also, unbounded choices greatly complicate the software that must
   process and validate the certificates created by the CA.

3  Overview of Approach

   Following is a simplified view of the architectural model assumed by
   the PKIX specifications.













Housley, Ford, Polk, & Solo                                     [Page 8]


INTERNET DRAFT                                             June 16, 1998


       +---+
       | C |                       +------------+
       | e | <-------------------->| End entity |
       | r |       Operational     +------------+
       | t |       transactions          ^
       |   |      and management         |  Management
       | / |       transactions          |  transactions
       |   |                             |                PKI users
       | C |                             v
       | R |       -------------------+--+-----------+----------------
       | L |                          ^              ^
       |   |                          |              |  PKI management
       |   |                          v              |      entities
       | R |                       +------+          |
       | e | <---------------------| RA   | <---+    |
       | p |  Publish certificate  +------+     |    |
       | o |                                    |    |
       | s |                                    |    |
       | I |                                    v    v
       | t |                                +------------+
       | o | <------------------------------|     CA     |
       | r |   Publish certificate          +------------+
       | y |   Publish CRL                         ^
       |   |                                       |
       +---+                        Management     |
                                    transactions   |
                                                   v
                                               +------+
                                               |  CA  |
                                               +------+

                          Figure 1 - PKI Entities

   The components in this model are:

   end entity:  user of PKI certificates and/or end user system that
                is the subject of a certificate;
   CA:          certification authority;
   RA:          registration authority, i.e., an optional system to
                which a CA delegates certain management functions;
   repository:  a system or collection of distributed systems that
                store certificates and CRLs and serves as a means of
                distributing these certificates and CRLs to end
                entities.







Housley, Ford, Polk, & Solo                                     [Page 9]


INTERNET DRAFT                                             June 16, 1998


3.1  X.509 Version 3 Certificate

   Users of a public key must be confident that the associated private
   key is owned by the correct remote subject (person or system) with
   which an encryption or digital signature mechanism will be used.
   This confidence is obtained through the use of public key certifi-
   cates, which are data structures that bind public key values to sub-
   jects.  The binding is achieved by having a trusted CA digitally sign
   each certificate.  A certificate has a limited valid lifetime which
   is indicated in its signed contents.  Because a certificate's signa-
   ture and timeliness can be independently checked by a certificate-
   using client, certificates can be distributed via untrusted communi-
   cations and server systems, and can be cached in unsecured storage in
   certificate-using systems.

   ITU-T X.509 (formerly CCITT X.509) or ISO/IEC/ITU 9594-8, which was
   first published in 1988 as part of the X.500 Directory recommenda-
   tions, defines a standard certificate format [X.509]. The certificate
   format in the 1988 standard is called the version 1 (v1) format.
   When X.500 was revised in 1993, two more fields were added, resulting
   in the version 2 (v2) format. These two fields may be used to support
   directory access control.

   The Internet Privacy Enhanced Mail (PEM) RFCs, published in 1993,
   include specifications for a public key infrastructure based on X.509
   v1 certificates [RFC 1422].  The experience gained in attempts to
   deploy RFC 1422 made it clear that the v1 and v2 certificate formats
   are deficient in several respects.  Most importantly, more fields
   were needed to carry information which PEM design and implementation
   experience has proven necessary.  In response to these new require-
   ments, ISO/IEC/ITU and ANSI X9 developed the X.509 version 3 (v3)
   certificate format.  The v3 format extends the v2 format by adding
   provision for additional extension fields.  Particular extension
   field types may be specified in standards or may be defined and
   registered by any organization or community. In June 1996, standardi-
   zation of the basic v3 format was completed [X.509].

   ISO/IEC/ITU and ANSI X9 have also developed standard extensions for
   use in the v3 extensions field [X.509][X9.55].  These extensions can
   convey such data as additional subject identification information,
   key attribute information, policy information, and certification path
   constraints.

   However, the ISO/IEC/ITU and ANSI X9 standard extensions are very
   broad in their applicability.  In order to develop interoperable
   implementations of X.509 v3 systems for Internet use, it is necessary
   to specify a profile for use of the X.509 v3 extensions tailored for
   the Internet.  It is one goal of this document to specify a profile



Housley, Ford, Polk, & Solo                                    [Page 10]


INTERNET DRAFT                                             June 16, 1998


   for Internet WWW, electronic mail, and IPsec applications. Environ-
   ments with additional requirements may build on this profile or may
   replace it.

3.2  Certification Paths and Trust

   A user of a security service requiring knowledge of a public key gen-
   erally needs to obtain and validate a certificate containing the
   required public key.  If the public-key user does not already hold an
   assured copy of the public key of the CA that signed the certificate,
   then it might need an additional certificate to obtain that public
   key.  In general, a chain of multiple certificates may be needed,
   comprising a certificate of the public key owner (the end entity)
   signed by one CA, and zero or more additional certificates of CAs
   signed by other CAs.  Such chains, called certification paths, are
   required because a public key user is only initialized with a limited
   number of assured CA public keys.

   There are different ways in which CAs might be configured in order
   for public key users to be able to find certification paths.  For
   PEM, RFC 1422 defined a rigid hierarchical structure of CAs.  There
   are three types of PEM certification authority:

      (a)  Internet Policy Registration Authority (IPRA):  This author-
      ity, operated under the auspices of the Internet Society, acts as
      the root of the PEM certification hierarchy at level 1.  It issues
      certificates only for the next level of authorities, PCAs.  All
      certification paths start with the IPRA.

      (b)  Policy Certification Authorities (PCAs):  PCAs are at level 2
      of the hierarchy, each PCA being certified by the IPRA.  A PCA
      must establish and publish a statement of its policy with respect
      to certifying users or subordinate certification authorities.
      Distinct PCAs aim to satisfy different user needs. For example,
      one PCA (an organizational PCA) might support the general elec-
      tronic mail needs of commercial organizations, and another PCA (a
      high-assurance PCA) might have a more stringent policy designed
      for satisfying legally binding digital signature requirements.

      (c)  Certification Authorities (CAs):  CAs are at level 3 of the
      hierarchy and can also be at lower levels. Those at level 3 are
      certified by PCAs.  CAs represent, for example, particular organi-
      zations, particular organizational units (e.g., departments,
      groups, sections), or particular geographical areas.

   RFC 1422 furthermore has a name subordination rule which requires
   that a CA can only issue certificates for entities whose names are
   subordinate (in the X.500 naming tree) to the name of the CA itself.



Housley, Ford, Polk, & Solo                                    [Page 11]


INTERNET DRAFT                                             June 16, 1998


   The trust associated with a PEM certification path is implied by the
   PCA name. The name subordination rule ensures that CAs below the PCA
   are sensibly constrained as to the set of subordinate entities they
   can certify (e.g., a CA for an organization can only certify entities
   in that organization's name tree). Certificate user systems are able
   to mechanically check that the name subordination rule has been fol-
   lowed.

   The RFC 1422 uses the X.509 v1 certificate formats. The limitations
   of X.509 v1 required imposition of several structural restrictions to
   clearly associate policy information or restrict the utility of cer-
   tificates.  These restrictions included:

      (a) a pure top-down hierarchy, with all certification paths start-
      ing from IPRA;

      (b) a naming subordination rule restricting the names of a CA's
      subjects; and

      (c) use of the PCA concept, which requires knowledge of individual
      PCAs to be built into certificate chain verification logic.
      Knowledge of individual PCAs was required to determine if a chain
      could be accepted.

   With X.509 v3, most of the requirements addressed by RFC 1422 can be
   addressed using certificate extensions, without a need to restrict
   the CA structures used.  In particular, the certificate extensions
   relating to certificate policies obviate the need for PCAs and the
   constraint extensions obviate the need for the name subordination
   rule.  As a result, this document supports a more flexible architec-
   ture, including:

      (a) Certification paths may start with a public key of a CA in a
      user's own domain, or with the public key of the top of a hierar-
      chy.  Starting with the public key of a CA in a user's own domain
      has certain advantages.  In some environments, the local domain is
      the most trusted.

      (b)  Name constraints may be imposed through explicit inclusion of
      a name constraints extension in a certificate, but are not
      required.

      (c)  Policy extensions and policy mappings replace the PCA con-
      cept, which permits a greater degree of automation.  The applica-
      tion can determine if the certification path is acceptable based
      on the contents of the certificates instead of a priori knowledge
      of PCAs. This permits automation of certificate chain processing.




Housley, Ford, Polk, & Solo                                    [Page 12]


INTERNET DRAFT                                             June 16, 1998


3.3  Revocation

   When a certificate is issued, it is expected to be in use for its
   entire validity period.  However, various circumstances may cause a
   certificate to become invalid prior to the expiration of the validity
   period. Such circumstances include change of name, change of associa-
   tion between subject and CA (e.g., an employee terminates employment
   with an organization), and compromise or suspected compromise of the
   corresponding private key.  Under such circumstances, the CA needs to
   revoke the certificate.

   X.509 defines one method of certificate revocation.  This method
   involves each CA periodically issuing a signed data structure called
   a certificate revocation list (CRL).  A CRL is a time stamped list
   identifying revoked certificates which is signed by a CA and made
   freely available in a public repository.  Each revoked certificate is
   identified in a CRL by its certificate serial number. When a
   certificate-using system uses a certificate (e.g., for verifying a
   remote user's digital signature), that system not only checks the
   certificate signature and validity but also acquires a suitably-
   recent CRL and checks that the certificate serial number is not on
   that CRL.  The meaning of "suitably-recent" may vary with local pol-
   icy, but it usually means the most recently-issued CRL.  A CA issues
   a new CRL on a regular periodic basis (e.g., hourly, daily, or
   weekly).  An entry is added to the CRL as part of the next update
   following notification of revocation. An entry may be removed from
   the CRL after appearing on one regularly scheduled CRL issued beyond
   the revoked certificate's validity period.

   An advantage of this revocation method is that CRLs may be distri-
   buted by exactly the same means as certificates themselves, namely,
   via untrusted communications and server systems.

   One limitation of the CRL revocation method, using untrusted communi-
   cations and servers, is that the time granularity of revocation is
   limited to the CRL issue period.  For example, if a revocation is
   reported now, that revocation will not be reliably notified to
   certificate-using systems until the next periodic CRL is issued --
   this may be up to one hour, one day, or one week depending on the
   frequency that the CA issues CRLs.

   As with the X.509 v3 certificate format, in order to facilitate
   interoperable implementations from multiple vendors, the X.509 v2 CRL
   format needs to be profiled for Internet use.  It is one goal of this
   document to specify that profile.  However, this profile does not
   require CAs to issue CRLs. Message formats and protocols supporting
   on-line revocation notification may be defined in other PKIX specifi-
   cations.  On-line methods of revocation notification may be



Housley, Ford, Polk, & Solo                                    [Page 13]


INTERNET DRAFT                                             June 16, 1998


   applicable in some environments as an alternative to the X.509 CRL.
   On-line revocation checking may significantly reduce the latency
   between a revocation report and the distribution of the information
   to relying parties.  Once the CA accepts the report as authentic and
   valid, any query to the on-line service will correctly reflect the
   certificate validation impacts of the revocation.  However, these
   methods impose new security requirements; the certificate validator
   must trust the on-line validation service while the repository does
   not need to be trusted.

3.4  Operational Protocols

   Operational protocols are required to deliver certificates and CRLs
   (or status information) to certificate using client systems. Provi-
   sion is needed for a variety of different means of certificate and
   CRL delivery, including distribution procedures based on LDAP, HTTP,
   FTP, and X.500.  Operational protocols supporting these functions are
   defined in other PKIX specifications.  These specifications may
   include definitions of message formats and procedures for supporting
   all of the above operational environments, including definitions of
   or references to appropriate MIME content types.

3.5  Management Protocols

   Management protocols are required to support on-line interactions
   between PKI user and management entities.  For example, a management
   protocol might be used between a CA and a client system with which a
   key pair is associated, or between two CAs which cross-certify each
   other.  The set of functions which potentially need to be supported
   by management protocols include:

      (a)  registration:  This is the process whereby a user first makes
      itself known to a CA (directly, or through an RA), prior to that
      CA issuing  a certificate or certificates for that user.

      (b)  initialization:  Before a client system can operate securely
      it is necessary to install key materials which have the appropri-
      ate relationship with keys stored elsewhere in the infrastructure.
      For example, the client needs to be securely initialized with the
      public key of a trusted CA, to be used in validating certificate
      paths.  Furthermore, a client typically needs to be initialized
      with its own key pair(s).

      (c)  certification:  This  is the process in which a CA issues a
      certificate for a user's public key, and returns that certificate
      to the user's client system and/or posts that certificate in a
      repository.




Housley, Ford, Polk, & Solo                                    [Page 14]


INTERNET DRAFT                                             June 16, 1998


      (d)  key pair recovery:  As an option, user client key materials
      (e.g., a user's private key used for encryption purposes) may be
      backed up by a CA or a key backup system.  If a user needs to
      recover these backed up key materials (e.g., as a result of a for-
      gotten password or a lost key chain file), an on-line protocol
      exchange may be needed to support such recovery.

      (e)  key pair update:  All key pairs need to be updated regularly,
      i.e., replaced with a new key pair, and new certificates issued.

      (f)  revocation request:  An authorized person advises a CA of an
      abnormal situation requiring certificate revocation.

      (g)  cross-certification:  Two CAs exchange information used in
      establishing a cross-certificate. A cross-certificate is a certi-
      ficate issued by one CA to another CA which contains a CA signa-
      ture key used for issuing certificates.

   Note that on-line protocols are not the only way of implementing the
   above functions.  For all functions there are off-line methods of
   achieving the same result, and this specification does not mandate
   use of on-line protocols.  For example, when hardware tokens are
   used, many of the functions may be achieved as part of the physical
   token delivery.  Furthermore, some of the above functions may be com-
   bined into one protocol exchange.  In particular, two or more of the
   registration, initialization, and certification functions can be com-
   bined into one protocol exchange.

   The PKIX series of specifications may define a set of standard mes-
   sage formats supporting the above functions in future specifications.
   In that case, the protocols for conveying these messages in different
   environments (e.g., on-line, file transfer, e-mail, and WWW) will
   also be described in those specifications.

4  Certificate and Certificate Extensions Profile

   This section presents a profile for public key certificates that will
   foster interoperability and a reusable PKI.  This section is based
   upon the X.509 v3 certificate format and the standard certificate
   extensions defined in [X.509].  The ISO/IEC/ITU documents use the
   1993 version of ASN.1; while this document uses the 1988 ASN.1 syn-
   tax, the encoded certificate and standard extensions are equivalent.
   This section also defines private extensions required to support a
   PKI for the Internet community.

   Certificates may be used in a wide range of applications and environ-
   ments covering a broad spectrum of interoperability goals and a
   broader spectrum of operational and assurance requirements.  The goal



Housley, Ford, Polk, & Solo                                    [Page 15]


INTERNET DRAFT                                             June 16, 1998


   of this document is to establish a common baseline for generic appli-
   cations requiring broad interoperability and limited special purpose
   requirements.  In particular, the emphasis will be on supporting the
   use of X.509 v3 certificates for informal Internet electronic mail,
   IPsec, and WWW applications.

4.1  Basic Certificate Fields

   The X.509 v3 certificate basic syntax is as follows.  For signature
   calculation, the certificate is encoded using the ASN.1 distinguished
   encoding rules (DER) [X.208].  ASN.1 DER encoding is a tag, length,
   value encoding system for each element.

   Certificate  ::=  SEQUENCE  {
        tbsCertificate       TBSCertificate,
        signatureAlgorithm   AlgorithmIdentifier,
        signatureValue       BIT STRING  }

   TBSCertificate  ::=  SEQUENCE  {
        version         [0]  EXPLICIT Version DEFAULT v1,
        serialNumber         CertificateSerialNumber,
        signature            AlgorithmIdentifier,
        issuer               Name,
        validity             Validity,
        subject              Name,
        subjectPublicKeyInfo SubjectPublicKeyInfo,
        issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,
                             -- If present, version must be v2 or v3
        subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,
                             -- If present, version must be v2 or v3
        extensions      [3]  EXPLICIT Extensions OPTIONAL
                             -- If present, version must be v3
        }

   Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }

   CertificateSerialNumber  ::=  INTEGER

   Validity ::= SEQUENCE {
        notBefore      Time,
        notAfter       Time }

   Time ::= CHOICE {
        utcTime        UTCTime,
        generalTime    GeneralizedTime }

   UniqueIdentifier  ::=  BIT STRING




Housley, Ford, Polk, & Solo                                    [Page 16]


INTERNET DRAFT                                             June 16, 1998


   SubjectPublicKeyInfo  ::=  SEQUENCE  {
        algorithm            AlgorithmIdentifier,
        subjectPublicKey     BIT STRING  }

   Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension

   Extension  ::=  SEQUENCE  {
        extnID      OBJECT IDENTIFIER,
        critical    BOOLEAN DEFAULT FALSE,
        extnValue   OCTET STRING  }

   The following items describe the X.509 v3 certificate for use in the
   Internet.

4.1.1  Certificate Fields

   The Certificate is a SEQUENCE of three required fields. The fields
   are described in detail in the following subsections.

4.1.1.1  tbsCertificate

   The field contains the names of the subject and issuer, a public key
   associated with the subject, a validity period, and other associated
   information.  The fields are described in detail in section 4.1.2;
   the tbscertificate may also include extensions which are described in
   section 4.2.

4.1.1.2  signatureAlgorithm

   The signatureAlgorithm field contains the identifier for the crypto-
   graphic algorithm used by the CA to sign this certificate.  Section
   7.2 lists the supported signature algorithms.

   An algorithm identifier is defined by the following ASN.1 structure:

   AlgorithmIdentifier  ::=  SEQUENCE  {
        algorithm               OBJECT IDENTIFIER,
        parameters              ANY DEFINED BY algorithm OPTIONAL  }

   The algorithm identifier is used to identify a cryptographic algo-
   rithm.  The OBJECT IDENTIFIER component identifies the algorithm
   (such as DSA with SHA-1).  The contents of the optional parameters
   field will vary according to the algorithm identified. Section 7.2
   lists the supported algorithms for this specification.

   This field must contain the same algorithm identifier as the signa-
   ture field in the sequence tbsCertificate (see sec. 4.1.2.3).




Housley, Ford, Polk, & Solo                                    [Page 17]


INTERNET DRAFT                                             June 16, 1998


4.1.1.3  signatureValue

   The signatureValue field contains a digital signature computed upon
   the ASN.1 DER encoded tbsCertificate.  The ASN.1 DER encoded tbsCer-
   tificate is used as the input to the signature function. This signa-
   ture value is then ASN.1 encoded as a BIT STRING and included in the
   Certificate's signature field. The details of this process are speci-
   fied for each of the supported algorithms in Section 7.2.

   By generating this signature, a CA certifies the validity of the
   information in the tbsCertificate field.  In particular, the CA cer-
   tifies the binding between the public key material and the subject of
   the certificate.

4.1.2  TBSCertificate

   The sequence TBSCertificate contains information associated with the
   subject of the certificate and the CA who issued it.  Every TBSCerti-
   ficate contains the names of the subject and issuer, a public key
   associated with the subject, a validity period, a version number, and
   a serial number; some may contain optional unique identifier fields.
   The remainder of this section describes the syntax and semantics of
   these fields.  A TBSCertificate may also include extensions.  Exten-
   sions for the Internet PKI are described in Section 4.2.

4.1.2.1  Version

   This field describes the version of the encoded certificate.  When
   extensions are used, as expected in this profile, use X.509 version 3
   (value is 2).  If no extensions are present, but a UniqueIdentifier
   is present, use version 2 (value is 1).  If only basic fields are
   present, use version 1 (the value is omitted from the certificate as
   the default value).

   Implementations should be prepared to accept any version certificate.
   At a minimum, conforming implementations shall recognize version 3
   certificates.

   Generation of version 2 certificates is not expected by implementa-
   tions based on this profile.

4.1.2.2  Serial number

   The serial number is an integer assigned by the CA to each certifi-
   cate.  It must be unique for each certificate issued by a given CA
   (i.e., the issuer name and serial number identify a unique certifi-
   cate).




Housley, Ford, Polk, & Solo                                    [Page 18]


INTERNET DRAFT                                             June 16, 1998


4.1.2.3  Signature

   This field contains the algorithm identifier for the algorithm used
   by the CA to sign the certificate.

   This field must contain the same algorithm identifier as the signa-
   tureAlgorithm field in the sequence Certificate (see sec. 4.1.1.2).
   The contents of the optional parameters field will vary according to
   the algorithm identified.  Section 7.2 lists the supported signature
   algorithms.

4.1.2.4  Issuer

   The issuer field identifies the entity who has signed and issued the
   certificate.  The issuer field shall contain a non-null distinguished
   name (DN).  The issuer field is defined as the X.501 type Name.  Name
   is defined by the following ASN.1 structures:

   Name ::= CHOICE {
     RDNSequence }

   RDNSequence ::= SEQUENCE OF RelativeDistinguishedName

   RelativeDistinguishedName ::=
     SET OF AttributeTypeAndValue

   AttributeTypeAndValue ::= SEQUENCE {
     type     AttributeType,
     value    AttributeValue }

   AttributeType ::= OBJECT IDENTIFIER

   AttributeValue ::= ANY DEFINED BY AttributeType

   DirectoryString ::= CHOICE {
         teletexString           TeletexString (SIZE (1..MAX)),
         printableString         PrintableString (SIZE (1..MAX)),
         universalString         UniversalString (SIZE (1..MAX)),
         utf8String              UTF8String (SIZE (1.. MAX)),
         bmpString               BMPString (SIZE (1..MAX)) }

   The Name describes a hierarchical name composed of attributes, such
   as country name, and corresponding values, such as US.  The type of
   the component AttributeValue is determined by the AttributeType; in
   general it will be a DirectoryString.

   The DirectoryString type is defined as a choice of PrintableString,
   TeletexString, BMPString UTF8String and UniversalString.  When



Housley, Ford, Polk, & Solo                                    [Page 19]


INTERNET DRAFT                                             June 16, 1998


   creating a distinguished name, including their own, conforming CAs
   shall choose from these options as follows:

      (a) if the character set is sufficient, the string will be
      represented as a PrintableString;

      (b) failing (a), if the BMPString character set is sufficient the
      string shall be represented as a BMPString; and

      (c) failing (a) and (b), the string shall be represented as a
      UTF8String.

   The TeletexString and UniversalString are included for backward com-
   patibility, and should not be used for certificates for new subjects.
   However, these types may be used in certificates where the name was
   previously established.  Certificate users should be prepared to
   receive certificates with these string types.

   Standard sets of attributes have been defined in the X.500 series of
   specifications.  This specification recommends that issuer names con-
   tain only the following attribute types: country, organization,
   organizational-unit, distinguished name qualifier, title, locality,
   state or province name, common name (e.g., "Susan Housley"), surname,
   given name, initials, and generationqualifier (e.g., "Jr." or "IV").
   The syntax and associated object identifiers (OIDs) for these attri-
   bute types are provided in the ASN.1 modules in Appendices A and B.

   Certificate users must be prepared to process the issuer dis-
   tinguished name and subject distinguished name (see sec. 4.1.2.6)
   fields to perform name chaining for certification path validation
   (see section 6). Name chaining is performed by matching the issuer
   distinguished name in one certificate with the subject name in
   another.

   This specification requires only a subset of the name comparison
   functionality specified in X.501. The requirements for conforming
   implementations are as follows:

      (a) attribute values encoded in different string types (e.g.,
      PrintableString and BMPString) may be assumed to represent dif-
      ferent strings;

      (b) attribute values in string types other than PrintableString
      are case sensitive (this permits matching of attribute values as
      binary objects);

      (c) attribute values in PrintableString are not case sensitive
      (e.g., "Marianne Swanson" is the same as "MARIANNE SWANSON"); and



Housley, Ford, Polk, & Solo                                    [Page 20]


INTERNET DRAFT                                             June 16, 1998


      (d) attribute values in PrintableString are compared after remov-
      ing leading and trailing white space and converting internal
      strings of one or more consecutive white space characters to a
      single space.

   These name comparison rules permit a certificate user to validate
   certificates issued using languages or encodings unfamiliar to the
   certificate user.

4.1.2.5  Validity

   The certificate validity period is the time interval during which the
   CA warrants that it will maintain information about the status of the
   certificate. The field is represented as a SEQUENCE of two dates:
   the date on which the certificate validity period begins (notBefore)
   and the date on which the certificate validity period ends
   (notAfter).  Both notBefore and notAfter may be encoded as UTCTime or
   GeneralizedTime.

   CAs conforming to this profile shall always encode certificate vali-
   dity dates through the year 2049 as UTCTime; certificate validity
   dates in 2050 or later shall be encoded as GeneralizedTime.

4.1.2.5.1  UTCTime

   The universal time type, UTCTime, is a standard ASN.1 type intended
   for international applications where local time alone is not ade-
   quate.  UTCTime specifies the year through the two low order digits
   and time is specified to the precision of one minute or one second.
   UTCTime includes either Z (for Zulu, or Greenwich Mean Time) or a
   time differential.

   For the purposes of this profile, UTCTime values shall be expressed
   Greenwich Mean Time (Zulu) and shall include seconds (i.e., times are
   YYMMDDHHMMSSZ), even where the number of seconds is zero.  Conforming
   systems shall interpret the year field (YY) as follows:

      Where YY is greater than or equal to 50, the year shall be inter-
      preted as 19YY; and

      Where YY is less than 50, the year shall be interpreted as 20YY.

4.1.2.5.2  GeneralizedTime

   The generalized time type, GeneralizedTime, is a standard ASN.1 type
   for variable precision representation of time.  Optionally, the Gen-
   eralizedTime field can include a representation of the time differen-
   tial between local and Greenwich Mean Time.



Housley, Ford, Polk, & Solo                                    [Page 21]


INTERNET DRAFT                                             June 16, 1998


   For the purposes of this profile, GeneralizedTime values shall be
   expressed Greenwich Mean Time (Zulu) and shall include seconds (i.e.,
   times are YYYYMMDDHHMMSSZ), even where the number of seconds is zero.
   GeneralizedTime values shall not include fractional seconds.

4.1.2.6  Subject

   The subject field identifies the entity associated with the public
   key stored in the subject public key field.  The subject name may be
   carried in the subject field and/or the subjectAltName extension.  If
   the subject is a CA (e.g., the basic constraints extension, as dis-
   cussed in 4.2.1.10, is present and the value of cA is TRUE,) then the
   subject field must be populated with a non-null distinguished name
   matching the contents of the issuer field (see sec. 4.1.2.4) in all
   certificates issued by the subject CA.  If subject naming information
   is present only in the subjectAltName extension (e.g., a key bound
   only to an email address or URI), then the subject name must be an
   empty sequence and the subjectAltName extension must be critical.

   Where it is non-empty, the subject field shall contain an X.500 dis-
   tinguished name (DN). The DN must be unique for each subject entity
   certified by the one CA as defined by the issuer name field. (A CA
   may issue more than one certificate with the same DN to the same sub-
   ject entity.)

   The subject name field is defined as the X.501 type Name, and shall
   follow the encoding rules for the issuer name field (see sec.
   4.1.2.4). When encoding strings as the type PrintableString, conform-
   ing CAs should use mixed case but should not include leading or
   trailing white space and should limit internal white space to sub-
   strings of a single space.

   Implementations of this specification should be prepared to receive
   the following X.501 attribute types: country, organization,
   organizational-unit, distinguished name qualifier, title, locality,
   state or province name, common name (e.g., "Susan Housley"), surname,
   given name, initials, and generationqualifier (e.g., "Jr." or "IV").
   The syntax and associated object identifiers (OIDs) for these attri-
   bute types are provided in the ASN.1 modules in Appendices A and B.

   Legacy implementations exist where an RFC 822 name is embedded in the
   subject distinguished name as a PKCS #9 EmailAddress attribute [PKCS
   #9].  Conforming implementations generating new certificates with
   electronic mail addresses must use the rfc822Name in the subject
   alternative name field (see sec. 4.2.1.7) to describe such identi-
   ties.  Simultaneous inclusion of the EmailAddress attribute in the
   subject distinugished name to support legacy implementations is
   deprecated but permitted.



Housley, Ford, Polk, & Solo                                    [Page 22]


INTERNET DRAFT                                             June 16, 1998


   The ASN.1 syntax for EmailAddress and the corresponding OID are sup-
   plied below.

   EmailAddress ::= IA5String

   pkcs-9 OBJECT IDENTIFIER ::=
          { iso(1) member-body(2) US(840) rsadsi(113549) pkcs(1) 9 }

   emailAddress OBJECT IDENTIFIER ::= { pkcs-9 1 }

4.1.2.7  Subject Public Key Info

   This field is used to carry the public key and identify the algorithm
   with which the key is used. The algorithm is identified using the
   AlgorithmIdentifier structure specified in section 4.1.1.2. The
   object identifiers for the supported algorithms and the methods for
   encoding the public key materials (public key and parameters) are
   specified in section 7.3.

4.1.2.8  Unique Identifiers

   These fields may only appear if the version is 2 or 3 (see sec.
   4.1.2.1).  The subject and issuer unique identifiers are present in
   the certificate to handle the possibility of reuse of subject and/or
   issuer names over time.  This profile recommends that names not be
   reused for different entities and that Internet certificates not make
   use of unique identifiers.  CAs conforming to this profile should not
   generate certificates with unique identifiers.  Applications conform-
   ing to this profile should be capable of parsing unique identifiers
   and making comparisons.

4.1.2.9  Extensions

   This field may only appear if the version is 3 (see sec. 4.1.2.1).
   If present, this field is a SEQUENCE of one or more certificate
   extensions. The format and content of certificate extensions in the
   Internet PKI is defined in section 4.2.

4.2  Standard Certificate Extensions

   The extensions defined for X.509 v3 certificates provide methods for
   associating additional attributes with users or public keys and for
   managing the certification hierarchy.  The X.509 v3 certificate for-
   mat also allows communities to define private extensions to carry
   information unique to those communities.  Each extension in a certi-
   ficate may be designated as critical or non-critical.  A certificate
   using system must reject the certificate if it encounters a critical
   extension it does not recognize; however, a non-critical extension



Housley, Ford, Polk, & Solo                                    [Page 23]


INTERNET DRAFT                                             June 16, 1998


   may be ignored if it is not recognized.  The following sections
   present recommended extensions used within Internet certificates and
   standard locations for information.  Communities may elect to use
   additional extensions; however, caution should be exercised in adopt-
   ing any critical extensions in certificates which might prevent use
   in a general context.

   Each extension includes an OID and an ASN.1 structure.  When an
   extension appears in a certificate, the OID appears as the field
   extnID and the corresponding ASN.1 encoded structure is the value of
   the octet string extnValue.  Only one instance of a particular exten-
   sion may appear in a particular certificate. For example, a certifi-
   cate may contain only one authority key identifier extension (see
   sec. 4.2.1.1).  An extension includes the boolean critical, with a
   default value of FALSE.  The text for each extension specifies the
   acceptable values for the critical field.

   Conforming CAs are required to support key identifiers (see sec.
   4.2.1.1 and 4.2.1.2), basic constraints (see sec. 4.2.1.10), key
   usage (see sec. 4.2.1.3), and certificate policies (see sec. 4.2.1.5)
   extensions. If the CA issues certificates with an empty sequence for
   the subject field, the CA must support the subject alternative name
   extension (see sec. 4.2.1.7).  Support for the remaining extensions
   is optional. Conforming CAs may support extensions that are not iden-
   tified within this specification; certificate issuers are cautioned
   that marking such extensions as critical may inhibit interoperabil-
   ity.

   At a minimum, applications conforming to this profile shall recognize
   the extensions which shall or may be critical in this specification.
   These extensions are:  key usage (see sec. 4.2.1.3), certificate pol-
   icies (see sec. 4.2.1.5), the subject alternative name (see sec.
   4.2.1.7), basic constraints (see sec. 4.2.1.10), name constraints
   (see sec. 4.2.1.11), policy constraints (see sec. 4.2.1.12), and
   extended key usage (see sec. 4.2.1.13).

   In addition, this profile recommends application support for key
   identifiers (see sec. 4.2.1.1 and 4.2.1.2) extensions.

4.2.1  Standard Extensions

   This section identifies standard certificate extensions defined in
   [X.509] for use in the Internet PKI.  Each extension is associated
   with an OID defined in [X.509].  These OIDs are members of the certi-
   ficateExtension arc, which is defined by the following:

   certificateExtension  OBJECT IDENTIFIER ::=
                             {joint-iso-ccitt(2) ds(5) 29}



Housley, Ford, Polk, & Solo                                    [Page 24]


INTERNET DRAFT                                             June 16, 1998


   id-ce                 OBJECT IDENTIFIER ::=  certificateExtension

4.2.1.1  Authority Key Identifier

   The authority key identifier extension provides a means of identify-
   ing the public key corresponding to the private key used to sign a
   certificate. This extension is used where an issuer has multiple
   signing keys (either due to multiple concurrent key pairs or due to
   changeover).  The identification may be based on either the key iden-
   tifier (the subject key identifier in the issuer's certificate) or on
   the issuer name and serial number.

   The keyIdentifier field of the authorityKeyIdentifier extension shall
   be included in all certificates generated by conforming CAs to facil-
   itate chain building. This profile recommends support for the key
   identifier method by all certificate users.  There is one exception;
   where a CA distributes its public key in the form of a "self-signed"
   certificate, the authority key identifier may be omitted.  In this
   case, the subject and authority key identifiers would be identical.

   This extension shall not be marked critical.

   id-ce-authorityKeyIdentifier OBJECT IDENTIFIER ::=  { id-ce 35 }

   AuthorityKeyIdentifier ::= SEQUENCE {
        keyIdentifier             [0] KeyIdentifier           OPTIONAL,
        authorityCertIssuer       [1] GeneralNames            OPTIONAL,
        authorityCertSerialNumber [2] CertificateSerialNumber OPTIONAL
    }

   KeyIdentifier ::= OCTET STRING

4.2.1.2  Subject Key Identifier

   The subject key identifier extension provides a means of identifying
   the particular public key used in an application. This extension
   should be included in all certificates.

   To facilitate chain building, this extension MUST appear in all con-
   forming CA certificates, that is, all certificates including the
   basic constraints extension (see sec. 4.2.1.10) where the value of cA
   is TRUE.  The value of the subject key identifier shall be the value
   placed in the key identifier field of the Authority Key Identifier
   extension (see sec. 4.2.1.1) of certificates issued by the subject of
   this certificate.

   Where a key identifier has not been previously established, this
   specification recommends the following method for generating



Housley, Ford, Polk, & Solo                                    [Page 25]


INTERNET DRAFT                                             June 16, 1998


   keyIdentifiers:  the keyIdentifier is composed of a four bit type
   field with the value 0100 followed by the least significant 60 bits
   of the SHA-1 hash of the BIT STRING subjectPublicKey.

   This extension should be marked non-critical.

   id-ce-subjectKeyIdentifier OBJECT IDENTIFIER ::=  { id-ce 14 }

   SubjectKeyIdentifier ::= KeyIdentifier

4.2.1.3  Key Usage

   The key usage extension defines the purpose (e.g., encipherment, sig-
   nature, certificate signing) of the key contained in the certificate.
   The usage restriction might be employed when a key that could be used
   for more than one operation is to be restricted.  For example, when
   an RSA key should be used only for signing, the digitalSignature
   and/or nonRepudiation bits would be asserted. Likewise, when an RSA
   key should be used only for key management, the keyEncipherment bit
   would be asserted. When used, this extension should be marked criti-
   cal.

      id-ce-keyUsage OBJECT IDENTIFIER ::=  { id-ce 15 }

      KeyUsage ::= BIT STRING {
           digitalSignature        (0),
           nonRepudiation          (1),
           keyEncipherment         (2),
           dataEncipherment        (3),
           keyAgreement            (4),
           keyCertSign             (5),
           cRLSign                 (6),
           encipherOnly            (7),
           decipherOnly            (8) }


   Bits in the KeyUsage type are used as follows:

      The digitalSignature bit is asserted when the subject public key
      is used to verify digital signatures that have purposes other than
      non-repudiation, certificate signature, and CRL signature.  For
      example, the digitalSignature bit is asserted when the subject
      public key is used to provide authentication.

      The nonRepudiation bit is asserted when the subject public key is
      used to verify digital signatures used to provide a non-
      repudiation service which protects against the signing entity
      falsely denying some action, excluding certificate or CRL signing.



Housley, Ford, Polk, & Solo                                    [Page 26]


INTERNET DRAFT                                             June 16, 1998


      The keyEncipherment bit is asserted when the subject public key is
      used for key transport.  For example, when an RSA key is to be
      used for key management, then this bit must asserted.

      The dataEncipherment bit is asserted when the subject public key
      is used for enciphering user data, other than cryptographic keys.

      The keyAgreement bit is asserted when the subject public key is
      used for key agreement.  For example, when a Diffie-Hellman key is
      to be used for key management, then this bit must asserted.

      The keyCertSign bit is asserted when the subject public key is
      used for verifying a signature on certificates.  This bit may only
      be asserted in CA certificates.

      The cRLSign bit is asserted when the subject public key is used
      for verifying a signature on revocation information (e.g., a CRL).

      The meaning of the encipherOnly bit is undefined in the absence of
      the keyAgreement bit.  When the encipherOnly bit is asserted and
      the keyAgreement bit is also set, the subject public key may be
      used only for enciphering data while performing key agreement.

      The meaning of the decipherOnly bit is undefined in the absence of
      the keyAgreement bit.  When the decipherOnly bit is asserted and
      the keyAgreement bit is also set, the subject public key may be
      used only for deciphering data while performing key agreement.

   This profile does not restrict the combinations of bits that may be
   set in an instantiation of the keyUsage extension.  However,
   appropriate values for keyUsage extensions for particular algorithms
   are specified in section 7.3.

4.2.1.4  Private Key Usage Period

   This profile recommends against the use of this extension.  CAs con-
   forming to this profile shall not generate certificates with critical
   private key usage period extensions.

   The private key usage period extension allows the certificate issuer
   to specify a different validity period for the private key than the
   certificate. This extension is intended for use with digital signa-
   ture keys.  This extension consists of two optional components,
   notBefore and notAfter.  The private key associated with the certifi-
   cate should not be used to sign objects before or after the times
   specified by the two components, respectively. CAs conforming to this
   profile shall not generate certificates with private key usage period
   extensions unless at least one of the two components is present.



Housley, Ford, Polk, & Solo                                    [Page 27]


INTERNET DRAFT                                             June 16, 1998


   Where used, notBefore and notAfter are represented as GeneralizedTime
   and shall be specified and interpreted as defined in section
   4.1.2.5.2.

   id-ce-privateKeyUsagePeriod OBJECT IDENTIFIER ::=  { id-ce 16 }

   PrivateKeyUsagePeriod ::= SEQUENCE {
        notBefore       [0]     GeneralizedTime OPTIONAL,
        notAfter        [1]     GeneralizedTime OPTIONAL }

4.2.1.5  Certificate Policies

   The certificate policies extension contains a sequence of one or more
   policy information terms, each of which consists of an object iden-
   tifier (OID) and optional qualifiers.  These policy information terms
   indicate the policy under which the certificate has been issued and
   the purposes for which the certificate may be used.  Optional qualif-
   iers, which may be present, are not expected to change the definition
   of the policy.

   Applications with specific policy requirements are expected to have a
   list of those policies which they will accept and to compare the pol-
   icy OIDs in the certificate to that list.  If this extension is crit-
   ical, the path validation software must be able to interpret this
   extension (including the optional qualifier), or must reject the cer-
   tificate.

   To promote interoperability, this profile recommends that policy
   information terms consist of only an OID.  Where an OID alone is
   insufficient, this profile strongly recommends that use of qualifiers
   be limited to those identified in this section.

   This specification defines two policy qualifier types for use by cer-
   tificate policy writers and certificate issuers. The qualifier types
   are the CPS Pointer and User Notice qualifiers.

   The CPS Pointer qualifier contains a pointer to a Certification Prac-
   tice Statement (CPS) published by the CA.  The pointer is in the form
   of a URI.

   User notice is intended for display to a relying party when a certi-
   ficate is used.  The application software should display all user
   notices in all certificates of the certification path used, except
   that if a notice is duplicated only one copy need be displayed.  To
   prevent such duplication, this qualifier should only be present in
   end-entity certificates and CA certificates issued to other organiza-
   tions.




Housley, Ford, Polk, & Solo                                    [Page 28]


INTERNET DRAFT                                             June 16, 1998


   The user notice has two optional fields: the noticeRef field and the
   explicitText field.

      The noticeRef field, if used, names an organization and identi-
      fies, by number, a particular textual statement prepared by that
      organization.  For example, it might identify the organization
      "CertsRUs" and notice number 1.  In a typical implementation, the
      application software will have a notice file containing the
      current set of notices for CertsRUs; the application will extract
      the notice text from the file and display it.  Messages may be
      multilingual, allowing the software to select the particular
      language message for its own environment.

      An explicitText field includes the textual statement directly in
      the certificate.  The explicitText field is a string with a max-
      imum size of 200 characters.

   If both the noticeRef and explicitText options are included in the
   one qualifier and if the application software can locate the notice
   text indicated by the noticeRef option then that text should be
   displayed; otherwise, the explicitText string should be displayed.

   id-ce-certificatePolicies OBJECT IDENTIFIER ::=  { id-ce 32 }

   certificatePolicies ::= SEQUENCE SIZE (1..MAX) OF PolicyInformation

   PolicyInformation ::= SEQUENCE {
        policyIdentifier   CertPolicyId,
        policyQualifiers   SEQUENCE SIZE (1..MAX) OF
                                PolicyQualifierInfo OPTIONAL }

   CertPolicyId ::= OBJECT IDENTIFIER

   PolicyQualifierInfo ::= SEQUENCE {
        policyQualifierId  PolicyQualifierId,
        qualifier          ANY DEFINED BY policyQualifierId }

   -- policyQualifierIds for Internet policy qualifiers

   id-qt          OBJECT IDENTIFIER ::=  { id-pkix 2 }
   id-qt-cps      OBJECT IDENTIFIER ::=  { id-qt 1 }
   id-qt-unotice  OBJECT IDENTIFIER ::=  { id-qt 2 }

   PolicyQualifierId ::=
        OBJECT IDENTIFIER ( id-qt-cps | id-qt-unotice )

   Qualifier ::= CHOICE {
        cPSuri           CPSuri,



Housley, Ford, Polk, & Solo                                    [Page 29]


INTERNET DRAFT                                             June 16, 1998


        userNotice       UserNotice }

   CPSuri ::= IA5String

   UserNotice ::= SEQUENCE {
        noticeRef        NoticeReference OPTIONAL,
        explicitText     DisplayText OPTIONAL}

   NoticeReference ::= SEQUENCE {
        organization     DisplayText,
        noticeNumbers    SEQUENCE OF INTEGER }

   DisplayText ::= CHOICE {
        visibleString    VisibleString  (SIZE (1..200)),
        bmpString        BMPString      (SIZE (1..200)),
        utf8String       UTF8String     (SIZE (1..200)) }

4.2.1.6  Policy Mappings

   This extension is used in CA certificates.  It lists one or more
   pairs of OIDs; each pair includes an issuerDomainPolicy and a sub-
   jectDomainPolicy. The pairing indicates the issuing CA considers its
   issuerDomainPolicy equivalent to the subject CA's subjectDomainPol-
   icy.

   The issuing CA's users may accept an issuerDomainPolicy for certain
   applications. The policy mapping tells the issuing CA's users which
   policies associated with the subject CA are comparable to the policy
   they accept.

   This extension may be supported by CAs and/or applications, and it is
   always non-critical.

   id-ce-policyMappings OBJECT IDENTIFIER ::=  { id-ce 33 }

   PolicyMappings ::= SEQUENCE SIZE (1..MAX) OF SEQUENCE {
        issuerDomainPolicy      CertPolicyId,
        subjectDomainPolicy     CertPolicyId }

4.2.1.7  Subject Alternative Name

   The subject alternative names extension allows additional identities
   to be bound to the subject of the certificate.  Defined options
   include an Internet electronic mail address, a DNS name, an IP
   address, and a uniform resource indentifier (URI).  Other options
   exist, including completely local definitions.  Multiple name forms,
   and multiple instances of each name form, may be included.  Whenever
   such identities are to be bound into a certificate, the subject



Housley, Ford, Polk, & Solo                                    [Page 30]


INTERNET DRAFT                                             June 16, 1998


   alternative name (or issuer alternative name) extension shall be
   used.  (Note: a form of such an identifier may also be present in the
   subject distinguished name; however, the alternative name extension
   is the preferred location for finding such information.)

   Because the subject alternative name is considered to be defini-
   tiviely bound to the public key, all parts of the subject alternative
   name must be verified by the CA.

   Further, if the only subject identity included in the certificate is
   an alternative name form (e.g., an electronic mail address), then the
   subject distinguished name shall be empty (an empty sequence), and
   the subjectAltName extension shall be present. If the subject field
   contains an empty sequence, the subjectAltName extension shall be
   marked critical.

   When the subjectAltName extension contains an Internet mail address,
   the adress shall be included as an rfc822Name. The format of an
   rfc822Name is an "addr-spec" as defined in RFC 822 [RFC 822]. An
   addr-spec has the form "local-part@domain". Note that an addr-spec
   has no phrase (such as a common name) before it, has no comment (text
   surrounded in parentheses) after it, and is not surrounded by "<" and
   ">".

   When the subjectAltName extension contains a iPAddress, the address
   shall be stored in the octet string in "network byte order," as
   specified in RFC 791 [RFC 791]. The least significant bit (LSB) of
   each octet is the LSB of the corresponding byte in the network
   address. For IP Version 4, as specified in RFC 791, the octet string
   must contain exactly four octets.  For IP Version 6, as specified in
   RFC 1883, the octet string must contain exactly sixteen octets [RFC
   1883].

   When the subjectAltName extension contains a domain name service
   label, the domain name shall be stored in the dNSName (an IA5String).
   The string shall be in the "preferred name syntax," as specified by
   RFC 1034 [RFC 1034]. Note that while upper and lower case letters are
   allowed in domain names, no signifigance is attached to the case.  In
   addition, while the string " " is a legal domain name, subjectAltName
   extensions with a dNSName " " are not permitted.  Finally, the use of
   the DNS representation for Internet mail addresses (wpolk.nist.gov
   instead of wpolk@nist.gov) is not permitted; such identities are to
   be encoded as rfc822Name.

   Subject alternative names may be constrained in the same manner as
   subject distinguished names using the name constraints extension as
   described in section 4.2.1.11.




Housley, Ford, Polk, & Solo                                    [Page 31]


INTERNET DRAFT                                             June 16, 1998


   If the subjectAltName extension is present, the sequence must contain
   at least one entry.  Unlike the subject field, conforming CAs shall
   not issue certificates with subjectAltNames containing empty General-
   Name fields. For example, an rfc822Name is represented as an
   IA5String. While an empty string is a valid IA5String, such an
   rfc822Name is not permitted by this profile.  The behavior of clients
   that encounter such a certificate when processing a certificication
   path is not defined by this profile.

   Finally, the semantics of subject alternative names that include
   wildcard characters (e.g., as a placeholder for a set of names) are
   not addressed by this specification.  Applications with specific
   requirements may use such names but must define the semantics.


      id-ce-subjectAltName OBJECT IDENTIFIER ::=  { id-ce 17 }

      SubjectAltName ::= GeneralNames

      GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName

      GeneralName ::= CHOICE {
           otherName                       [0]     OtherName,
           rfc822Name                      [1]     IA5String,
           dNSName                         [2]     IA5String,
           x400Address                     [3]     ORAddress,
           directoryName                   [4]     Name,
           ediPartyName                    [5]     EDIPartyName,
           uniformResourceIdentifier       [6]     IA5String,
           iPAddress                       [7]     OCTET STRING,
           registeredID                    [8]     OBJECT IDENTIFIER}

      OtherName ::= SEQUENCE {
           type-id    OBJECT IDENTIFIER,
           value      [0] EXPLICIT ANY DEFINED BY type-id }

      EDIPartyName ::= SEQUENCE {
           nameAssigner            [0]     DirectoryString OPTIONAL,
           partyName               [1]     DirectoryString }

4.2.1.8  Issuer Alternative Names

   As with 4.2.1.7, this extension is used to associate Internet style
   identities with the certificate issuer. Issuer alternative names
   shall be encoded as in 4.2.1.7.

   Where present, this extension should not be marked critical.




Housley, Ford, Polk, & Solo                                    [Page 32]


INTERNET DRAFT                                             June 16, 1998


      id-ce-issuerAltName OBJECT IDENTIFIER ::=  { id-ce 18 }

      IssuerAltName ::= GeneralNames

4.2.1.9  Subject Directory Attributes

   The subject directory attributes extension is not recommended as an
   essential part of this profile, but it may be used in local environ-
   ments.  This extension is always non-critical.

   id-ce-subjectDirectoryAttributes OBJECT IDENTIFIER ::=  { id-ce 9 }

   SubjectDirectoryAttributes ::= SEQUENCE SIZE (1..MAX) OF Attribute

4.2.1.10  Basic Constraints

   The basic constraints extension identifies whether the subject of the
   certificate is a CA and how deep a certification path may exist
   through that CA.

   The pathLenConstraint field is meaningful only if cA is set to TRUE.
   In this case, it gives the maximum number of CA certificates that may
   follow this certificate in a certification path. A value of zero
   indicates that only an end-entity certificate may follow in the path.
   Where it appears, the pathLenConstraint field must be greater than or
   equal to zero. Where pathLenConstraint does not appear, there is no
   limit to the allowed length of the certification path.

   This extension shall appear as a critical extension in all CA certi-
   ficates.  This extension should not appear in other certificates.

   id-ce-basicConstraints OBJECT IDENTIFIER ::=  { id-ce 19 }

   BasicConstraints ::= SEQUENCE {
        cA                      BOOLEAN DEFAULT FALSE,
        pathLenConstraint       INTEGER (0..MAX) OPTIONAL }

4.2.1.11  Name Constraints

   The name constraints extension, which shall be used only in a CA cer-
   tificate, indicates a name space within which all subject names in
   subsequent certificates in a certification path must be located.
   Restrictions may apply to the subject distinguished name or subject
   alternative names.  Restrictions apply only when the specified name
   form is present. If no name of the type is in the certificate, the
   certificate is acceptable.

   Restrictions are defined in terms of permitted or excluded name



Housley, Ford, Polk, & Solo                                    [Page 33]


INTERNET DRAFT                                             June 16, 1998


   subtrees.  Any name matching a restriction in the excludedSubtrees
   field is invalid regardless of information appearing in the permit-
   tedSubtrees.  This extension must be critical.

   Within this profile, the minimum and maximum fields are not used with
   any name forms, thus minimum is always zero, and maximum is always
   absent.

   Restrictions for the rfc822 and uri name forms are all expressed in
   terms of strings with wild card matching.  An "*" is the wildcard
   character.

   For URIs, the constraint applies to the host part of the name.  Exam-
   ples would be foo.bar.com; www*.bar.com; and *.xyz.com.  When a wild-
   card appears as the leftmost subdomain, it may be matched with one or
   more subdomains.  That is, the constraint "*.xyz.com" is satisfied by
   both abc.xyz.com and abc.def.xyz.com.  However, the constraint
   "*.xyz.com" is not satisfied by "xyz.com". Otherwise, the wildcard
   may only be expanded within a single subdomain. That is, www*.bar.com
   is satisfied by www1.bar.com but not www.foo.bar.com.

   To indicate all Internet mail addresses on a particular host, the "*"
   character is used. For example, "*@xyz.com" indicates all mail
   addresses at the host "xyz.com". Note that although "*" is a valid
   character in Internet mail addresses, it is very rarely used on the
   Internet, and thus is appropriated by this specification for the
   email wildcard.

   Internet mail addresses may also be constrained by the host part of
   the name, as with URIs.  For example, "root@*.xyz.com" indicates all
   the Internet mail addresses root in the domain "xyz.com".  As above,
   "*" is a valid character in the host part of the name, but it is very
   rarely used on the Internet, and thus is appropriated by this specif-
   ication for the mail address wildcard.

   To indicate all Internet mail addresses in a particular domain, these
   mechanisms may be combined.  For example, "*@*.xyz.com" indicates all
   email addresses in the domain "xyz.com".

   DNS name restrictions are expressed as foo.bar.com. Any DNS name that
   can be constructed by simply adding to the left hand side of the name
   satisfies the name constraint. For example, www.foo.bar.com would
   satisfy the constraint but foo1.bar.com would not.

   Legacy implementations exist where an RFC 822 name is embedded in the
   subject distinguished name as a PKCS #9 e-mail attribute, which has
   the ASN.1 type EmailAddress [PKCS #9] (see sec. 4.1.2.6). When rfc822
   names are constrained, but the certificate does not include a subject



Housley, Ford, Polk, & Solo                                    [Page 34]


INTERNET DRAFT                                             June 16, 1998


   alternative name, the rfc822 name constraint must be applied to PKCS
   #9 e-mail attributes in the subject distinguished name.  The ASN.1
   syntax for EmailAddress and the corresponding OID are supplied in
   4.1.2.6.

   Restrictions of the form directoryName shall be applied to the sub-
   ject field in the certificate and to the subjectAltName extensions of
   type directoryName. Restrictions of the form x400Address shall be
   applied to subjectAltName extensions of type x400Address.

   The syntax of iPAddress shall be as described in section 4.2.1.7 with
   the following additions specifically for Name Constraints.  For IPv4
   addresses, the ipAddress field of generalName shall contain eight (8)
   octets, encoded in the style of RFC 1519 (CIDR) to represent an
   address range.  For IPv6 addresses, the ipAddress field shall contain
   32 octets similarly encoded.  For example, a name constraint for
   "class C" subnet 10.9.8.0 shall be represented as the octets 0A 09 08
   00 FF FF FF 00, representing the CIDR notation
   10.9.8.0/255.255.255.0.

   The syntax and semantics for name constraints for otherName, ediPar-
   tyName, and registeredID are not defined by this specification.

      id-ce-nameConstraints OBJECT IDENTIFIER ::=  { id-ce 30 }

      NameConstraints ::= SEQUENCE {
           permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
           excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }

      GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree

      GeneralSubtree ::= SEQUENCE {
           base                    GeneralName,
           minimum         [0]     BaseDistance DEFAULT 0,
           maximum         [1]     BaseDistance OPTIONAL }

      BaseDistance ::= INTEGER (0..MAX)

4.2.1.12  Policy Constraints

   The policy constraints extension can be used in certificates issued
   to CAs. The policy constraints extension constrains path validation
   in two ways. It can be used to prohibit policy mapping or require
   that each certificate in a path contain an acceptable policy identif-
   ier.

   If the inhibitPolicyMapping field is present, the value indicates the
   number of additional certificates that may appear in the path before



Housley, Ford, Polk, & Solo                                    [Page 35]


INTERNET DRAFT                                             June 16, 1998


   policy mapping is no longer permitted.  For example, a value of one
   indicates that policy mapping may be processed in certificates issued
   by the subject of this certificate, but not in additional certifi-
   cates in the path.

   If the requireExplicitPolicy field is present, subsequent certifi-
   cates must include an acceptable policy identifier. The value of
   requireExplicitPolicy indicates the number of additional certificates
   that may appear in the path before an explicit policy is required.
   An acceptable policy identifier is the identifier of a policy
   required by the user of the certification path or the identifier of a
   policy which has been declared equivalent through policy mapping.

   Conforming CAs shall not issue certificates where policy constraints
   is a null sequence. That is, at least one of the inhibitPolicyMapping
   field or the requireExplicitPolicy field must be present. The
   behavior of clients that encounter a null policy constraints field is
   not addressed in this profile.

   This extension may be critical or non-critical.

   id-ce-policyConstraints OBJECT IDENTIFIER ::=  { id-ce 36 }

   CertificatePoliciesSyntax ::=
                         SEQUENCE SIZE (1..MAX) OF PolicyInformation

   PolicyConstraints ::= SEQUENCE {
        requireExplicitPolicy           [0] SkipCerts OPTIONAL,
        inhibitPolicyMapping            [1] SkipCerts OPTIONAL }

   SkipCerts ::= INTEGER (0..MAX)

4.2.1.13  Extended key usage field

   This field indicates one or more purposes for which the certified
   public key may be used, in addition to or in place of the basic pur-
   poses indicated in the key usage extension field.  This field is
   defined as follows:

   id-ce-extKeyUsage OBJECT IDENTIFIER ::= {id-ce 37}

   ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId

   KeyPurposeId ::= OBJECT IDENTIFIER

   Key purposes may be defined by any organization with a need. Object
   identifiers used to identify key purposes shall be assigned in accor-
   dance with IANA or ITU-T Rec. X.660 | ISO/IEC/ITU 9834-1.



Housley, Ford, Polk, & Solo                                    [Page 36]


INTERNET DRAFT                                             June 16, 1998


   This extension may, at the option of the certificate issuer, be
   either critical or non-critical.

   If the extension is flagged critical, then the certificate shall be
   used only for one of the purposes indicated.

   If the extension is flagged non-critical, then it indicates the
   intended purpose or purposes of the key, and may be used in finding
   the correct key/certificate of an entity that has multiple
   keys/certificates. It is an advisory field and does not imply that
   usage of the key is restricted by the certification authority to the
   purpose indicated. Certificate using applications may nevertheless
   require that a particular purpose be indicated in order for the cer-
   tificate to be acceptable to that application.

   If a certificate contains both a critical key usage field and a crit-
   ical extended key usage field, then both fields shall be processed
   independently and the certificate shall only be used for a purpose
   consistent with both fields.  If there is no purpose consistent with
   both fields, then the certificate shall not be used for any purpose.

   The following key usage purposes are defined by this profile:

   id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }

   id-kp-serverAuth              OBJECT IDENTIFIER ::=   {id-kp 1}
   -- TLS Web server authentication
   -- Key usage bits that may be consistent: digitalSignature,
   --                         keyEncipherment or keyAgreement
   --
   id-kp-clientAuth              OBJECT IDENTIFIER ::=   {id-kp 2}
   -- TLS Web client authentication
   -- Key usage bits that may be consistent: digitalSignature and/or
   --                            keyAgreement
   --
   id-kp-codeSigning             OBJECT IDENTIFIER ::=   {id-kp 3}
   -- Signing of downloadable executable code
   -- Key usage bits that may be consistent: digitalSignature
   --
   id-kp-emailProtection         OBJECT IDENTIFIER ::=   {id-kp 4}
   -- E-mail protection
   -- Key usage bits that may be consistent: digitalSignature,
   --                         nonRepudiation, and/or (keyEncipherment
   --                         or keyAgreement)
   --
   id-kp-timeStamping    OBJECT IDENTIFIER ::= { id-kp 8 }
   -- Binding the hash of an object to a time from an agreed-upon time
   -- source. Key usage bits that may be consistent: digitalSignature,



Housley, Ford, Polk, & Solo                                    [Page 37]


INTERNET DRAFT                                             June 16, 1998


   --                         nonRepudiation

4.2.1.14  CRL Distribution Points

   The CRL distribution points extension identifies how CRL information
   is obtained.  The extension should be non-critical, but this profile
   recommends support for this extension by CAs and applications.
   Further discussion of CRL management is contained in section 5.

   If the cRLDistributionPoints extension contains a Distribution-
   PointName of type URI, the following semantics shall be assumed: the
   URI is a pointer to the current CRL for the associated reasons and
   will be issued by the associated cRLIssuer.  The expected values for
   the URI are those defined in 4.2.1.7. Processing rules for other
   values are not defined by this specification.  If the distribution-
   Point omits reasons, the CRL shall include revocations for all rea-
   sons. If the distributionPoint omits cRLIssuer, the CRL shall be
   issued by the CA that issued the certificate.

   id-ce-cRLDistributionPoints OBJECT IDENTIFIER ::=  { id-ce 31 }

   cRLDistributionPoints ::= {
        CRLDistPointsSyntax }

   CRLDistPointsSyntax ::= SEQUENCE SIZE (1..MAX) OF DistributionPoint

   DistributionPoint ::= SEQUENCE {
        distributionPoint       [0]     DistributionPointName OPTIONAL,
        reasons                 [1]     ReasonFlags OPTIONAL,
        cRLIssuer               [2]     GeneralNames OPTIONAL }

   DistributionPointName ::= CHOICE {
        fullName                [0]     GeneralNames,
        nameRelativeToCRLIssuer [1]     RelativeDistinguishedName }

   ReasonFlags ::= BIT STRING {
        unused                  (0),
        keyCompromise           (1),
        cACompromise            (2),
        affiliationChanged      (3),
        superseded              (4),
        cessationOfOperation    (5),
        certificateHold         (6) }

4.2.2  Private Internet Extensions

   This section defines one new extension for use in the Internet Public
   Key Infrastructure.  This extension may be used to direct



Housley, Ford, Polk, & Solo                                    [Page 38]


INTERNET DRAFT                                             June 16, 1998


   applications to identify an on-line validation service supporting the
   issuing CA.  As the information may be available in multiple forms,
   each extension is a sequence of IA5String values, each of which
   represents a URI.  The URI implicitly specifies the location and for-
   mat of the information and the method for obtaining the information.

   An object identifier is defined for the private extension.  The
   object identifier associated with the private extension is defined
   under the arc id-pe within the id-pkix name space.  Any future exten-
   sions defined for the Internet PKI will also be defined uder the arc
   id-pe.

      id-pkix  OBJECT IDENTIFIER  ::=
               { iso(1) identified-organization(3) dod(6) internet(1)
                       security(5) mechanisms(5) pkix(7) }

      id-pe  OBJECT IDENTIFIER  ::=  { id-pkix 1 }

4.2.2.1  Authority Information Access

   The authority information access extension indicates how to access CA
   information and services for the issuer of the certificate in which
   the extension appears. Information and services may include on-line
   validation services and CA policy data.  (The location of CRLs is not
   specified in this extension; that information is provided by the
   cRLDistributionPoints extension.)  This extension may be included in
   subject or CA certificates, and it is always non-critical.

   id-pe-authorityInfoAccess OBJECT IDENTIFIER ::= { id-pe 1 }

   AuthorityInfoAccessSyntax  ::=
           SEQUENCE SIZE (1..MAX) OF AccessDescription

   AccessDescription  ::=  SEQUENCE {
           accessMethod          OBJECT IDENTIFIER,
           accessLocation        GeneralName  }

   id-ad OBJECT IDENTIFIER ::= { id-pkix 48 }

   id-ad-caIssuers OBJECT IDENTIFIER ::= { id-ad 2 }

   Each entry in the sequence AuthorityInfoAccessSyntax describes the
   format and location of additional information about the CA who issued
   the certificate in which this extension appears.  The type and format
   of the information is specified by the accessMethod field; the
   accessLocation field specifies the location of the information.  The
   retrieval mechanism may be implied by the accessMethod or specified
   by accessLocation.



Housley, Ford, Polk, & Solo                                    [Page 39]


INTERNET DRAFT                                             June 16, 1998


   This profile defines one OID for accessMethod. The id-ad-caIssuers
   OID is used when the additional information lists CAs that have
   issued certificates superior to the CA that issued the certificate
   containing this extension.  The referenced CA Issuers description is
   intended to aid certificate users in the selection of a certification
   path that terminates at a point trusted by the certificate user.

   When id-ad-caIssuers appears as accessInfoType, the accessLocation
   field describes the referenced description server and the access pro-
   tocol to obtain the referenced description.  The accessLocation field
   is defined as a GeneralName, which can take several forms.  Where the
   information is available via http, ftp, or ldap, accessLocation shall
   be a uniformResourceIdentifier.  Where the information is available
   via the directory access protocol (dap), accessLocation shall be a
   directoryName. When the information is available via electronic mail,
   accessLocation shall be an rfc822Name.  The semantics of other name
   forms of accessLocation (when accessMethod is id-ad-caIssuers) are
   not defined by this specification.

   Additional access descriptors may be defined in other PKIX specifica-
   tions.

5  CRL and CRL Extensions Profile

   As described above, one goal of this X.509 v2 CRL profile is to
   foster the creation of an interoperable and reusable Internet PKI.
   To achieve this goal, guidelines for the use of extensions are speci-
   fied, and some assumptions are made about the nature of information
   included in the CRL.

   CRLs may be used in a wide range of applications and environments
   covering a broad spectrum of interoperability goals and an even
   broader spectrum of operational and assurance requirements.  This
   profile establishes a common baseline for generic applications
   requiring broad interoperability.  The profile defines a baseline set
   of information that can be expected in every CRL.  Also, the profile
   defines common locations within the CRL for frequently used attri-
   butes as well as common representations for these attributes.

   This profile does not define any private Internet CRL extensions or
   CRL entry extensions.

   Environments with additional or special purpose requirements may
   build on this profile or may replace it.

   Conforming CAs are not required to issue CRLs if other revocation or
   certificate status mechanisms are provided.  Conforming CAs that
   issue CRLs are required to issue version 2 CRLs, and CAs must include



Housley, Ford, Polk, & Solo                                    [Page 40]


INTERNET DRAFT                                             June 16, 1998


   the date by which the next CRL will be issued in the nextUpdate field
   (see sec. 5.1.2.5).  Conforming applications are required to process
   version 1 and 2 CRLs.

5.1  CRL Fields

   The X.509 v2 CRL syntax is as follows.  For signature calculation,
   the data that is to be signed is ASN.1 DER encoded.  ASN.1 DER encod-
   ing is a tag, length, value encoding system for each element.

   CertificateList  ::=  SEQUENCE  {
        tbsCertList          TBSCertList,
        signatureAlgorithm   AlgorithmIdentifier,
        signatureValue       BIT STRING  }

   TBSCertList  ::=  SEQUENCE  {
        version                 Version OPTIONAL,
                                     -- if present, must be v2
        signature               AlgorithmIdentifier,
        issuer                  Name,
        thisUpdate              Time,
        nextUpdate              Time OPTIONAL,
        revokedCertificates     SEQUENCE OF SEQUENCE  {
             userCertificate         CertificateSerialNumber,
             revocationDate          Time,
             crlEntryExtensions      Extensions OPTIONAL
                                           -- if present, must be v2
                                  }  OPTIONAL,
        crlExtensions           [0]  EXPLICIT Extensions OPTIONAL
                                           -- if present, must be v2
                                  }

   -- Version, Time, CertificateSerialNumber, and Extensions
   -- are all defined in the ASN.1 in section 4.1

   -- AlgorithmIdentifier is defined in section 4.1.1.2

   The following items describe the use of the X.509 v2 CRL in the
   Internet PKI.

5.1.1  CertificateList Fields

   The CertificateList is a SEQUENCE of three required fields. The
   fields are described in detail in the following subsections.







Housley, Ford, Polk, & Solo                                    [Page 41]


INTERNET DRAFT                                             June 16, 1998


5.1.1.1  tbsCertList

   The first field in the sequence is the tbsCertList.  This field is
   itself a sequence containing the name of the issuer, issue date,
   issue date of the next list, the list of revoked certificates, and
   optional CRL extensions.  Further, each entry on the revoked certifi-
   cate list is defined by a sequence of user certificate serial number,
   revocation date, and optional CRL entry extensions.

5.1.1.2  signatureAlgorithm

   The signatureAlgorithm field contains the algorithm identifier for
   the algorithm used by the CA to sign the CertificateList.  The field
   is of type AlgorithmIdentifier, which is defined in section 4.1.1.2.
   Section 7.2 lists the supported algorithms for this specification.
   Conforming CAs shall use the algorithm identifiers presented in sec-
   tion 7.2 when signing with a supported signature algorithm.

   This field must contain the same algorithm identifier as the signa-
   ture field in the sequence tbsCertList (see sec. 5.1.2.2).

5.1.1.3  signatureValue

   The signatureValue field contains a digital signature computed upon
   the ASN.1 DER encoded tbsCertList.  The ASN.1 DER encoded tbsCertList
   is used as the input to the signature function. This signature value
   is then ASN.1 encoded as a BIT STRING and included in the CRL's sig-
   natureValue field. The details of this process are specified for each
   of the supported algorithms in section 7.2.

5.1.2  Certificate List "To Be Signed"

   The certificate list to be signed, or TBSCertList, is a SEQUENCE of
   required and optional fields.  The required fields identify the CRL
   issuer, the algorithm used to sign the CRL, the date and time the CRL
   was issued, and the date and time by which the CA will issue the next
   CRL.

   Optional fields include lists of revoked certificates and CRL exten-
   sions.  The revoked certificate list is optional to support the case
   where a CA has not revoked any unexpired certificates that it has
   issued.  The profile requires conforming CAs to use the CRL extension
   cRLNumber in all CRLs issued.

5.1.2.1  Version

   This optional field describes the version of the encoded CRL.  When
   extensions are used, as required by this profile, this field shall be



Housley, Ford, Polk, & Solo                                    [Page 42]


INTERNET DRAFT                                             June 16, 1998


   present and shall specify version 2 (the integer value is 1).

5.1.2.2  Signature

   This field contains the algorithm identifier for the algorithm used
   to sign the CRL.  Section 7.2 lists OIDs for the most popular signa-
   ture algorithms used in the Internet PKI.

   This field must contain the same algorithm identifier as the signa-
   tureAlgorithm field in the sequence CertificateList (see section
   5.1.1.2).

5.1.2.3  Issuer Name

   The issuer name identifies the entity who has signed and issued the
   CRL.  The issuer identity is carried in the issuer name field. Alter-
   native name forms may also appear in the issuerAltName extension (see
   sec. 5.2.2).  The issuer name field shall contain an X.500 dis-
   tinguished name (DN).  The issuer name field is defined as the X.501
   type Name, and shall follow the encoding rules for the issuer name
   field in the certificate (see sec. 4.1.2.4).

5.1.2.4  This Update

   This field indicates the issue date of this CRL. ThisUpdate may be
   encoded as UTCTime or GeneralizedTime.

   CAs conforming to this profile that issue CRLs shall encode thisUp-
   date as UTCTime for dates through the year 2049. CAs conforming to
   this profile that issue CRLs shall encode thisUpdate as Generalized-
   Time for dates in the year 2050 or later.

   Where encoded as UTCTime, thisUpdate shall be specified and inter-
   preted as defined in section 4.1.2.5.1.  Where encoded as General-
   izedTime, thisUpdate shall be specified and interpreted as defined in
   section 4.1.2.5.2.

5.1.2.5  Next Update

   This field indicates the date by which the next CRL will be issued.
   The next CRL could be issued before the indicated date, but it will
   not be issued any later than the indicated date. nextUpdate may be
   encoded as UTCTime or GeneralizedTime.

   This profile requires inclusion of nextUpdate in all CRLs issued by
   conforming CAs. Note that the ASN.1 syntax of TBSCertList describes
   this field as OPTIONAL, which is consistent with the ASN.1 structure
   defined in [X.509]. The behavior of clients processing CRLs which



Housley, Ford, Polk, & Solo                                    [Page 43]


INTERNET DRAFT                                             June 16, 1998


   omit nextUpdate is not specified by this profile.

   CAs conforming to this profile that issue CRLs shall encode nextUp-
   date as UTCTime for dates through the year 2049. CAs conforming to
   this profile that issue CRLs shall encode nextUpdate as Generalized-
   Time for dates in the year 2050 or later.

   Where encoded as UTCTime, nextUpdate shall be specified and inter-
   preted as defined in section 4.1.2.5.1.  Where encoded as General-
   izedTime, nextUpdate shall be specified and interpreted as defined in
   section 4.1.2.5.2.

5.1.2.6  Revoked Certificates

   Revoked certificates are listed.  The revoked certificates are named
   by their serial numbers.  Certificates are uniquely identified by the
   combination of the issuer name or issuer alternative name along with
   the user certificate serial number.  The date on which the revocation
   occurred is specified.  The time for revocationDate shall be
   expressed as described in section 5.1.2.4. Additional information may
   be supplied in CRL entry extensions; CRL entry extensions are dis-
   cussed in section 5.3.

5.1.2.7  Extensions

   This field may only appear if the version is 2 (see sec. 5.1.2.1).
   If present, this field is a SEQUENCE of one or more CRL extensions.
   CRL extensions are discussed in section 5.2.

5.2  CRL Extensions

   The extensions defined by ANSI X9 and ISO/IEC/ITU for X.509 v2 CRLs
   [X.509] [X9.55] provide methods for associating additional attributes
   with CRLs.  The X.509 v2 CRL format also allows communities to define
   private extensions to carry information unique to those communities.
   Each extension in a CRL may be designated as critical or non-
   critical.  A CRL validation must fail if it encounters a critical
   extension which it does not know how to process.  However, an
   unrecognized non-critical extension may be ignored.  The following
   subsections present those extensions used within Internet CRLs.  Com-
   munities may elect to include extensions in CRLs which are not
   defined in this specification. However, caution should be exercised
   in adopting any critical extensions in CRLs which might be used in a
   general context.

   Conforming CAs that issue CRLs are required to include the authority
   key identifier (see sec. 5.2.1) and the CRL number (see sec. 5.2.3)
   extensions in all CRLs issued.



Housley, Ford, Polk, & Solo                                    [Page 44]


INTERNET DRAFT                                             June 16, 1998


5.2.1  Authority Key Identifier

   The authority key identifier extension provides a means of identify-
   ing the public key corresponding to the private key used to sign a
   CRL.  The identification can be based on either the key identifier
   (the subject key identifier in the CRL signer's certificate) or on
   the issuer name and serial number. This extension is especially use-
   ful where an issuer has more than one signing key, either due to mul-
   tiple concurrent key pairs or due to changeover.

   Conforming CAs shall use the key identifier method, and shall include
   this extension in all CRLs issued.

   The syntax for this CRL extension is defined in section 4.2.1.1.

5.2.2  Issuer Alternative Name

   The issuer alternative names extension allows additional identities
   to be associated with the issuer of the CRL.  Defined options include
   an rfc822 name (electronic mail address), a DNS name, an IP address,
   and a URI.  Multiple instances of a name and multiple name forms may
   be included.  Whenever such identities are used, the issuer alterna-
   tive name extension shall be used.

   The issuerAltName extension should not be marked critical.

   The OID and syntax for this CRL extension are defined in section
   4.2.1.8.

5.2.3  CRL Number

   The CRL number is a non-critical CRL extension which conveys a mono-
   tonically increasing sequence number for each CRL issued by a CA.
   This extension allows users to easily determine when a particular CRL
   supersedes another CRL.  CAs conforming to this profile shall include
   this extension in all CRLs.

   id-ce-cRLNumber OBJECT IDENTIFIER ::= { id-ce 20 }

   cRLNumber ::= INTEGER (0..MAX)

5.2.4  Delta CRL Indicator

   The delta CRL indicator is a critical CRL extension that identifies a
   delta-CRL.  The use of delta-CRLs can significantly improve process-
   ing time for applications which store revocation information in a
   format other than the CRL structure.  This allows changes to be added
   to the local database while ignoring unchanged information that is



Housley, Ford, Polk, & Solo                                    [Page 45]


INTERNET DRAFT                                             June 16, 1998


   already in the local database.

   When a delta-CRL is issued, the CAs shall also issue a complete CRL.

   The value of BaseCRLNumber identifies the CRL number of the base CRL
   that was used as the starting point in the generation of this delta-
   CRL.  The delta-CRL contains the changes between the base CRL and the
   current CRL issued along with the delta-CRL.  It is the decision of a
   CA as to whether to provide delta-CRLs.  Again, a delta-CRL shall not
   be issued without a corresponding complete CRL.  The value of
   CRLNumber for both the delta-CRL and the corresponding complete CRL
   shall be identical.

   A CRL user constructing a locally held CRL from delta-CRLs shall con-
   sider the constructed CRL incomplete and unusable if the CRLNumber of
   the received delta-CRL is more that one greater that the CRLnumber of
   the delta-CRL last processed.

   id-ce-deltaCRLIndicator OBJECT IDENTIFIER ::= { id-ce 27 }

   deltaCRLIndicator ::= BaseCRLNumber

   BaseCRLNumber ::= CRLNumber

5.2.5  Issuing Distribution Point

   The issuing distribution point is a critical CRL extension that iden-
   tifies the CRL distribution point for a particular CRL, and it indi-
   cates whether the CRL covers revocation for end entity certificates
   only, CA  certificates only, or a limitied set of reason codes.
   Although the extension is critical, conforming implementations are
   not required to support this extension.

   The CRL is signed using the CA's private key.  CRL Distribution
   Points do not have their own key pairs.  If the CRL is stored in the
   X.500 Directory, it is stored in the Directory entry corresponding to
   the CRL distribution point, which may be different than the Directory
   entry of the CA.

   CAs may use CRL distribution points to partition the CRL on the basis
   of compromise and routine revocation.  In this case, the revocations
   with reason code keyCompromise (1) shall appear in one distribution
   point, and the revocations with other reason codes shall appear in
   another distribution point. The reason codes associated with a dis-
   tribution point must be specified in onlySomeReasons. If onlySomeRea-
   sons does not appear, the distribution point must contain revocations
   for all reason codes.




Housley, Ford, Polk, & Solo                                    [Page 46]


INTERNET DRAFT                                             June 16, 1998


   Where the issuingDistributionPoint extension contains a URL, the fol-
   lowing semantics shall be assumed: the object is a pointer to the
   most current CRL issued by this CA.  The URI schemes ftp, http,
   mailto [RFC1738] and ldap [RFC1778] are defined for this purpose.
   The URI must be an absolute, not relative, pathname and must specify
   the host.

   id-ce-issuingDistributionPoint OBJECT IDENTIFIER ::= { id-ce 28 }

   issuingDistributionPoint ::= SEQUENCE {
        distributionPoint       [0] DistributionPointName OPTIONAL,
        onlyContainsUserCerts   [1] BOOLEAN DEFAULT FALSE,
        onlyContainsCACerts     [2] BOOLEAN DEFAULT FALSE,
        onlySomeReasons         [3] ReasonFlags OPTIONAL,
        indirectCRL             [4] BOOLEAN DEFAULT FALSE }

5.3  CRL Entry Extensions

   The CRL entry extensions already defined by ANSI X9 and ISO/IEC/ITU
   for X.509 v2 CRLs provide methods for associating additional attri-
   butes with CRL entries [X.509] [X9.55].  The X.509 v2 CRL format also
   allows communities to define private CRL entry extensions to carry
   information unique to those communities.  Each extension in a CRL
   entry may be designated as critical or non-critical.  A CRL valida-
   tion must fail if it encounters a critical CRL entry extension which
   it does not know how to process.  However, an unrecognized non-
   critical CRL entry extension may be ignored.  The following subsec-
   tions present recommended extensions used within Internet CRL entries
   and standard locations for information.  Communities may elect to use
   additional CRL entry extensions; however, caution should be exercised
   in adopting any critical extensions in CRL entries which might be
   used in a general context.

   All CRL entry extensions used in this specification are non-critical.
   Support for these extensions is optional for conforming CAs and
   applications.  However, CAs that issue CRLs are strongly encouraged
   to include reason codes (see sec. 5.3.1) and invalidity dates (see
   sec. 5.3.3) whenever this information is available.

5.3.1  Reason Code

   The reasonCode is a non-critical CRL entry extension that identifies
   the reason for the certificate revocation. CAs are strongly
   encouraged to include meaningful reason codes in CRL entries; how-
   ever, the reason code CRL entry extension should be absent instead of
   using the unspecified (0) reasonCode value.

   id-ce-cRLReason OBJECT IDENTIFIER ::= { id-ce 21 }



Housley, Ford, Polk, & Solo                                    [Page 47]


INTERNET DRAFT                                             June 16, 1998


   -- reasonCode ::= { CRLReason }

   CRLReason ::= ENUMERATED {
        unspecified             (0),
        keyCompromise           (1),
        cACompromise            (2),
        affiliationChanged      (3),
        superseded              (4),
        cessationOfOperation    (5),
        certificateHold         (6),
        removeFromCRL           (8) }

5.3.2  Hold Instruction Code

   The hold instruction code is a non-critical CRL entry extension that
   provides a registered instruction identifier which indicates the
   action to be taken after encountering a certificate that has been
   placed on hold.

   id-ce-holdInstructionCode OBJECT IDENTIFIER ::= { id-ce 23 }

   holdInstructionCode ::= OBJECT IDENTIFIER

   The following instruction codes have been defined.  Conforming appli-
   cations that process this extension shall recognize the following
   instruction codes.

   holdInstruction    OBJECT IDENTIFIER ::=
                    { iso(1) member-body(2) us(840) x9-57(10040) 2 }

   id-holdinstruction-none   OBJECT IDENTIFIER ::= {holdInstruction 1}
   id-holdinstruction-callissuer
                             OBJECT IDENTIFIER ::= {holdInstruction 2}
   id-holdinstruction-reject OBJECT IDENTIFIER ::= {holdInstruction 3}

   Conforming applications which encounter an id-holdinstruction-
   callissuer must call the certificate issuer or reject the certifi-
   cate.  Conforming applications which encounter an id-
   holdinstruction-reject shall reject the certificate. The hold
   instruction id-holdinstruction-none is semantically equivalent to the
   absence of a holdInstructionCode, and its use is strongly deprecated
   for the Internet PKI.

5.3.3  Invalidity Date

   The invalidity date is a non-critical CRL entry extension that pro-
   vides the date on which it is known or suspected that the private key
   was compromised or that the certificate otherwise became invalid.



Housley, Ford, Polk, & Solo                                    [Page 48]


INTERNET DRAFT                                             June 16, 1998


   This date may be earlier than the revocation date in the CRL entry,
   which is the date at which the CA processed the revocation. When a
   revocation is first posted by a CA in a CRL, the invalidity date may
   precede the date of issue of earlier CRLs, but the revocation date
   should not precede the date of issue of earlier CRLs.  Whenever this
   information is available, CAs are strongly encouraged to share it
   with CRL users.

   The GeneralizedTime values included in this field shall be expressed
   in Greenwich Mean Time (Zulu), and shall be specified and interpreted
   as defined in section 4.1.2.5.2.

   id-ce-invalidityDate OBJECT IDENTIFIER ::= { id-ce 24 }

   invalidityDate ::=  GeneralizedTime

5.3.4  Certificate Issuer

   This CRL entry extension identifies the certificate issuer associated
   with an entry in an indirect CRL, i.e. a CRL that has the indirectCRL
   indicator set in its issuing distribution point extension. If this
   extension is not present on the first entry in an indirect CRL, the
   certificate issuer defaults to the CRL issuer. On subsequent entries
   in an indirect CRL, if this extension is not present, the certificate
   issuer for the entry is the same as that for the preceding entry.
   This field is defined as follows:

   id-ce-certificateIssuer   OBJECT IDENTIFIER ::= { id-ce 29 }

   certificateIssuer ::=     GeneralNames

   If used by conforming CAs that issue CRLs, this extension is always
   critical.  If an implementation ignored this extension it could not
   correctly attribute CRL entries to certificates.  This specification
   recommends that implementations recognize this extension.

6  Certification Path Validation

   Certification path validation procedures for the Internet PKI are
   based on section 12.4.3 of [X.509].  Certification path processing
   verifies the binding between the subject distinguished name and/or
   subject alternative name and subject public key.  The binding is lim-
   ited by constraints which are specified in the certificates which
   comprise the path. The basic constraints and policy constraints
   extensions allow the certification path processing logic to automate
   the decision making process.

   This section describes an algorithm for validating certification



Housley, Ford, Polk, & Solo                                    [Page 49]


INTERNET DRAFT                                             June 16, 1998


   paths.  Conforming implementations of this specification are not
   required to implement this algorithm, but shall be functionally
   equivalent to the external behaviour resulting from this procedure.
   Any algorithm may be used by a particular implementation so long as
   it derives the correct result.

   In section 6.1, the text describes basic path validation. This text
   assumes that all valid paths begin with certificates issued by a sin-
   gle "most-trusted CA". The algorithm requires the public key of the
   CA, the CA's name, the validity period of the public key, and any
   constraints upon the set of paths which may be validated using this
   key.

   The "most-trusted CA" is a matter of policy: it could be a root CA in
   a hierarchical PKI; the CA that issued the verifier's own
   certificate(s); or any other CA in a network PKI.  The path valida-
   tion procedure is the same regardless of the choice of "most-trusted
   CA."

   section 6.2 describes extensions to the basic path validation algo-
   rithm. Two specific cases are discussed: the case where paths may
   begin with one of several trusted CAs; and where compatibility with
   the PEM architecture is required.

   6.1 Basic Path Validation

   The text assumes that the trusted public key (and related informa-
   tion) is contained in a "self-signed" certificate. This simplifies
   the description of the path processing procedure.  Note that the sig-
   nature on the self-signed certificate does not provide any security
   services.  The public key it contains is trusted because of other
   procedures used to obtain and protect it.

   The goal of path validation is to verify the binding between a sub-
   ject distinguished name or subject alternative name and subject pub-
   lic key, as represented in the "end entity" certificate, based on the
   public key of the "most-trusted CA".  This requires obtaining a
   sequence of certificates that support that binding.  The procedures
   performed to obtain this sequence is outside the scope of this sec-
   tion.

   The following text also assumes that certificates do not use subject
   or unique identifier fields or private critical extensions, as recom-
   mended within this profile.  However, if these components appear in
   certificates, they must be processed.  Finally, policy qualifiers are
   also neglected for the sake of clarity.

   A certification path is a sequence of n certificates where:



Housley, Ford, Polk, & Solo                                    [Page 50]


INTERNET DRAFT                                             June 16, 1998


      * for all x in {1,(n-1)}, the subject of certificate x is the
      issuer of certificate x+1.
      * certificate x=1 is the the self-signed certificate, and
      * certificate x=n is the end entity certificate.

   This section assumes the following inputs are provided to the path
   processing logic:

      (a)  a certification path of length n;

      (b)  a set of initial policy identifiers (each comprising a
      sequence of policy element identifiers), which identifies one or
      more certificate policies, any one of which would be acceptable
      for the purposes of certification path processing, or the special
      value "any-policy";

      (c)  the current date/time (if not available internally to the
      certification path processing module); and

      (d)  the time, T, for which the validity of the path should be
      determined.  (This may be the current date/time, or some point in
      the past.)

   From the inputs, the procedure intializes five state variables:

      (a)  acceptable policy set:  A set of certificate policy identif-
      iers comprising the policy or policies recognized by the public
      key user together with policies deemed equivalent through policy
      mapping. The initial value of the acceptable policy set is the
      special value "any-policy".

      (b)  constrained subtrees:  A set of root names defining a set of
      subtrees within which all subject names in subsequent certificates
      in the certification path shall fall. The initial value is
      "unbounded".

      (c)  excluded subtrees:  A set of root names defining a set of
      subtrees within which no subject name in subsequent certificates
      in the certification path may fall. The initial value is "empty".

      (d)  explicit policy: an integer which indicates if an explicit
      policy identifier is required. The integer indicates the first
      certificate in the path where this requirement is imposed. Once
      set, this variable may be decreased, but may not be increased.
      (That is, if a certificate in the path requires explicit policy
      identifiers, a later certificate can not remove this requirement.)
      The initial value is n+1.




Housley, Ford, Polk, & Solo                                    [Page 51]


INTERNET DRAFT                                             June 16, 1998


      (e)  policy mapping: an integer which indicates if policy mapping
      is permitted.  The integer indicates the last certificate on which
      policy mapping may be applied.  Once set, this variable may be
      decreased, but may not be increased. (That is, if a certificate in
      the path specifies policy mapping is not permitted, it can not be
      overriden by a later certificate.) The initial value is n+1.

   The actions performed by the path processing software for each certi-
   ficate i=1 through n are described below.  The self-signed certifi-
   cate is certificate i=1, the end entity certificate is i=n. The pro-
   cessing is performed sequentially, so that processing certificate i
   affects the state variables for processing certificate (i+1). Note
   that actions (h) through (m) are not applied to the end entity certi-
   ficate (certificate n).

   The path processing actions to be performed are:

      (a)  Verify the basic certificate information, including:

         (1) the certificate was signed using the subject public key
         from certificate i-1 (in the special case i=1, this step may be
         omitted; if not, use the subject public key from the same cer-
         tificate),

         (2) the certificate validity period includes time T,

         (3) the certificate had not been revoked at time T and is not
         currently on hold status that commenced before time T, (this
         may be determined by obtaining the appropriate CRL or status
         information, or by out-of-band mechanisms), and

         (4) the subject and issuer names chain correctly (that is, the
         issuer of this certificate was the subject of the previous cer-
         tificate.)  If the certificate has an empty sequence in the
         name field, name chaining will use the critical subjectAltNames
         and issuerAltNames fields.

      (b)  Verify that the subject name and subjectAltName extension
      (critical or noncritical) is consistent with the constrained sub-
      trees state variables.

      (c)  Verify that the subject name and subjectAltName extension
      (critical or noncritical) is consistent with the excluded subtrees
      state variables.

      (d)  Verify that policy information is consistent with the initial
      policy set:




Housley, Ford, Polk, & Solo                                    [Page 52]


INTERNET DRAFT                                             June 16, 1998


         (1) if the explicit policy state variable is less than or equal
         to i, a policy identifier in the certificate must be in the
         initial policy set; and

         (2) if the policy mapping variable is less than or equal to i,
         the policy identifier may not be mapped.

      (e)  Verify that policy information is consistent with the accept-
      able policy set:

         (1) if the certificate policies extension is marked critical,
         the intersection of the policies extension and the acceptable
         policy set must be non-null;

         (2) the acceptable policy set is assigned the resulting inter-
         section as its new value.

      (g) Verify that the intersection of the acceptable policy set and
      the initial policy set is non-null.

      (h)  Recognize and process any other critical extension present in
      the certificate.

      (i) Verify that the certificate is a CA certificate (as specified
      in a basicConstraints extension or as verified out-of-band).

      (j)  If permittedSubtrees is present in the certificate, set the
      constrained subtrees state variable to the intersection of its
      previous value and the value indicated in the extension field.

      (k)  If excludedSubtrees is present in the certificate, set the
      excluded subtrees state variable to the union of its previous
      value and the value indicated in the extension field.

      (l)  If a policy constraints extension is included in the certifi-
      cate, modify the explicit policy and policy mapping state vari-
      ables as follows:

         (1) If requireExplicitPolicy is present and has value r, the
         explicit policy state variable is set to the minimum of its
         current value and the sum of r and i (the current certificate
         in the sequence).

         (2) If inhibitPolicyMapping is present and has value q, the
         policy mapping state variable is set to the minimum of its
         current value and the sum of q and i (the current certificate
         in the sequence).




Housley, Ford, Polk, & Solo                                    [Page 53]


INTERNET DRAFT                                             June 16, 1998


      (m) If a key usage extension is marked critical, ensure the key-
      CertSign bit is set.

   If any one of the above checks fail, the procedure terminates,
   returning a failure indication and an appropriate reason.  If none of
   the above checks fail on the end-entity certificate, the procedure
   terminates, returning a success indication together with the set of
   all policy qualifier values encountered in the set of certificates.

   6.2 Extending Path Validation

   The path validation algorithm presented in 6.1 is based on several
   simplifying assumptions (e.g., a single trusted CA that starts all
   valid paths). This algorithm may be extended for cases where the
   assumptions do not hold.

   This procedure may be extended for multiple trusted CAs by providing
   a set of self-signed certificates to the validation module.  In this
   case, a valid path could begin with any one of the self-signed certi-
   ficates.  Limitations in the trust paths for any particular key may
   be incorporated into the self-signed certificate's extensions. In
   this way, the self-signed certificates permit the path validation
   module to automatically incorporate local security policy and
   requirements.

   It is also possible to specify an extended version of the above cer-
   tification path processing procedure which results in default
   behaviour identical to the rules of PEM [RFC 1422].  In this extended
   version, additional inputs to the procedure are a list of one or more
   Policy Certification Authorities (PCAs) names and an indicator of the
   position in the certification path where the PCA is expected.  At the
   nominated PCA position, the CA name is compared against this list.
   If a recognized PCA name is found, then a constraint of Subordina-
   teToCA is implicitly assumed for the remainder of the certification
   path and processing continues.  If no valid PCA name is found, and if
   the certification path cannot be validated on the basis of identified
   policies, then the certification path is considered invalid.

7  Algorithm Support

   This section describes cryptographic algorithms which may be used
   with this profile.  The section describes one-way hash functions and
   digital signature algorithms which may be used to sign certificates
   and CRLs, and identifies OIDs for public keys contained in a certifi-
   cate.

   Conforming CAs and applications are not required to support the algo-
   rithms or algorithm identifiers described in this section.  However,



Housley, Ford, Polk, & Solo                                    [Page 54]


INTERNET DRAFT                                             June 16, 1998


   conforming CAs and applications that use the algorithms identified
   here shall support them as specified.

7.1  One-way Hash Functions

   This section identifies one-way hash functions for use in the Inter-
   net PKI.  One-way hash functions are also called message digest algo-
   rithms. SHA-1 is the preferred one-way hash function for the Internet
   PKI.  However, PEM uses MD2 for certificates [RFC 1422] [RFC 1423]
   and MD5 is used in other legacy applications.  For this reason, MD2
   and MD5 are included in this profile.

7.1.1  MD2 One-way Hash Function

   MD2 was developed by Ron Rivest for RSA Data Security. RSA Data Secu-
   rity has not placed the MD2 algorithm in the public domain.  Rather,
   RSA Data Security has granted license to use MD2 for non-commercial
   Internet Privacy-Enhanced Mail.  For this reason, MD2 may continue to
   be used with PEM certificates, but SHA-1 is preferred.  MD2 produces
   a 128-bit "hash" of the input.  MD2 is fully described in RFC 1319
   [RFC 1319].

   At the Selected Areas in Cryptography '95 conference in May 1995,
   Rogier and Chauvaud presented an attack on MD2 that can nearly find
   collisions [RC95].  Collisions occur when one can find two different
   messages that generate the same message digest.  A checksum operation
   in MD2 is the only remaining obstacle to the success of the attack.
   For this reason, the use of MD2 for new applications is discouraged.
   It is still reasonable to use MD2 to verify existing signatures, as
   the ability to find collisions in MD2 does not enable an attacker to
   find new messages having a previously computed hash value.

7.1.2  MD5 One-way Hash Function

   MD5 was developed by Ron Rivest for RSA Data Security. RSA Data Secu-
   rity has placed the MD5 algorithm in the public domain.  MD5 produces
   a 128-bit "hash" of the input.  MD5 is fully described in RFC 1321
   [RFC 1321].

   Den Boer and Bosselaers [DB94] have found pseudo-collisions for MD5,
   but there are no other known cryptanalytic results.  The use of MD5
   for new applications is discouraged.  It is still reasonable to use
   MD5 to verify existing signatures.

7.1.3  SHA-1 One-way Hash Function

   SHA-1 was developed by the U.S. Government.  SHA-1 produces a 160-bit
   "hash" of the input. SHA-1 is fully described in FIPS 180-1 [FIPS



Housley, Ford, Polk, & Solo                                    [Page 55]


INTERNET DRAFT                                             June 16, 1998


   180-1].

   SHA-1 is the one-way hash function of choice for use with both the
   RSA and DSA signature algorithms (see sec. 7.2).

7.2  Signature Algorithms

   Certificates and CRLs described by this standard may be signed with
   any public key signature algorithm.  The certificate or CRL indicates
   the algorithm through an algorithm identifier which appears in the
   signatureAlgorithm field in a Certificate or CertificateList.  This
   algorithm identifier is an OID and has optionally associated parame-
   ters.  This section identifies algorithm identifiers and parameters
   that shall be used in the signatureAlgorithm field in a Certificate
   or CertificateList.

   RSA and DSA are the most popular signature algorithms used in the
   Internet.  Signature algorithms are always used in conjunction with a
   one-way hash function identified in section 7.1.

   The signature algorithm and one-way hash function used to sign a cer-
   tificate or CRL is indicated by use of an algorithm identifier.  An
   algorithm identifier is an OID, and may include associated parame-
   ters.  This section identifies OIDS for RSA and DSA.  The contents of
   the parameters component for each algorithm vary; details are pro-
   vided for each algorithm.

   The data to be signed (e.g., the one-way hash function output value)
   is formatted for the signature algorithm to be used.  Then, a private
   key operation (e.g., RSA encryption) is performed to generate the
   signature value.  This signature value is then ASN.1 encoded as a BIT
   STRING and included in the Certificate or CertificateList in the sig-
   nature field.

7.2.1  RSA Signature Algorithm

   A patent statement regarding the RSA algorithm can be found at the
   end of this profile.

   The RSA algorithm is named for its inventors: Rivest, Shamir, and
   Adleman.  This profile includes three signature algorithms based on
   the RSA asymmetric encryption algorithm. The signature algorithms
   combine RSA with either the MD2, MD5, or the SHA-1 one-way hash func-
   tions.

   The signature algorithm with MD2 and the RSA encryption algorithm is
   defined in PKCS #1 [RFC 2313].  As defined in RFC 2313, the ASN.1 OID
   used to identify this signature algorithm is:



Housley, Ford, Polk, & Solo                                    [Page 56]


INTERNET DRAFT                                             June 16, 1998


        md2WithRSAEncryption OBJECT IDENTIFIER  ::=  {
            iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
            pkcs-1(1) 2  }

   The signature algorithm with MD5 and the RSA encryption algorithm is
   defined in PKCS #1 [RFC 2313].  As defined in RFC 2313, the ASN.1 OID
   used to identify this signature algorithm is:

        md5WithRSAEncryption OBJECT IDENTIFIER  ::=  {
            iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
            pkcs-1(1) 4  }

   The signature algorithm with SHA-1 and the RSA encryption algorithm
   is implemented using the padding and encoding conventions described
   in PKCS #1 [RFC 2313]. The message digest is computed using the SHA-1
   hash algorithm.  The ASN.1 object identifier used to identify this
   signature algorithm is:

        sha-1WithRSAEncryption OBJECT IDENTIFIER  ::=  {
            iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
            pkcs-1(1) 5  }

   When any of these three OIDs appears within the ASN.1 type Algorith-
   mIdentifier, the parameters component of that type shall be the ASN.1
   type NULL.

   The RSA signature generation process and the encoding of the result
   is described in detail in RFC 2313.

7.2.2  DSA Signature Algorithm

   A patent statement regarding the DSA can be found at the end of this
   profile.

   The Digital Signature Algorithm (DSA) is also called the Digital Sig-
   nature Standard (DSS).  DSA was developed by the U.S. Government, and
   DSA is used in conjunction with the the SHA-1 one-way hash function.
   DSA is fully described in FIPS 186 [FIPS 186].  The ASN.1 OIDs used
   to identify this signature algorithm are:

           id-dsa-with-sha1 ID  ::=  {
                   iso(1) member-body(2) us(840) x9-57 (10040)
                   x9cm(4) 3 }

   Where the id-dsa-with-sha1 algorithm identifier appears as the algo-
   rithm field in an AlgorithmIdentifier, the encoding shall omit the
   parameters field.  That is, the AlgorithmIdentifier shall be a
   SEQUENCE of one component - the OBJECT IDENTIFIER id-dsa-with-sha1.



Housley, Ford, Polk, & Solo                                    [Page 57]


INTERNET DRAFT                                             June 16, 1998


   The DSA parameters in the subjectPublicKeyInfo field of the certifi-
   cate of the issuer shall apply to the verification of the signature.

   When signing, the DSA algorithm generates two values.  These values
   are commonly referred to as r and s.  To easily transfer these two
   values as one signature, they shall be ASN.1 encoded using the fol-
   lowing ASN.1 structure:

           Dss-Sig-Value  ::=  SEQUENCE  {
                   r       INTEGER,
                   s       INTEGER  }

7.3  Subject Public Key Algorithms

   Certificates described by this profile may convey a public key for
   any public key algorithm. The certificate indicates the algorithm
   through an algorithm identifier.  This algorithm identifier is an OID
   and optionally associated parameters.

   This section identifies preferred OIDs and parameters for the RSA,
   DSA, and Diffie-Hellman algorithms.  Conforming CAs shall use the
   identified OIDs when issuing certificates containing public keys for
   these algorithms. Conforming applications supporting any of these
   algorithms shall, at a minimum, recognize the OID identified in this
   section.

7.3.1  RSA Keys

   The OID rsaEncryption identifies RSA public keys.

        pkcs-1 OBJECT IDENTIFIER ::= { iso(1) member-body(2) us(840)
                       rsadsi(113549) pkcs(1) 1 }

        rsaEncryption OBJECT IDENTIFIER ::=  { pkcs-1 1}

   The rsaEncryption OID is intended to be used in the algorithm field
   of a value of type AlgorithmIdentifier. The parameters field shall
   have ASN.1 type NULL for this algorithm identifier.

   The RSA public key shall be encoded using the ASN.1 type RSAPub-
   licKey:

      RSAPublicKey ::= SEQUENCE {
         modulus            INTEGER, -- n
         publicExponent     INTEGER  -- e -- }

   where modulus is the modulus n, and publicExponent is the public
   exponent e.  The DER encoded RSAPublicKey is the value of the BIT



Housley, Ford, Polk, & Solo                                    [Page 58]


INTERNET DRAFT                                             June 16, 1998


   STRING subjectPublicKey.

   This OID is used in public key certificates for both RSA signature
   keys and RSA encryption keys. The intended application for the key
   may be indicated in the key usage field (see sec. 4.2.1.3).  The use
   of a single key for both signature and encryption purposes is not
   recommended, but is not forbidden.

   If the keyUsage extension is present in an end entity certificate
   which conveys an RSA public key, any combination of the following
   values may be present:  digitalSignature; nonRepudiation; keyEnci-
   pherment; and dataEncipherment.  If the keyUsage extension is present
   in a CA certificate which conveys an RSA public key, any combination
   of the following values may be present:  digitalSignature; nonRepudi-
   ation; keyEncipherment; dataEncipherment; keyCertSign; and cRLSign.
   However, this specification recommends that if keyCertSign or cRLSign
   is present, both keyEncipherment and dataEncipherment should not be
   present.

7.3.2  Diffie-Hellman Key Exchange Key

   The Diffie-Hellman OID supported by this profile is defined by ANSI
   X9.42 [X9.42].

        dhpublicnumber OBJECT IDENTIFIER ::= { iso(1) member-body(2)
                  us(840) ansi-x942(10046) number-type(2) 1 }

   The dhpublicnumber OID is intended to be used in the algorithm field
   of a value of type AlgorithmIdentifier. The parameters field of that
   type, which has the algorithm-specific syntax ANY DEFINED BY algo-
   rithm, have the ASN.1 type GroupParameters for this algorithm.

        DomainParameters ::= SEQUENCE {
              p       INTEGER, -- odd prime, p=jq +1
              g       INTEGER, -- generator, g
              q       INTEGER, -- factor of p-1
              j       INTEGER OPTIONAL, -- subgroup factor
              validationParms  ValidationParms OPTIONAL }

        ValidationParms ::= SEQUENCE {
              seed             BIT STRING,
              pgenCounter      INTEGER }

   The fields of type DomainParameters have the following meanings:

      p identifies the prime p defining the Galois field;

      g specifies the generator of the mutiplicative subgroup of order



Housley, Ford, Polk, & Solo                                    [Page 59]


INTERNET DRAFT                                             June 16, 1998


      g;

      q specifies the prime factor of p-1;

      j optionally specifies the value that satisfies the equation
      p=jq+1 to support the optional verification of group parameters;

      seed optionally specifies the bit string parameter used as the
      seed for the system parameter generation process; and

      pgenCounter optionally specifies the integer value output as part
      of the of the system parameter prime generation process.

   If either of the parameter generation components (pgencounter or
   seed) is provided, the other must be present as well.

   The Diffie-Hellman public key shall be ASN.1 encoded as an INTEGER;
   this encoding shall be used as the contents (i.e., the value) of the
   subjectPublicKey component (a BIT STRING) of the subjectPublicKeyInfo
   data element.

      DHPublicKey ::= INTEGER -- public key, y = g^x mod p

   If the keyUsage extension is present in a certificate which conveys a
   DH public key, the following values may be present:  keyAgreement;
   encipherOnly; and decipherOnly.  At most one of encipherOnly and
   decipherOnly shall be asserted in keyUsage extension.

7.3.3  DSA Signature Keys

   The Digital Signature Algorithm (DSA) is also known as the Digitial
   Signature Standard (DSS). The DSA OID supported by this profile is

        id-dsa ID ::= { iso(1) member-body(2) us(840) x9-57(10040)
                  x9cm(4) 1 }

   The id-dsa algorithm syntax includes optional parameters.  These
   parameters are commonly referred to as p, q, and g.  When omitted,
   the parameters component shall be omitted entirely. That is, the
   AlgorithmIdentifier shall be a SEQUENCE of one component - the OBJECT
   IDENTIFIER id-dsa.

   If the DSA algorithm parameters are present in the subjectPublicKey-
   Info AlgorithmIdentifier, the parameters are included using the fol-
   lowing ASN.1 structure:

        Dss-Parms  ::=  SEQUENCE  {
            p             INTEGER,



Housley, Ford, Polk, & Solo                                    [Page 60]


INTERNET DRAFT                                             June 16, 1998


            q             INTEGER,
            g             INTEGER  }


   If the DSA algorithm parameters are absent from the subjectPublicKey-
   Info AlgorithmIdentifier and the CA signed the subject certificate
   using DSA, then the certificate issuer's DSA parameters apply to the
   subject's DSA key.  If the DSA algorithm parameters are absent from
   the subjectPublicKeyInfo AlgorithmIdentifier and the CA signed the
   subject certificate using a signature algorithm other than DSA, then
   the subject's DSA parameters are distributed by other means.  If the
   subjectPublicKeyInfo AlgorithmIdentifier field omits the parameters
   component and the CA signed the subject with a signature algorithm
   other than DSA, then clients shall reject the certificate.

   When signing, DSA algorithm generates two values.  These values are
   commonly referred to as r and s.  To easily transfer these two values
   as one signature, they are ASN.1 encoded using the following ASN.1
   structure:

        Dss-Sig-Value  ::=  SEQUENCE  {
            r             INTEGER,
            s             INTEGER  }

   The encoded signature is conveyed as the value of the BIT STRING sig-
   nature in a Certificate or CertificateList.

   The DSA public key shall be ASN.1 DER encoded as an INTEGER; this
   encoding shall be used as the contents (i.e., the value) of the sub-
   jectPublicKey component (a BIT STRING) of the SubjectPublicKeyInfo
   data element.

        DSAPublicKey ::= INTEGER -- public key, Y


   If the keyUsage extension is present in an end entity certificate
   which conveys a DSA public key, any combination of the following
   values may be present:  digitalSignature; and nonRepudiation.

   If the keyUsage extension is present in an CA certificate which con-
   veys a DSA public key, any combination of the following values may be
   present:  digitalSignature; nonRepudiation; keyCertSign; and cRLSign.

8 References

   [FIPS 180-1]  Federal Information Processing Standards Publication
            (FIPS PUB) 180-1, Secure Hash Standard, 17 April 1995.
            [Supersedes FIPS PUB 180 dated 11 May 1993.]



Housley, Ford, Polk, & Solo                                    [Page 61]


INTERNET DRAFT                                             June 16, 1998


   [FIPS 186] Federal Information Processing Standards Publication
            (FIPS PUB) 186, Digital Signature Standard, 18 May 1994.

   [PKCS #9] PKCS #9: Selected Attribute Types, Version 1.1, RSA Data
            Security, Inc., November 1, 1993.

   [RC95]   Rogier, N. and Chauvaud, P., "The compression function of
            MD2 is not collision free," Presented at Selected Areas in
            Cryptography '95, May 1995.

   [RFC 791] J. Postel, "Internet Protocol", September 1981.

   [RFC 822] D. Crocker, "Standard for the format of ARPA Internet text
            messages", August 1982.

   [RFC 1034] P.V. Mockapetris, "Domain names - concepts and facili-
   ties",
            November 1987.

   [RFC 1319] Kaliski, B., "The MD2 Message-Digest Algorithm," RFC 1319,
            RSA Laboratories, April 1992.

   [RFC 1422] Kent, S.,  "Privacy Enhancement for Internet Electronic
            Mail: Part II: Certificate-Based Key Management," RFC
            1422, BBN Communications, February 1993.

   [RFC 1423] Balenson, D., "Privacy Enhancement for Internet Electronic
            Mail: Part III: Algorithms, Modes, and Identifiers,"
            RFC 1423, Trusted Information Systems, February 1993.

   [RFC 1519] V. Fuller, T. Li, J. Yu, and K. Varadhan. "Classless
            Inter-Domain Routing (CIDR): an Address Assignment and
            Aggregation Strategy", September 1993.

   [RFC 1883] S. Deering and R. Hinden. "Internet Protocol, Version 6
            (IPv6) Specification", December 1995.

   [RFC 2044] F. Yergeau, "UTF-8, a transformation format of Unicode
            and ISO 10646", October 1996.

   [RFC 2119] S. Bradner, "Key words for use in RFCs to Indicate
            Requirement Levels", March 1997.

   [RFC 2277] H. Alvestrand, "IETF Policy on Character Sets and
            Languages", January 1998.

   [RFC 2279] F. Yergeau, "UTF-8, a transformation format of ISO 10646",
            January 1998.



Housley, Ford, Polk, & Solo                                    [Page 62]


INTERNET DRAFT                                             June 16, 1998


   [RFC 2313] B. Kaliski, "PKCS #1: RSA Encryption Version 1.5",
            March 1998.

   [SDN.701] SDN.701, "Message Security Protocol 4.0", Revision A
            1997-02-06.

   [X.208]  CCITT Recommendation X.208: Specification of Abstract
              Syntax Notation One (ASN.1), 1988.

   [X.509]  ITU-T Recommendation X.509 (1997 E): Information
            Technology - Open Systems Interconnection - The
            Directory: Authentication Framework, June 1997.

   [X9.42]  ANSI X9.42-199x, Public Key Cryptography for The Financial
            Services Industry: Agreement of Symmetric Algorithm Keys
            Using Diffie-Hellman (Working Draft), December 1997.

   [X9.55]  ANSI X9.55-1995, Public Key Cryptography For The Financial
            Services Industry: Extensions To Public Key Certificates
            And Certificate Revocation Lists, 8 December, 1995.

   [X9.57]  ANSI X9.57-199x, Public Key Cryptography For The Financial
            Services Industry: Certificate Management (Working Draft),
            21 June, 1996.

9  Patent Statements

   The Internet PKI relies on the use of patented public key technology
   and secure hash technology for digital signature services.  This
   specification references public key encryption technology for provi-
   sioning key exchange services.

   The Internet Standards Process as defined in RFC 1310 requires a
   written statement from the Patent holder that a license will be made
   available to applicants under reasonable terms and conditions prior
   to approving a specification as a Proposed, Draft or Internet Stan-
   dard.

   Patent statements for DSA, RSA, Diffie-Hellman, and Hellman-Merkle
   follow.  These statements have been supplied by the patent holders,
   not the authors of this profile.

   The Internet Society, Internet Architecture Board, Internet Engineer-
   ing Steering Group and the Corporation for National Research Initia-
   tives take no position on the validity or scope of the following
   patents and patent applications, nor on the appropriateness of the
   terms of the assurance. The Internet Society and other groups men-
   tioned above have not made any determination as to any other



Housley, Ford, Polk, & Solo                                    [Page 63]


INTERNET DRAFT                                             June 16, 1998


   intellectual property rights which may apply to the practice of this
   standard.  Any further consideration of these matters is the user's
   responsibility.

9.1  Digital Signature Algorithm (DSA)

   The U.S. Government holds patent 5,231,668 on the Digital Signature
   Algorithm (DSA), which has been incorporated into Federal Information
   Processing Standard (FIPS) 186.  The patent was issued on July 27,
   1993.

   The National Institute of Standards and Technology (NIST) has a long
   tradition of supplying U.S. Government-developed techniques to com-
   mittees and working groups for inclusion into standards on a
   royalty-free basis.  NIST has made the DSA patent available royalty-
   free to users worldwide.

   NIST has provided the following statement with regard to this patent:

      Regarding patent infringement, FIPS 186 summarizes our position;
      the Department of Commerce is not aware of any patents that would
      be infringed by the DSA.  Questions regarding this matter may be
      directed to the Deputy Chief Counsel for NIST.

9.2  RSA Signature and Encryption

   The Massachusetts Institute of Technology has granted RSA Data Secu-
   rity, Inc., exclusive sub-licensing rights to the following patent
   issued in the United States:

   Cryptographic Communications System and Method ("RSA"), No. 4,405,829

   RSA Data Security, Inc. has provided the following statement with
   regard to this patent:

      It is our understanding that the proposed PKIX Certificate Profile
      (PKIX-1) standard currently under review contemplates the use of
      U.S Patent 4,405,829 entitled "Cryptographic Communication System
      and Method" (the "RSA patent") which patent is controlled by RSA.

      It is RSA's business practice to make licenses to its patents
      available on reasonable and nondiscriminatory terms. Accordingly,
      if the foregoing identified IETF standard is adopted, RSA is wil-
      ling, upon request, to grant non-exclusive licenses to such patent
      on reasonable and non-discriminatory terms and conditions to those
      who respect RSA's intellectual property rights and subject to
      RSA's then current royalty rate for the patent licensed. The roy-
      alty rate for the RSA patent is presently set at 2% of the



Housley, Ford, Polk, & Solo                                    [Page 64]


INTERNET DRAFT                                             June 16, 1998


      licensee's selling price for each product covered by the patent.
      Any requests for license information may be directed to:

         Director of Licensing
         RSA Data Security, Inc.
         100 Marine Parkway, Suite 500
         Redwood City, CA 94065

      A license under RSA's patent(s) does not include any rights to
      know-how or other technical information or license under other
      intellectual property rights.  Such license does not extend to any
      activities which constitute infringement or inducement thereto. A
      licensee must make his own determination as to whether a license
      is necessary under patents of others.

9.3  Diffie-Hellman Key Agreement

   Patent No. 4,200,770: Cryptographic Apparatus and Method ("Diffie-
   Hellman") expired on August 19, 1997.

9.4  Hellman-Merkle Public Key Cryptography

   Patent No. 4,218,582: Public Key Cryptographic Apparatus and Method
   ("Hellman-Merkle") expired on April 29, 1997.

9.5  CRL Distribution Points and Related Mechanisms

   Entrust Technologies Incorporated has provided the following state-
   ment with regard to this patent:

      Entrust Technologies Incorporated advises the IETF that it holds
      the Patent (as defined herein) which may relate to the IETF. In
      accordance with the Intellectual Property rights procedures of the
      IETF standards process, Entrust Technologies Incorporated, for
      itself and its subsidiaries (hereinafter called "Entrust") will
      offer licenses under its Patent on a perpetual, royalty-free,
      non-exclusive basis and on non-discriminatory, fair and equitable
      terms to all parties solely for their use in complying with the
      Standard, but on condition that any such party offers to Entrust
      and its corporate affiliates similar licenses under such party's
      patents, if any, for use in complying with the Standard.

      Any application for a license under Entrust's Patent pursuant to
      this Patent Disclosure Statement should be made to:

         Stephen Samson
         Entrust Technologies Limited
         750 Heron Road, Ottawa, Ontario, Canada, K1V 1A7



Housley, Ford, Polk, & Solo                                    [Page 65]


INTERNET DRAFT                                             June 16, 1998


         voice: (613) 247 3725

      As used herein:

      "Patent" means US Patent 5,699,431 issued on 16 December, 1997 for
      an invention known as a "Method for Efficient Management of Certi-
      ficate Revocation Lists and Update Information", which invention
      is owned or controlled by Entrust and the use of which may be
      required in conjunction with the Standard.

      "Standard" means a specification progressing through the Standard
      Track of the IETF and relating to the Public Key Infrastructure
      (X.509) specification for certificate update and revocation.

10  Security Considerations

   The majority of this specification is devoted to the format and con-
   tent of certificates and CRLs.  Since certificates and CRLs are digi-
   tally signed, no additional integrity service is necessary. Neither
   certificates nor CRLs need be kept secret, and unrestricted and
   anonymous access to certificates and CRLs has no security implica-
   tions.

   However, security factors outside the scope of this specification
   will affect the assurance provided to certificate users.  This sec-
   tion highlights critical issues that should be considered by imple-
   mentors, administrators, and users.

   The procedures performed by CAs and RAs to validate the binding of
   the subject's identity of their public key greatly affect the
   assurance that should be placed in the certificate.  Relying parties
   may wish to review the CA's certificate practice statement.  This may
   be particularly important when issuing certificates to other CAs.

   The use of a single key pair for both signature and other purposes is
   strongly discouraged. Use of separate key pairs for signature and key
   management provides several benefits to the users. The ramifications
   associated with loss or disclosure of a signature key are different
   from loss or disclosure of a key management key. Using separate key
   pairs permits a balanced and flexible response.  Similarly, different
   validity periods or key lengths for each key pair may be appropriate
   in some application environments. Unfortunately, some legacy applica-
   tions (e.g., SSL) use a single key pair for signature and key manage-
   ment.

   The protection afforded private keys is a critical factor in main-
   taining security.  On a small scale, failure of users to protect
   their private keys will permit an attacker to masquerade as them, or



Housley, Ford, Polk, & Solo                                    [Page 66]


INTERNET DRAFT                                             June 16, 1998


   decrypt their personal information. On a larger scale, compromise of
   a CA's private signing key may have a catastrophic effect.  If an
   attacker obtains the private key unnoticed, the attacker may issue
   bogus certificates and CRLs.  Existence of bogus certificates and
   CRLs will undermine confidence in the system. If the compromise is
   detected, all certificates issued to the CA must be revoked, prevent-
   ing services between its users and users of other CAs. Rebuilding
   after such a compromise will be problematic, so CAs are advised to
   implement a combination of strong technical measures (e.g., tamper-
   resistant cryptographic modules) and appropriate management pro-
   cedures (e.g., separation of duties) to avoid such an incident.

   Loss of a CA's private signing key may also be problematic.  The CA
   would not be able to produce CRLs or perform normal key rollover.
   CAs are advised to maintain secure backup for signing keys.  The
   security of the key backup procedures is a critical factor in avoid-
   ing key compromise.

   The availability and freshness of revocation information will affect
   the degree of assurance that should be placed in a certificate.
   While certificates expire naturally, events may occur during its
   natural lifetime which negate the binding between the subject and
   public key.  If revocation information is untimely or unavailable,
   the assurance associated with the binding is clearly reduced.  Simi-
   larly, implementations of the Path Validation mechanism described in
   section 6 that omit revocation checking provide less assurance than
   those that support it.

   The path validation algorithm depends on the certain knowledge of the
   public keys (and other information) about one or more trusted CAs.
   The decision to trust a CA is an important decision as it ultimately
   determines the trust afforded a certificate. The authenticated dis-
   tribution of trusted CA public keys (usually in the form of a "self-
   signed" certificate) is a security critical out of band process that
   is beyond the scope of this specification.

   In addition, where a key compromise or CA failure occurs for a
   trusted CA, the user will need to modify the information provided to
   the path validation routine.  Selection of too many trusted CAs will
   make the trusted CA information difficult to maintain.  On the other
   hand, selection of only one trusted CA may limit users to a closed
   community of users until a global PKI emerges.

   The quality of implementations that process certificates may also
   affect the degree of assurance provided.  The path validation algo-
   rithm described in section 6 relies upon the integrity of the trusted
   CA information, and especially the integrity of the public keys asso-
   ciated with the trusted CAs.  By substituting public keys for which



Housley, Ford, Polk, & Solo                                    [Page 67]


INTERNET DRAFT                                             June 16, 1998


   an attacker has the private key, an attacker could trick the user
   into accepting false certificates.

   Finally, the binding between a key and certificate subject cannot be
   stronger than the cryptographic module implementation and algorithms
   used to generate the signature.  Short key lengths or weak hash algo-
   rithms will limit the utility of a certificate.  CAs are encouraged
   to note advances in cryptology so they can employ strong crypto-
   graphic techniques.  In addition, CAs should decline to issue certi-
   ficates to CAs or end entities that generate weak signatures.









































Housley, Ford, Polk, & Solo                                    [Page 68]


INTERNET DRAFT                                             June 16, 1998


Appendix A. Psuedo-ASN.1 Structures and OIDs

   This section describes data objects used by conforming PKI components
   in an "ASN.1-like" syntax.  This syntax is a hybrid of the 1988 and
   1993 ASN.1 syntaxes.  The 1988 ASN.1 syntax is augmented with 1993
   UNIVERSAL Types UniversalString, BMPString and UTF8String.

   The ASN.1 syntax does not permit the inclusion of type statements in
   the ASN.1 module, and the 1993 ASN.1 standard does not permit use of
   the new UNIVERSAL types in modules using the 1988 syntax.  As a
   result, this module does not conform to either version of the ASN.1
   standard.

   This appendix may be converted into 1988 ASN.1 by replacing the
   defintions for the UNIVERSAL Types with the 1988 catch-all "ANY".

A.1 Explicitly Tagged Module

PKIX1Explicit88 {iso(1) identified-organization(3) dod(6) internet(1)
  security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-explicit-88(1)}


DEFINITIONS EXPLICIT TAGS ::=

BEGIN

-- EXPORTS ALL --

-- IMPORTS NONE --

-- UNIVERSAL Types defined in '93 and '98 ASN.1
-- but required by this specification

UniversalString ::= [UNIVERSAL 28] IMPLICIT OCTET STRING
        -- UniversalString is defined in ASN.1:1993

BMPString ::= [UNIVERSAL 30] IMPLICIT OCTET STRING
      -- BMPString is the subtype of UniversalString and models
        -- the Basic Multilingual Plane of ISO/IEC/ITU 10646-1

UTF8String ::= [UNIVERSAL 12] IMPLICIT OCTET STRING
        -- The content of this type conforms to RFC 2044.

--
-- PKIX specific OIDs

id-pkix  OBJECT IDENTIFIER  ::=
         { iso(1) identified-organization(3) dod(6) internet(1)



Housley, Ford, Polk, & Solo                                    [Page 69]


INTERNET DRAFT                                             June 16, 1998


                    security(5) mechanisms(5) pkix(7) }
-- PKIX arcs

id-pe OBJECT IDENTIFIER  ::=  { id-pkix 1 }
        -- arc for private certificate extensions
id-qt OBJECT IDENTIFIER ::= { id-pkix 2 }
        -- arc for policy qualifier types
id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }
        -- arc for extended key purpose OIDS
id-ad OBJECT IDENTIFIER ::= { id-pkix 48 }
        -- arc for access descriptors

-- policyQualifierIds for Internet policy qualifiers

id-qt-cps      OBJECT IDENTIFIER ::=  { id-qt 1 }
        -- OID for CPS qualifier
id-qt-unotice  OBJECT IDENTIFIER ::=  { id-qt 2 }
        -- OID for user notice qualifier

-- attribute data types --

Attribute       ::=     SEQUENCE {
        type            AttributeType,
        values  SET OF AttributeValue
                -- at least one value is required -- }

AttributeType           ::=   OBJECT IDENTIFIER

AttributeValue          ::=   ANY

AttributeTypeAndValue           ::=     SEQUENCE {
        type    AttributeType,
        value   AttributeValue }

-- suggested naming attributes: Definition of the following
--  information object set may be augmented to meet local
--  requirements.  Note that deleting members of the set may
--  prevent interoperability with conforming implementations.
--  presented in pairs: the AttributeType followed by the
--  type definition for the corresponding AttributeValue

--Arc for standard naming attributes
id-at           OBJECT IDENTIFIER ::= {joint-iso-ccitt(2) ds(5) 4}

-- Attributes of type NameDirectoryString
id-at-name              AttributeType   ::=     {id-at 41}
id-at-surname           AttributeType   ::=     {id-at 4}
id-at-givenName         AttributeType   ::=     {id-at 42}



Housley, Ford, Polk, & Solo                                    [Page 70]


INTERNET DRAFT                                             June 16, 1998


id-at-initials          AttributeType   ::=     {id-at 43}
id-at-generationQualifier       AttributeType   ::=     {id-at 44}

X520name        ::= CHOICE {
      teletexString         TeletexString (SIZE (1..ub-name)),
      printableString       PrintableString (SIZE (1..ub-name)),
      universalString       UniversalString (SIZE (1..ub-name)),
      utf8String            UTF8String (SIZE (1..ub-name)),
      bmpString             BMPString (SIZE(1..ub-name))   }

--

id-at-commonName        AttributeType   ::=     {id-at 3}

X520CommonName  ::=      CHOICE {
      teletexString         TeletexString (SIZE (1..ub-common-name)),
      printableString       PrintableString (SIZE (1..ub-common-name)),
      universalString       UniversalString (SIZE (1..ub-common-name)),
      utf8String            UTF8String (SIZE (1..ub-common-name)),
      bmpString             BMPString (SIZE(1..ub-common-name))   }

--

id-at-localityName      AttributeType   ::=     {id-at 7}

X520LocalityName ::= CHOICE {
      teletexString       TeletexString (SIZE (1..ub-locality-name)),
      printableString     PrintableString (SIZE (1..ub-locality-name)),
      universalString     UniversalString (SIZE (1..ub-locality-name)),
      utf8String          UTF8String (SIZE (1..ub-locality-name)),
      bmpString           BMPString (SIZE(1..ub-locality-name))   }

--

id-at-stateOrProvinceName       AttributeType   ::=     {id-at 8}

X520StateOrProvinceName         ::= CHOICE {
      teletexString       TeletexString (SIZE (1..ub-state-name)),
      printableString     PrintableString (SIZE (1..ub-state-name)),
      universalString     UniversalString (SIZE (1..ub-state-name)),
      utf8String          UTF8String (SIZE (1..ub-state-name)),
      bmpString             BMPString (SIZE(1..ub-state-name))   }

--

id-at-organizationName          AttributeType   ::=     {id-at 10}

X520OrganizationName ::= CHOICE {



Housley, Ford, Polk, & Solo                                    [Page 71]


INTERNET DRAFT                                             June 16, 1998


  teletexString    TeletexString (SIZE (1..ub-organization-name)),
  printableString  PrintableString (SIZE (1..ub-organization-name)),
  universalString  UniversalString (SIZE (1..ub-organization-name)),
  utf8String       UTF8String (SIZE (1..ub-organization-name)),
  bmpString        BMPString (SIZE(1..ub-organization-name))   }

--

id-at-organizationalUnitName    AttributeType   ::=     {id-at 11}

X520OrganizationalUnitName ::= CHOICE {
 teletexString   TeletexString (SIZE (1..ub-organizational-unit-name)),
 printableString PrintableString
                      (SIZE (1..ub-organizational-unit-name)),
 universalString UniversalString
                      (SIZE (1..ub-organizational-unit-name)),
 utf8String      UTF8String (SIZE (1..ub-organizational-unit-name)),
 bmpString       BMPString (SIZE(1..ub-organizational-unit-name))   }

--

id-at-title     AttributeType   ::=     {id-at 12}

X520Title ::=   CHOICE {
      teletexString         TeletexString (SIZE (1..ub-title)),
      printableString       PrintableString (SIZE (1..ub-title)),
      universalString       UniversalString (SIZE (1..ub-title)),
      utf8String            UTF8String (SIZE (1..ub-title)),
      bmpString             BMPString (SIZE(1..ub-title))   }

--

id-at-dnQualifier       AttributeType   ::=     {id-at 46}
X520dnQualifier ::=     PrintableString

id-at-countryName       AttributeType   ::=     {id-at 6}
X520countryName ::=     PrintableString (SIZE (2)) -- IS 3166 codes


 -- Legacy attributes

pkcs-9 OBJECT IDENTIFIER ::=
       { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 9 }

emailAddress AttributeType      ::= { pkcs-9 1 }

Pkcs9email ::= IA5String (SIZE (1..ub-emailaddress-length))




Housley, Ford, Polk, & Solo                                    [Page 72]


INTERNET DRAFT                                             June 16, 1998


-- naming data types --

Name            ::=   CHOICE { -- only one possibility for now --
                                 rdnSequence  RDNSequence }

RDNSequence     ::=   SEQUENCE OF RelativeDistinguishedName

DistinguishedName       ::=   RDNSequence

RelativeDistinguishedName  ::=
                    SET SIZE (1 .. MAX) OF AttributeTypeAndValue

-- Directory string type --

DirectoryString ::= CHOICE {
      teletexString             TeletexString (SIZE (1..MAX)),
      printableString           PrintableString (SIZE (1..MAX)),
      universalString           UniversalString (SIZE (1..MAX)),
      utf8String              UTF8String (SIZE (1..MAX)),
      bmpString               BMPString (SIZE(1..MAX))   }

-- certificate and CRL specific structures begin here

Certificate  ::=  SEQUENCE  {
     tbsCertificate       TBSCertificate,
     signatureAlgorithm   AlgorithmIdentifier,
     signature            BIT STRING  }

TBSCertificate  ::=  SEQUENCE  {
     version         [0]  Version DEFAULT v1,
     serialNumber         CertificateSerialNumber,
     signature            AlgorithmIdentifier,
     issuer               Name,
     validity             Validity,
     subject              Name,
     subjectPublicKeyInfo SubjectPublicKeyInfo,
     issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,
                          -- If present, version must be v2 or v3
     subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,
                          -- If present, version must be v2 or v3
     extensions      [3]  Extensions OPTIONAL
                          -- If present, version must be v3 --  }

Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }

CertificateSerialNumber  ::=  INTEGER

Validity ::= SEQUENCE {



Housley, Ford, Polk, & Solo                                    [Page 73]


INTERNET DRAFT                                             June 16, 1998


     notBefore      Time,
     notAfter       Time }

Time ::= CHOICE {
     utcTime        UTCTime,
     generalTime    GeneralizedTime }

UniqueIdentifier  ::=  BIT STRING

SubjectPublicKeyInfo  ::=  SEQUENCE  {
     algorithm            AlgorithmIdentifier,
     subjectPublicKey     BIT STRING  }

Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension

Extension  ::=  SEQUENCE  {
     extnID      OBJECT IDENTIFIER,
     critical    BOOLEAN DEFAULT FALSE,
     extnValue   OCTET STRING  }

-- CRL structures

CertificateList  ::=  SEQUENCE  {
     tbsCertList          TBSCertList,
     signatureAlgorithm   AlgorithmIdentifier,
     signature            BIT STRING  }

TBSCertList  ::=  SEQUENCE  {
     version                 Version OPTIONAL,
                                  -- if present, must be v2
     signature               AlgorithmIdentifier,
     issuer                  Name,
     thisUpdate              Time,
     nextUpdate              Time OPTIONAL,
     revokedCertificates     SEQUENCE OF SEQUENCE  {
          userCertificate         CertificateSerialNumber,
          revocationDate          Time,
          crlEntryExtensions      Extensions OPTIONAL
                                         -- if present, must be v2
                               }  OPTIONAL,
     crlExtensions           [0] Extensions OPTIONAL
                                         -- if present, must be v2 -- }

-- Version, Time, CertificateSerialNumber, and Extensions were
-- defined earlier for use in the certificate structure

AlgorithmIdentifier  ::=  SEQUENCE  {
     algorithm               OBJECT IDENTIFIER,



Housley, Ford, Polk, & Solo                                    [Page 74]


INTERNET DRAFT                                             June 16, 1998


     parameters              ANY DEFINED BY algorithm OPTIONAL  }
                                -- contains a value of the type
                                -- registered for use with the
                                -- algorithm object identifier value

-- Algorithm OIDs and parameter structures

pkcs-1 OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 }

rsaEncryption OBJECT IDENTIFIER ::=  { pkcs-1 1 }

md2WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 2 }

md5WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 4 }

sha1WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 5 }

id-dsa-with-sha1 OBJECT IDENTIFIER ::=  {
     iso(1) member-body(2) us(840) x9-57 (10040) x9algorithm(4) 3 }

Dss-Sig-Value  ::=  SEQUENCE  {
     r       INTEGER,
     s       INTEGER  }

dhpublicnumber OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-x942(10046) number-type(2) 1 }

DomainParameters ::= SEQUENCE {
     p       INTEGER, -- odd prime, p=jq +1
     g       INTEGER, -- generator, g
     q       INTEGER, -- factor of p-1
     j       INTEGER OPTIONAL, -- subgroup factor, j>= 2
     validationParms  ValidationParms OPTIONAL }

ValidationParms ::= SEQUENCE {
     seed             BIT STRING,
     pgenCounter      INTEGER }

id-dsa OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) x9-57(10040) x9algorithm(4) 1 }

Dss-Parms  ::=  SEQUENCE  {
     p             INTEGER,
     q             INTEGER,
     g             INTEGER  }

-- x400 address syntax starts here



Housley, Ford, Polk, & Solo                                    [Page 75]


INTERNET DRAFT                                             June 16, 1998


--      OR Names

ORAddress ::= SEQUENCE {
   built-in-standard-attributes BuiltInStandardAttributes,
   built-in-domain-defined-attributes
                        BuiltInDomainDefinedAttributes OPTIONAL,
   -- see also teletex-domain-defined-attributes
   extension-attributes ExtensionAttributes OPTIONAL }
--      The OR-address is semantically absent from the OR-name if the
--      built-in-standard-attribute sequence is empty and the
--      built-in-domain-defined-attributes and extension-attributes are
--      both omitted.

--      Built-in Standard Attributes

BuiltInStandardAttributes ::= SEQUENCE {
   country-name CountryName OPTIONAL,
   administration-domain-name AdministrationDomainName OPTIONAL,
   network-address      [0] NetworkAddress OPTIONAL,
   -- see also extended-network-address
   terminal-identifier  [1] TerminalIdentifier OPTIONAL,
   private-domain-name  [2] PrivateDomainName OPTIONAL,
   organization-name    [3] OrganizationName OPTIONAL,
   -- see also teletex-organization-name
   numeric-user-identifier      [4] NumericUserIdentifier OPTIONAL,
   personal-name        [5] PersonalName OPTIONAL,
   -- see also teletex-personal-name
   organizational-unit-names    [6] OrganizationalUnitNames OPTIONAL
   -- see also teletex-organizational-unit-names -- }

CountryName ::= [APPLICATION 1] CHOICE {
   x121-dcc-code NumericString
                (SIZE (ub-country-name-numeric-length)),
   iso-3166-alpha2-code PrintableString
                (SIZE (ub-country-name-alpha-length)) }

AdministrationDomainName ::= [APPLICATION 2] CHOICE {
   numeric NumericString (SIZE (0..ub-domain-name-length)),
   printable PrintableString (SIZE (0..ub-domain-name-length)) }

NetworkAddress ::= X121Address  -- see also extended-network-address

X121Address ::= NumericString (SIZE (1..ub-x121-address-length))

TerminalIdentifier ::= PrintableString (SIZE (1..ub-terminal-id-length))

PrivateDomainName ::= CHOICE {
   numeric NumericString (SIZE (1..ub-domain-name-length)),



Housley, Ford, Polk, & Solo                                    [Page 76]


INTERNET DRAFT                                             June 16, 1998


   printable PrintableString (SIZE (1..ub-domain-name-length)) }

OrganizationName ::= PrintableString
                            (SIZE (1..ub-organization-name-length))
-- see also teletex-organization-name

NumericUserIdentifier ::= NumericString
                            (SIZE (1..ub-numeric-user-id-length))

PersonalName ::= SET {
   surname [0] PrintableString (SIZE (1..ub-surname-length)),
   given-name [1] PrintableString
                        (SIZE (1..ub-given-name-length)) OPTIONAL,
   initials [2] PrintableString (SIZE (1..ub-initials-length)) OPTIONAL,
   generation-qualifier [3] PrintableString
                (SIZE (1..ub-generation-qualifier-length)) OPTIONAL }
-- see also teletex-personal-name

OrganizationalUnitNames ::= SEQUENCE SIZE (1..ub-organizational-units)
                                        OF OrganizationalUnitName
-- see also teletex-organizational-unit-names

OrganizationalUnitName ::= PrintableString (SIZE
                        (1..ub-organizational-unit-name-length))

--      Built-in Domain-defined Attributes

BuiltInDomainDefinedAttributes ::= SEQUENCE SIZE
                                (1..ub-domain-defined-attributes) OF
                                BuiltInDomainDefinedAttribute

BuiltInDomainDefinedAttribute ::= SEQUENCE {
   type PrintableString (SIZE
                        (1..ub-domain-defined-attribute-type-length)),
   value PrintableString (SIZE
                        (1..ub-domain-defined-attribute-value-length))}

--      Extension Attributes

ExtensionAttributes ::= SET SIZE (1..ub-extension-attributes) OF
                        ExtensionAttribute

ExtensionAttribute ::=  SEQUENCE {
   extension-attribute-type [0] INTEGER (0..ub-extension-attributes),
   extension-attribute-value [1]
                        ANY DEFINED BY extension-attribute-type }

-- Extension types and attribute values



Housley, Ford, Polk, & Solo                                    [Page 77]


INTERNET DRAFT                                             June 16, 1998


--

common-name INTEGER ::= 1

CommonName ::= PrintableString (SIZE (1..ub-common-name-length))

teletex-common-name INTEGER ::= 2

TeletexCommonName ::= TeletexString (SIZE (1..ub-common-name-length))

teletex-organization-name INTEGER ::= 3

TeletexOrganizationName ::=
                TeletexString (SIZE (1..ub-organization-name-length))

teletex-personal-name INTEGER ::= 4

TeletexPersonalName ::= SET {
   surname [0] TeletexString (SIZE (1..ub-surname-length)),
   given-name [1] TeletexString
                (SIZE (1..ub-given-name-length)) OPTIONAL,
   initials [2] TeletexString (SIZE (1..ub-initials-length)) OPTIONAL,
   generation-qualifier [3] TeletexString (SIZE
                (1..ub-generation-qualifier-length)) OPTIONAL }

teletex-organizational-unit-names INTEGER ::= 5

TeletexOrganizationalUnitNames ::= SEQUENCE SIZE
        (1..ub-organizational-units) OF TeletexOrganizationalUnitName

TeletexOrganizationalUnitName ::= TeletexString
                        (SIZE (1..ub-organizational-unit-name-length))

pds-name INTEGER ::= 7

PDSName ::= PrintableString (SIZE (1..ub-pds-name-length))

physical-delivery-country-name INTEGER ::= 8

PhysicalDeliveryCountryName ::= CHOICE {
   x121-dcc-code NumericString (SIZE (ub-country-name-numeric-length)),
   iso-3166-alpha2-code PrintableString
                        (SIZE (ub-country-name-alpha-length)) }

postal-code INTEGER ::= 9

PostalCode ::= CHOICE {
   numeric-code NumericString (SIZE (1..ub-postal-code-length)),



Housley, Ford, Polk, & Solo                                    [Page 78]


INTERNET DRAFT                                             June 16, 1998


   printable-code PrintableString (SIZE (1..ub-postal-code-length)) }

physical-delivery-office-name INTEGER ::= 10

PhysicalDeliveryOfficeName ::= PDSParameter

physical-delivery-office-number INTEGER ::= 11

PhysicalDeliveryOfficeNumber ::= PDSParameter

extension-OR-address-components INTEGER ::= 12

ExtensionORAddressComponents ::= PDSParameter

physical-delivery-personal-name INTEGER ::= 13

PhysicalDeliveryPersonalName ::= PDSParameter

physical-delivery-organization-name INTEGER ::= 14

PhysicalDeliveryOrganizationName ::= PDSParameter

extension-physical-delivery-address-components INTEGER ::= 15

ExtensionPhysicalDeliveryAddressComponents ::= PDSParameter

unformatted-postal-address INTEGER ::= 16

UnformattedPostalAddress ::= SET {
   printable-address SEQUENCE SIZE (1..ub-pds-physical-address-lines) OF
           PrintableString (SIZE (1..ub-pds-parameter-length)) OPTIONAL,
   teletex-string TeletexString
         (SIZE (1..ub-unformatted-address-length)) OPTIONAL }

street-address INTEGER ::= 17

StreetAddress ::= PDSParameter

post-office-box-address INTEGER ::= 18

PostOfficeBoxAddress ::= PDSParameter

poste-restante-address INTEGER ::= 19

PosteRestanteAddress ::= PDSParameter

unique-postal-name INTEGER ::= 20




Housley, Ford, Polk, & Solo                                    [Page 79]


INTERNET DRAFT                                             June 16, 1998


UniquePostalName ::= PDSParameter

local-postal-attributes INTEGER ::= 21

LocalPostalAttributes ::= PDSParameter

PDSParameter ::= SET {
   printable-string PrintableString
                (SIZE(1..ub-pds-parameter-length)) OPTIONAL,
   teletex-string TeletexString
                (SIZE(1..ub-pds-parameter-length)) OPTIONAL }

extended-network-address INTEGER ::= 22

ExtendedNetworkAddress ::= CHOICE {
   e163-4-address SEQUENCE {
        number [0] NumericString (SIZE (1..ub-e163-4-number-length)),
        sub-address [1] NumericString
                (SIZE (1..ub-e163-4-sub-address-length)) OPTIONAL },
   psap-address [0] PresentationAddress }

PresentationAddress ::= SEQUENCE {
        pSelector       [0] EXPLICIT OCTET STRING OPTIONAL,
        sSelector       [1] EXPLICIT OCTET STRING OPTIONAL,
        tSelector       [2] EXPLICIT OCTET STRING OPTIONAL,
        nAddresses      [3] EXPLICIT SET SIZE (1..MAX) OF OCTET STRING }

terminal-type  INTEGER ::= 23

TerminalType ::= INTEGER {
   telex (3),
   teletex (4),
   g3-facsimile (5),
   g4-facsimile (6),
   ia5-terminal (7),
   videotex (8) } (0..ub-integer-options)

--      Extension Domain-defined Attributes

teletex-domain-defined-attributes INTEGER ::= 6

TeletexDomainDefinedAttributes ::= SEQUENCE SIZE
   (1..ub-domain-defined-attributes) OF TeletexDomainDefinedAttribute

TeletexDomainDefinedAttribute ::= SEQUENCE {
        type TeletexString
               (SIZE (1..ub-domain-defined-attribute-type-length)),
        value TeletexString



Housley, Ford, Polk, & Solo                                    [Page 80]


INTERNET DRAFT                                             June 16, 1998


               (SIZE (1..ub-domain-defined-attribute-value-length)) }

--  specifications of Upper Bounds must be regarded as mandatory
--  from Annex B of ITU-T X.411 Reference Definition of MTS Parameter
--  Upper Bounds

--      Upper Bounds
ub-name INTEGER ::=     32768
ub-common-name  INTEGER ::=     64
ub-locality-name        INTEGER ::=     128
ub-state-name   INTEGER ::=     128
ub-organization-name    INTEGER ::=     64
ub-organizational-unit-name     INTEGER ::=     64
ub-title        INTEGER ::=     64
ub-match        INTEGER ::=     128

ub-emailaddress-length INTEGER ::= 128

ub-common-name-length INTEGER ::= 64
ub-country-name-alpha-length INTEGER ::= 2
ub-country-name-numeric-length INTEGER ::= 3
ub-domain-defined-attributes INTEGER ::= 4
ub-domain-defined-attribute-type-length INTEGER ::= 8
ub-domain-defined-attribute-value-length INTEGER ::= 128
ub-domain-name-length INTEGER ::= 16
ub-extension-attributes INTEGER ::= 256
ub-e163-4-number-length INTEGER ::= 15
ub-e163-4-sub-address-length INTEGER ::= 40
ub-generation-qualifier-length INTEGER ::= 3
ub-given-name-length INTEGER ::= 16
ub-initials-length INTEGER ::= 5
ub-integer-options INTEGER ::= 256
ub-numeric-user-id-length INTEGER ::= 32
ub-organization-name-length INTEGER ::= 64
ub-organizational-unit-name-length INTEGER ::= 32
ub-organizational-units INTEGER ::= 4
ub-pds-name-length INTEGER ::= 16
ub-pds-parameter-length INTEGER ::= 30
ub-pds-physical-address-lines INTEGER ::= 6
ub-postal-code-length INTEGER ::= 16
ub-surname-length INTEGER ::= 40
ub-terminal-id-length INTEGER ::= 24
ub-unformatted-address-length INTEGER ::= 180
ub-x121-address-length INTEGER ::= 16

-- Note - upper bounds on string types, such as TeletexString, are
-- measured in characters.  Excepting PrintableString or IA5String, a
-- significantly greater number of octets will be required to hold



Housley, Ford, Polk, & Solo                                    [Page 81]


INTERNET DRAFT                                             June 16, 1998


-- such a value.  As a minimum, 16 octets, or twice the specified upper
-- bound, whichever is the larger, should be allowed for TeletexString.
-- For UTF8String or UniversalString at least four times the upper
-- bound should be allowed.

END













































Housley, Ford, Polk, & Solo                                    [Page 82]


INTERNET DRAFT                                             June 16, 1998


A.2 Implicit Module 88-style ASN.1

PKIX1Implicit88 {iso(1) identified-organization(3) dod(6) internet(1)
  security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-implicit-88(2)}

DEFINITIONS IMPLICIT TAGS ::=

BEGIN

-- EXPORTS ALL --

IMPORTS
        id-pe, id-qt, id-kp, id-ad, id-qt-unotice, id-qt-cps,
                ORAddress, Name, RelativeDistinguishedName,
                CertificateSerialNumber,
                CertificateList, AlgorithmIdentifier, ub-name,
                Attribute, DirectoryString
                FROM PKIX1Explicit88 {iso(1) identified-organization(3)
                dod(6) internet(1) security(5) mechanisms(5) pkix(7)
                id-mod(0) id-pkix1-explicit(1)};


-- ISO arc for standard certificate and CRL extensions

id-ce OBJECT IDENTIFIER  ::=  {joint-iso-ccitt(2) ds(5) 29}

-- authority key identifier OID and syntax

id-ce-authorityKeyIdentifier OBJECT IDENTIFIER ::=  { id-ce 35 }

AuthorityKeyIdentifier ::= SEQUENCE {
      keyIdentifier             [0] KeyIdentifier            OPTIONAL,
      authorityCertIssuer       [1] GeneralNames             OPTIONAL,
      authorityCertSerialNumber [2] CertificateSerialNumber  OPTIONAL }
    -- authorityCertIssuer and authorityCertSerialNumber must both
    -- be present or both be absent

KeyIdentifier ::= OCTET STRING

-- subject key identifier OID and syntax

id-ce-subjectKeyIdentifier OBJECT IDENTIFIER ::=  { id-ce 14 }

SubjectKeyIdentifier ::= KeyIdentifier

-- key usage extension OID and syntax

id-ce-keyUsage OBJECT IDENTIFIER ::=  { id-ce 15 }



Housley, Ford, Polk, & Solo                                    [Page 83]


INTERNET DRAFT                                             June 16, 1998


KeyUsage ::= BIT STRING {
     digitalSignature        (0),
     nonRepudiation          (1),
     keyEncipherment         (2),
     dataEncipherment        (3),
     keyAgreement            (4),
     keyCertSign             (5),
     cRLSign                 (6) }

-- private key usage period extension OID and syntax

id-ce-privateKeyUsagePeriod OBJECT IDENTIFIER ::=  { id-ce 16 }

PrivateKeyUsagePeriod ::= SEQUENCE {
     notBefore       [0]     GeneralizedTime OPTIONAL,
     notAfter        [1]     GeneralizedTime OPTIONAL }
     -- either notBefore or notAfter must be present

-- certificate policies extension OID and syntax

id-ce-certificatePolicies OBJECT IDENTIFIER ::=  { id-ce 32 }

CertificatePolicies ::= SEQUENCE SIZE (1..MAX) OF PolicyInformation

PolicyInformation ::= SEQUENCE {
     policyIdentifier   CertPolicyId,
     policyQualifiers   SEQUENCE SIZE (1..MAX) OF
             PolicyQualifierInfo OPTIONAL }

CertPolicyId ::= OBJECT IDENTIFIER

PolicyQualifierInfo ::= SEQUENCE {
       policyQualifierId  PolicyQualifierId,
       qualifier        ANY DEFINED BY policyQualifierId }

-- Implementations that recognize additional policy qualifiers must
-- augment the following definition for PolicyQualifierId

PolicyQualifierId ::=
    OBJECT IDENTIFIER ( id-qt-cps | id-qt-unotice )

-- CPS pointer qualifier

id-qt-cps      OBJECT IDENTIFIER ::=  { id-qt 1 }

CPSuri ::= IA5String

-- user notice qualifier



Housley, Ford, Polk, & Solo                                    [Page 84]


INTERNET DRAFT                                             June 16, 1998


id-qt-unotice  OBJECT IDENTIFIER ::=  { id-qt 2 }

UserNotice ::= SEQUENCE {
     noticeRef        NoticeReference OPTIONAL,
     explicitText     DisplayText OPTIONAL}

NoticeReference ::= SEQUENCE {
     organization     DisplayText,
     noticeNumbers    SEQUENCE OF INTEGER }

DisplayText ::= CHOICE {
     visibleString    VisibleString  (SIZE (1..200)),
     bmpString        BMPString      (SIZE (1..200)),
     utf8String       UTF8String     (SIZE (1..200)) }

-- policy mapping extension OID and syntax

id-ce-policyMappings OBJECT IDENTIFIER ::=  { id-ce 33 }

PolicyMappings ::= SEQUENCE SIZE (1..MAX) OF SEQUENCE {
     issuerDomainPolicy      CertPolicyId,
     subjectDomainPolicy     CertPolicyId }

-- subject alternative name extension OID and syntax

id-ce-subjectAltName OBJECT IDENTIFIER ::=  { id-ce 17 }

SubjectAltName ::= GeneralNames

GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName

GeneralName ::= CHOICE {
     otherName                       [0]     AnotherName,
     rfc822Name                      [1]     IA5String,
     dNSName                         [2]     IA5String,
     x400Address                     [3]     ORAddress,
     directoryName                   [4]     Name,
     ediPartyName                    [5]     EDIPartyName,
     uniformResourceIdentifier       [6]     IA5String,
     iPAddress                       [7]     OCTET STRING,
     registeredID                    [8]     OBJECT IDENTIFIER }

-- AnotherName replaces OTHER-NAME ::= TYPE-IDENTIFIER, as
-- TYPE-IDENTIFIER is not supported in the '88 ASN.1 syntax

AnotherName ::= SEQUENCE {
     type-id    OBJECT IDENTIFIER,
     value      [0] EXPLICIT ANY DEFINED BY type-id }



Housley, Ford, Polk, & Solo                                    [Page 85]


INTERNET DRAFT                                             June 16, 1998


EDIPartyName ::= SEQUENCE {
     nameAssigner            [0]     DirectoryString OPTIONAL,
     partyName               [1]     DirectoryString }

-- issuer alternative name extension OID and syntax

id-ce-issuerAltName OBJECT IDENTIFIER ::=  { id-ce 18 }

IssuerAltName ::= GeneralNames

id-ce-subjectDirectoryAttributes OBJECT IDENTIFIER ::=  { id-ce 9 }

SubjectDirectoryAttributes ::= SEQUENCE SIZE (1..MAX) OF Attribute

-- basic constraints extension OID and syntax

id-ce-basicConstraints OBJECT IDENTIFIER ::=  { id-ce 19 }

BasicConstraints ::= SEQUENCE {
     cA                      BOOLEAN DEFAULT FALSE,
     pathLenConstraint       INTEGER (0..MAX) OPTIONAL }

-- name constraints extension OID and syntax

id-ce-nameConstraints OBJECT IDENTIFIER ::=  { id-ce 30 }

NameConstraints ::= SEQUENCE {
     permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
     excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }

GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree

GeneralSubtree ::= SEQUENCE {
     base                    GeneralName,
     minimum         [0]     BaseDistance DEFAULT 0,
     maximum         [1]     BaseDistance OPTIONAL }

BaseDistance ::= INTEGER (0..MAX)

-- policy constraints extension OID and syntax

id-ce-policyConstraints OBJECT IDENTIFIER ::=  { id-ce 36 }

PolicyConstraints ::= SEQUENCE SIZE (1..MAX) OF SEQUENCE {
     requireExplicitPolicy           [0] SkipCerts OPTIONAL,
     inhibitPolicyMapping            [1] SkipCerts OPTIONAL }

SkipCerts ::= INTEGER (0..MAX)



Housley, Ford, Polk, & Solo                                    [Page 86]


INTERNET DRAFT                                             June 16, 1998


-- CRL distribution points extension OID and syntax

id-ce-cRLDistributionPoints     OBJECT IDENTIFIER  ::=  {id-ce 31}

CRLDistPointsSyntax ::= SEQUENCE SIZE (1..MAX) OF DistributionPoint

DistributionPoint ::= SEQUENCE {
     distributionPoint       [0]     DistributionPointName OPTIONAL,
     reasons                 [1]     ReasonFlags OPTIONAL,
     cRLIssuer               [2]     GeneralNames OPTIONAL }

DistributionPointName ::= CHOICE {
     fullName                [0]     GeneralNames,
     nameRelativeToCRLIssuer [1]     RelativeDistinguishedName }

ReasonFlags ::= BIT STRING {
     unused                  (0),
     keyCompromise           (1),
     cACompromise            (2),
     affiliationChanged      (3),
     superseded              (4),
     cessationOfOperation    (5),
     certificateHold         (6) }

-- extended key usage extension OID and syntax

id-ce-extKeyUsage OBJECT IDENTIFIER ::= {id-ce 37}

ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId

KeyPurposeId ::= OBJECT IDENTIFIER

-- extended key purpose OIDs
id-kp-serverAuth      OBJECT IDENTIFIER ::= { id-kp 1 }
id-kp-clientAuth      OBJECT IDENTIFIER ::= { id-kp 2 }
id-kp-codeSigning     OBJECT IDENTIFIER ::= { id-kp 3 }
id-kp-emailProtection OBJECT IDENTIFIER ::= { id-kp 4 }
id-kp-ipsecEndSystem  OBJECT IDENTIFIER ::= { id-kp 5 }
id-kp-ipsecTunnel     OBJECT IDENTIFIER ::= { id-kp 6 }
id-kp-ipsecUser       OBJECT IDENTIFIER ::= { id-kp 7 }
id-kp-timeStamping    OBJECT IDENTIFIER ::= { id-kp 8 }

-- CRL number extension OID and syntax

id-ce-cRLNumber OBJECT IDENTIFIER ::= { id-ce 20 }

CRLNumber ::= INTEGER (0..MAX)




Housley, Ford, Polk, & Solo                                    [Page 87]


INTERNET DRAFT                                             June 16, 1998


-- issuing distribution point extension OID and syntax

id-ce-issuingDistributionPoint OBJECT IDENTIFIER ::= { id-ce 28 }

IssuingDistributionPoint ::= SEQUENCE {
     distributionPoint       [0] DistributionPointName OPTIONAL,
     onlyContainsUserCerts   [1] BOOLEAN DEFAULT FALSE,
     onlyContainsCACerts     [2] BOOLEAN DEFAULT FALSE,
     onlySomeReasons         [3] ReasonFlags OPTIONAL,
     indirectCRL             [4] BOOLEAN DEFAULT FALSE }


id-ce-deltaCRLIndicator OBJECT IDENTIFIER ::= { id-ce 27 }

-- deltaCRLIndicator ::= BaseCRLNumber

BaseCRLNumber ::= CRLNumber

-- CRL reasons extension OID and syntax

id-ce-cRLReasons OBJECT IDENTIFIER ::= { id-ce 21 }

CRLReason ::= ENUMERATED {
     unspecified             (0),
     keyCompromise           (1),
     cACompromise            (2),
     affiliationChanged      (3),
     superseded              (4),
     cessationOfOperation    (5),
     certificateHold         (6),
     removeFromCRL           (8) }

-- certificate issuer CRL entry extension OID and syntax

id-ce-certificateIssuer OBJECT IDENTIFIER ::= { id-ce 29 }

CertificateIssuer ::= GeneralNames

-- hold instruction extension OID and syntax

id-ce-holdInstructionCode OBJECT IDENTIFIER ::= { id-ce 23 }

HoldInstructionCode ::= OBJECT IDENTIFIER

-- ANSI x9 holdinstructions

-- ANSI x9 arc holdinstruction arc
holdInstruction OBJECT IDENTIFIER ::=



Housley, Ford, Polk, & Solo                                    [Page 88]


INTERNET DRAFT                                             June 16, 1998


            {joint-iso-itu-t(2) member-body(2) us(840) x9cm(10040) 2}

-- ANSI X9 holdinstructions referenced by this standard
id-holdinstruction-none OBJECT IDENTIFIER  ::=
                {holdInstruction 1} -- deprecated
id-holdinstruction-callissuer OBJECT IDENTIFIER ::=
                {holdInstruction 2}
id-holdinstruction-reject OBJECT IDENTIFIER ::=
                {holdInstruction 3}

-- invalidty date CRL entry extension OID and syntax

id-ce-invalidityDate OBJECT IDENTIFIER ::= { id-ce 24 }

InvalidityDate ::=  GeneralizedTime

END


































Housley, Ford, Polk, & Solo                                    [Page 89]


INTERNET DRAFT                                             June 16, 1998


Appendix B. 1993 ASN.1 Structures and OIDs


B.1 1993 Explicitly Tagged Module

PKIX1Explicit93 {iso(1) identified-organization(3) dod(6) internet(1)
   security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-explicit-93(3)}


DEFINITIONS EXPLICIT TAGS ::=

BEGIN

-- EXPORTS ALL --

IMPORTS
        authorityKeyIdentifier, subjectKeyIdentifier, keyUsage,
           extendedKeyUsage,privateKeyUsagePeriod, certificatePolicies,
           policyMappings, subjectAltName, issuerAltName,
           basicConstraints, nameConstraints, policyConstraints,
           cRLDistributionPoints, subjectDirectoryAttributes,
           cRLNumber, reasonCode, instructionCode, invalidityDate,
           issuingDistributionPoint, certificateIssuer,
           deltaCRLIndicator, authorityInfoAccess, id-ce
           FROM PKIX1Implicit93 {iso(1) identified-organization(3)
           dod(6) internet(1) security(5) mechanisms(5) pkix(7)
           id-mod(0) id-pkix1-implicit-93(4)} ;

--
                   --  Locally defined OIDs  --

id-pkix  OBJECT IDENTIFIER  ::=
         { iso(1) identified-organization(3) dod(6) internet(1)
                    security(5) mechanisms(5) pkix(7) }

-- PKIX arcs
-- arc for private certificate extensions
id-pe OBJECT IDENTIFIER  ::=  { id-pkix 1 }
 -- arc for policy qualifier types
id-qt OBJECT IDENTIFIER ::= { id-pkix 2 }
-- arc for extended key purpose OIDS
id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }
-- arc for access descriptors
id-ad OBJECT IDENTIFIER ::= { id-pkix 48 }

-- policyQualifierIds for Internet policy qualifiers
id-qt-cps      OBJECT IDENTIFIER ::=  { id-qt 1 }
        -- OID for CPS qualifier



Housley, Ford, Polk, & Solo                                    [Page 90]


INTERNET DRAFT                                             June 16, 1998


id-qt-unotice  OBJECT IDENTIFIER ::=  { id-qt 2 }
        -- OID for user notice qualifier

-- based on excerpts from AuthenticationFramework
--    {joint-iso-ccitt ds(5) modules(1) authenticationFramework(7) 2}

               -- Public Key Certificate --

Certificate            ::=   SIGNED { SEQUENCE {
   version                 [0]   Version DEFAULT v1,
   serialNumber                  CertificateSerialNumber,
   signature                     AlgorithmIdentifier,
   issuer                        Name,
   validity                      Validity,
   subject                       Name,
   subjectPublicKeyInfo          SubjectPublicKeyInfo,
   issuerUniqueIdentifier  [1]   IMPLICIT UniqueIdentifier OPTIONAL,
                              ---if present, version must be v2 or v3--
   subjectUniqueIdentifier [2]   IMPLICIT UniqueIdentifier OPTIONAL,
                              ---if present, version must be v2 or v3--
   extensions              [3]   Extensions OPTIONAL
                              --if present, version must be v3--}  }

UniqueIdentifier        ::=  BIT STRING

Version                 ::=  INTEGER { v1(0), v2(1), v3(2) }

CertificateSerialNumber ::=  INTEGER

Validity                        ::=     SEQUENCE {
   notBefore            Time,
   notAfter             Time }

Time ::= CHOICE {
        utcTime         UTCTime,
        generalTime             GeneralizedTime }

SubjectPublicKeyInfo    ::=     SEQUENCE{
   algorithm            AlgorithmIdentifier,
   subjectPublicKey     BIT STRING}

Extensions        ::=   SEQUENCE SIZE (1..MAX) OF Extension

Extension         ::=   SEQUENCE {
   extnId            EXTENSION.&id ({ExtensionSet}),
   critical          BOOLEAN DEFAULT FALSE,
   extnValue         OCTET STRING }
                -- contains a DER encoding of a value of type



Housley, Ford, Polk, & Solo                                    [Page 91]


INTERNET DRAFT                                             June 16, 1998


                -- &ExtnType for the
                -- extension object identified by extnId --

-- The following information object set is defined to constrain the
-- set of legal certificate extensions.

ExtensionSet    EXTENSION       ::=  { authorityKeyIdentifier |
                                            subjectKeyIdentifier |
                                            keyUsage |
                                            extendedKeyUsage |
                                            privateKeyUsagePeriod |
                                            certificatePolicies |
                                            policyMappings |
                                            subjectAltName |
                                            issuerAltName |
                                            basicConstraints |
                                            nameConstraints |
                                            policyConstraints |
                                            cRLDistributionPoints |
                                            subjectDirectoryAttributes |
                                            authorityInfoAccess }

EXTENSION       ::=     CLASS {
   &id          OBJECT IDENTIFIER UNIQUE,
   &ExtnType }
WITH SYNTAX  {
   SYNTAX               &ExtnType
   IDENTIFIED BY        &id }

                  -- Certificate Revocation List --

CertificateList ::=    SIGNED { SEQUENCE {
   version                Version  OPTIONAL, -- if present, must be v2
   signature              AlgorithmIdentifier,
   issuer                 Name,
   thisUpdate             Time,
   nextUpdate             Time OPTIONAL,
   revokedCertificates    SEQUENCE OF SEQUENCE {
   userCertificate        CertificateSerialNumber,
   revocationDate         Time,
   crlEntryExtensions     EntryExtensions OPTIONAL } OPTIONAL,
   crlExtensions          [0]   CRLExtensions OPTIONAL }}

CRLExtensions        ::=        SEQUENCE SIZE (1..MAX) OF CRLExtension

CRLExtension         ::=        SEQUENCE {
   extnId            EXTENSION.&id ({CRLExtensionSet}),
   critical          BOOLEAN DEFAULT FALSE,



Housley, Ford, Polk, & Solo                                    [Page 92]


INTERNET DRAFT                                             June 16, 1998


   extnValue         OCTET STRING }
                -- contains a DER encoding of a value of type
                -- &ExtnType for the
                -- extension object identified by extnId --

-- The following information object set is defined to constrain the
-- set of legal CRL extensions.

CRLExtensionSet EXTENSION       ::=     { authorityKeyIdentifier |
                                             issuerAltName |
                                             cRLNumber |
                                             deltaCRLIndicator |
                                             issuingDistributionPoint }

-- EXTENSION defined above for certificates

EntryExtensions        ::=      SEQUENCE SIZE (1..MAX) OF EntryExtension

EntryExtension         ::=      SEQUENCE {
   extnId            EXTENSION.&id ({EntryExtensionSet}),
   critical          BOOLEAN DEFAULT FALSE,
   extnValue         OCTET STRING }
                -- contains a DER encoding of a value of type
                -- &ExtnType for the
                -- extension object identified by extnId --

-- The following information object set is defined to constrain the
-- set of legal CRL entry extensions.

EntryExtensionSet       EXTENSION       ::=     { reasonCode |
                                                instructionCode |
                                                invalidityDate |
                                                certificateIssuer }

         -- information object classes used in the defintion --
                    -- of certificates and CRLs --

-- Parameterized Type SIGNED --

  SIGNED { ToBeSigned } ::= SEQUENCE {
     toBeSigned  ToBeSigned,
     algorithm   AlgorithmIdentifier,
     signature   BIT STRING
  }

-- Definition of AlgorithmIdentifier
-- ISO definition was:
--



Housley, Ford, Polk, & Solo                                    [Page 93]


INTERNET DRAFT                                             June 16, 1998


-- AlgorithmIdentifier     ::=  SEQUENCE {
--   algorithm          ALGORITHM.&id({SupportedAlgorithms}),
--   parameters         ALGORITHM.&Type({SupportedAlgorithms}
--                                         { @algorithm}) OPTIONAL }
-- Definition of ALGORITHM
-- ALGORITHM    ::=     TYPE-IDENTIFIER

-- The following PKIX definition replaces the X.509 definition
--

AlgorithmIdentifier     ::=  SEQUENCE {
   algorithm            ALGORITHM-ID.&id({SupportedAlgorithms}),
   parameters           ALGORITHM-ID.&Type({SupportedAlgorithms}
                                           { @algorithm}) OPTIONAL }

-- Definition of ALGORITHM-ID

 ALGORITHM-ID ::= CLASS {
     &id    OBJECT IDENTIFIER UNIQUE,
     &Type  OPTIONAL
  }
     WITH SYNTAX { OID &id [PARMS &Type] }

-- The definition of SupportedAlgorithms may be modified as this
-- document does not specify a mandatory algorithm set.  In addition,
-- the set is specified as extensible, since additional algorithms
-- may be supported

SupportedAlgorithms     ALGORITHM-ID  ::=       { ..., -- extensible
                                            RsaPublicKey |
                                            RsaSHA-1  |
                                            RsaMD5 |
                                            RsaMD2 |
                                            DssPublicKey |
                                            DsaSHA-1 |
                                            Dhpublicnumber }

-- OIDs and parameter structures for ALGORITHM-IDs used
-- in this specification

RsaPublicKey ALGORITHM-ID ::= { OID rsaEncryption PARMS NULL }

RsaSHA-1 ALGORITHM-ID ::= { OID sha1WithRSAEncryption PARMS NULL }

RsaMD5 ALGORITHM-ID ::= { OID md5WithRSAEncryption PARMS NULL  }

RsaMD2 ALGORITHM-ID ::= { OID md2WithRSAEncryption PARMS NULL  }




Housley, Ford, Polk, & Solo                                    [Page 94]


INTERNET DRAFT                                             June 16, 1998


DssPublicKey ALGORITHM-ID ::= { OID id-dsa PARMS Dss-Parms }

DsaSHA-1 ALGORITHM-ID ::= { OID id-dsa-with-sha1 PARMS NULL }

DhPublicKey ALGORITHM-ID ::= {OID dhpublicnumber PARMS DomainParameters}

-- algorithm identifiers and parameter structures

pkcs-1 OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 }

rsaEncryption OBJECT IDENTIFIER ::=  { pkcs-1 1 }

md2WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 2 }

md5WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 4 }

sha1WithRSAEncryption OBJECT IDENTIFIER  ::=  { pkcs-1 5 }

id-dsa-with-sha1 OBJECT IDENTIFIER ::=  {
     iso(1) member-body(2) us(840) x9-57 (10040) x9algorithm(4) 3 }

Dss-Sig-Value  ::=  SEQUENCE  {
     r       INTEGER,
     s       INTEGER  }

dhpublicnumber OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-x942(10046) number-type(2) 1 }

DomainParameters ::= SEQUENCE {
     p       INTEGER, -- odd prime, p=jq +1
     g       INTEGER, -- generator, g
     q       INTEGER, -- factor of p-1
     j       INTEGER OPTIONAL, -- subgroup factor, j>= 2
     validationParms  ValidationParms OPTIONAL }

ValidationParms ::= SEQUENCE {
     seed             BIT STRING,
     pgenCounter      INTEGER }

id-dsa OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) x9-57(10040) x9algorithm(4) 1 }

Dss-Parms  ::=  SEQUENCE  {
     p             INTEGER,
     q             INTEGER,
     g             INTEGER  }




Housley, Ford, Polk, & Solo                                    [Page 95]


INTERNET DRAFT                                             June 16, 1998


     -- The ASN.1 in this section supports the Name type
     -- and the directoryAttribute extension

-- attribute data types --

Attribute       ::=     SEQUENCE {
        type            ATTRIBUTE.&id ({SupportedAttributes}),
        values  SET SIZE (1 .. MAX) OF ATTRIBUTE.&Type
                        ({SupportedAttributes}{@type})}

AttributeTypeAndValue           ::=     SEQUENCE {
        type            ATTRIBUTE.&id ({SupportedAttributes}),
        value   ATTRIBUTE.&Type ({SupportedAttributes}{@type})}

-- naming data types --

Name            ::=     CHOICE { -- only one possibility for now --
                                        rdnSequence  RDNSequence }

RDNSequence ::= SEQUENCE OF RelativeDistinguishedName

RelativeDistinguishedName       ::=
                SET SIZE (1 .. MAX) OF AttributeTypeAndValue

ID     ::=    OBJECT IDENTIFIER

-- ATTRIBUTE information object class specification
--  Note: This has been greatly simplified for PKIX !!

ATTRIBUTE               ::=     CLASS {
        &Type,
        &id                     OBJECT IDENTIFIER UNIQUE }
WITH SYNTAX {
        WITH SYNTAX &Type ID &id }

-- suggested naming attributes
--      Definition of the following information object set may be
--    augmented to meet local requirements.  Note that deleting
--    members of the set may prevent interoperability with
--    conforming implementations.

SupportedAttributes     ATTRIBUTE       ::=     {
              name | commonName | surname | givenName | initials |
              generationQualifier | dnQualifier | countryName |
              localityName | stateOrProvinceName | organizationName |
              organizationalUnitName | title | pkcs9email }

name ATTRIBUTE  ::=     {



Housley, Ford, Polk, & Solo                                    [Page 96]


INTERNET DRAFT                                             June 16, 1998


        WITH SYNTAX                     DirectoryString { ub-name }
        ID                                      id-at-name }

commonName ATTRIBUTE    ::=     {
        WITH SYNTAX                     DirectoryString {ub-common-name}
        ID                                      id-at-commonName }

surname ATTRIBUTE       ::=             {
        WITH SYNTAX                     DirectoryString {ub-name}
        ID                                      id-at-surname }

givenName ATTRIBUTE     ::=             {
        WITH SYNTAX                     DirectoryString {ub-name}
        ID                                      id-at-givenName }

initials ATTRIBUTE      ::=             {
        WITH SYNTAX                     DirectoryString {ub-name}
        ID                                      id-at-initials }

generationQualifier ATTRIBUTE   ::=             {
        WITH SYNTAX                     DirectoryString {ub-name}
        ID                              id-at-generationQualifier}

dnQualifier ATTRIBUTE   ::=     {
        WITH SYNTAX                     PrintableString
        ID                                      id-at-dnQualifier }


countryName ATTRIBUTE   ::=     {
        WITH SYNTAX                     PrintableString (SIZE (2))
                                             -- IS 3166 codes only
        ID                                      id-at-countryName }

localityName ATTRIBUTE  ::=     {
        WITH SYNTAX             DirectoryString {ub-locality-name}
        ID                      id-at-localityName }

stateOrProvinceName ATTRIBUTE   ::=     {
        WITH SYNTAX             DirectoryString {ub-state-name}
        ID                      id-at-stateOrProvinceName }

organizationName ATTRIBUTE      ::=     {
        WITH SYNTAX             DirectoryString {ub-organization-name}
        ID                      id-at-organizationName }

organizationalUnitName ATTRIBUTE        ::=     {
        WITH SYNTAX  DirectoryString {ub-organizational-unit-name}
        ID                      id-at-organizationalUnitName }



Housley, Ford, Polk, & Solo                                    [Page 97]


INTERNET DRAFT                                             June 16, 1998


title ATTRIBUTE ::=                     {
        WITH SYNTAX             DirectoryString {ub-title}
        ID                      id-at-title }

 -- Legacy attributes

pkcs9email ATTRIBUTE ::= {
        WITH SYNTAX                     PHGString,
        ID                              emailAddress }

PHGString ::= IA5String (SIZE(1..ub-emailaddress-length))

pkcs-9 OBJECT IDENTIFIER ::=
       { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 9 }

emailAddress OBJECT IDENTIFIER ::= { pkcs-9 1 }

    -- object identifiers for Name type and directory attribute support

-- Object identifier assignments --

id-at   OBJECT IDENTIFIER       ::=     {joint-iso-ccitt(2) ds(5) 4}

-- Attributes --

id-at-commonName        OBJECT IDENTIFIER       ::=     {id-at 3}
id-at-surname           OBJECT IDENTIFIER       ::=     {id-at 4}
id-at-countryName       OBJECT IDENTIFIER       ::=     {id-at 6}
id-at-localityName      OBJECT IDENTIFIER       ::=     {id-at 7}
id-at-stateOrProvinceName     OBJECT IDENTIFIER ::=     {id-at 8}
id-at-organizationName        OBJECT IDENTIFIER ::=     {id-at 10}
id-at-organizationalUnitName  OBJECT IDENTIFIER ::=     {id-at 11}
id-at-title             OBJECT IDENTIFIER       ::=     {id-at 12}
id-at-name              OBJECT IDENTIFIER       ::=     {id-at 41}
id-at-givenName         OBJECT IDENTIFIER       ::=     {id-at 42}
id-at-initials          OBJECT IDENTIFIER       ::=     {id-at 43}
id-at-generationQualifier     OBJECT IDENTIFIER ::=     {id-at 44}
id-at-dnQualifier       OBJECT IDENTIFIER       ::=     {id-at 46}

-- Directory string type, used extensively in Name types --

DirectoryString { INTEGER:maxSize } ::= CHOICE {
        teletexString           TeletexString (SIZE (1..maxSize)),
        printableString         PrintableString (SIZE (1..maxSize)),
        universalString         UniversalString (SIZE (1..maxSize)),
        bmpString               BMPString (SIZE(1..maxSize)),
        utf8String                      UTF8String (SIZE(1..maxSize))
                            }



Housley, Ford, Polk, & Solo                                    [Page 98]


INTERNET DRAFT                                             June 16, 1998


     -- End of ASN.1 for Name type and directory attribute support --

     -- The ASN.1 in this section supports X.400 style names   --
     -- for implementations that use the x400Address component --
     -- of GeneralName.                                        --

ORAddress ::= SEQUENCE {
   built-in-standard-attributes BuiltInStandardAttributes,
   built-in-domain-defined-attributes
                        BuiltInDomainDefinedAttributes OPTIONAL,
   -- see also teletex-domain-defined-attributes
   extension-attributes ExtensionAttributes OPTIONAL }

--  The OR-address is semantically absent from the OR-name if the
--  built-in-standard-attribute sequence is empty and the
--  built-in-domain-defined-attributes and extension-attributes are
--  both omitted.

--      Built-in Standard Attributes

BuiltInStandardAttributes ::= SEQUENCE {
   country-name CountryName OPTIONAL,
   administration-domain-name AdministrationDomainName OPTIONAL,
   network-address      [0] NetworkAddress OPTIONAL,
   -- see also extended-network-address
   terminal-identifier  [1] TerminalIdentifier OPTIONAL,
   private-domain-name  [2] PrivateDomainName OPTIONAL,
   organization-name    [3] OrganizationName OPTIONAL,
   -- see also teletex-organization-name
   numeric-user-identifier      [4] NumericUserIdentifier OPTIONAL,
   personal-name        [5] PersonalName OPTIONAL,
   -- see also teletex-personal-name
   organizational-unit-names    [6] OrganizationalUnitNames OPTIONAL
   -- see also teletex-organizational-unit-names -- }

CountryName ::= [APPLICATION 1] CHOICE {
   x121-dcc-code NumericString
                (SIZE (ub-country-name-numeric-length)),
   iso-3166-alpha2-code PrintableString
                (SIZE (ub-country-name-alpha-length)) }

AdministrationDomainName ::= [APPLICATION 2] CHOICE {
   numeric NumericString (SIZE (0..ub-domain-name-length)),
   printable PrintableString (SIZE (0..ub-domain-name-length)) }

NetworkAddress ::= X121Address
-- see also extended-network-address




Housley, Ford, Polk, & Solo                                    [Page 99]


INTERNET DRAFT                                             June 16, 1998


X121Address ::= NumericString (SIZE (1..ub-x121-address-length))

TerminalIdentifier ::= PrintableString (SIZE (1..ub-terminal-id-length))

PrivateDomainName ::= CHOICE {
   numeric NumericString (SIZE (1..ub-domain-name-length)),
   printable PrintableString (SIZE (1..ub-domain-name-length)) }

OrganizationName ::= PrintableString
                           (SIZE (1..ub-organization-name-length))
-- see also teletex-organization-name

NumericUserIdentifier ::= NumericString
                             (SIZE (1..ub-numeric-user-id-length))

PersonalName ::= SET {
   surname    [0] PrintableString (SIZE (1..ub-surname-length)),
   given-name [1] PrintableString
                        (SIZE (1..ub-given-name-length)) OPTIONAL,
   initials   [2] PrintableString
                        (SIZE (1..ub-initials-length)) OPTIONAL,
   generation-qualifier [3] PrintableString
                (SIZE (1..ub-generation-qualifier-length)) OPTIONAL}
-- see also teletex-personal-name

OrganizationalUnitNames ::= SEQUENCE SIZE (1..ub-organizational-units)
                                        OF OrganizationalUnitName
-- see also teletex-organizational-unit-names

OrganizationalUnitName ::= PrintableString (SIZE
                        (1..ub-organizational-unit-name-length))

--      Built-in Domain-defined Attributes
BuiltInDomainDefinedAttributes ::= SEQUENCE SIZE
                                (1..ub-domain-defined-attributes) OF
                                BuiltInDomainDefinedAttribute

BuiltInDomainDefinedAttribute ::= SEQUENCE {
   type PrintableString (SIZE
                (1..ub-domain-defined-attribute-type-length)),
   value PrintableString (SIZE
                (1..ub-domain-defined-attribute-value-length)) }

--      Extension Attributes

ExtensionAttributes ::= SET SIZE (1..ub-extension-attributes)
                                        OF ExtensionAttribute
ExtensionAttribute ::= SEQUENCE {



Housley, Ford, Polk, & Solo                                   [Page 100]


INTERNET DRAFT                                             June 16, 1998


        extension-attribute-type [0] EXTENSION-ATTRIBUTE.&id
                                        ({ExtensionAttributeTable}),
        extension-attribute-value [1] EXTENSION-ATTRIBUTE.&Type
             ({ExtensionAttributeTable} {@extension-attribute-type}) }

EXTENSION-ATTRIBUTE ::= CLASS {
        &id     INTEGER (0..ub-extension-attributes) UNIQUE,
        &Type }
WITH SYNTAX {&Type IDENTIFIED BY &id}

ExtensionAttributeTable EXTENSION-ATTRIBUTE ::= {
        common-name |
        teletex-common-name |
        teletex-organization-name |
        teletex-personal-name |
        teletex-organizational-unit-names |
        teletex-domain-defined-attributes |
        pds-name |
        physical-delivery-country-name |
        postal-code |
        physical-delivery-office-name |
        physical-delivery-office-number |
        extension-OR-address-components |
        physical-delivery-personal-name |
        physical-delivery-organization-name |
        extension-physical-delivery-address-components |
        unformatted-postal-address |
        street-address |
        post-office-box-address |
        poste-restante-address |
        unique-postal-name |
        local-postal-attributes |
        extended-network-address |
        terminal-type }

--      Extension Standard Attributes

common-name EXTENSION-ATTRIBUTE ::= {CommonName IDENTIFIED BY 1}

CommonName ::= PrintableString (SIZE (1..ub-common-name-length))

teletex-common-name EXTENSION-ATTRIBUTE ::=
                {TeletexCommonName IDENTIFIED BY 2}

TeletexCommonName ::= TeletexString (SIZE (1..ub-common-name-length))

teletex-organization-name EXTENSION-ATTRIBUTE ::=
                {TeletexOrganizationName IDENTIFIED BY 3}



Housley, Ford, Polk, & Solo                                   [Page 101]


INTERNET DRAFT                                             June 16, 1998


TeletexOrganizationName ::=
                TeletexString (SIZE (1..ub-organization-name-length))

teletex-personal-name EXTENSION-ATTRIBUTE ::=
                {TeletexPersonalName IDENTIFIED BY 4}

TeletexPersonalName ::= SET {
   surname [0] TeletexString (SIZE (1..ub-surname-length)),
   given-name [1] TeletexString
                (SIZE (1..ub-given-name-length)) OPTIONAL,
   initials [2] TeletexString (SIZE (1..ub-initials-length)) OPTIONAL,
   generation-qualifier [3] TeletexString (SIZE
                (1..ub-generation-qualifier-length)) OPTIONAL }

teletex-organizational-unit-names EXTENSION-ATTRIBUTE ::=
   {TeletexOrganizationalUnitNames IDENTIFIED BY 5}

TeletexOrganizationalUnitNames ::= SEQUENCE SIZE
        (1..ub-organizational-units) OF TeletexOrganizationalUnitName

TeletexOrganizationalUnitName ::= TeletexString
                        (SIZE (1..ub-organizational-unit-name-length))

pds-name EXTENSION-ATTRIBUTE ::= {PDSName IDENTIFIED BY 7}

PDSName ::= PrintableString (SIZE (1..ub-pds-name-length))

physical-delivery-country-name EXTENSION-ATTRIBUTE ::=
   {PhysicalDeliveryCountryName IDENTIFIED BY 8}

PhysicalDeliveryCountryName ::= CHOICE {
   x121-dcc-code NumericString (SIZE (ub-country-name-numeric-length)),
   iso-3166-alpha2-code PrintableString
                        (SIZE (ub-country-name-alpha-length)) }

postal-code EXTENSION-ATTRIBUTE ::= {PostalCode IDENTIFIED BY 9}

PostalCode ::= CHOICE {
   numeric-code NumericString (SIZE (1..ub-postal-code-length)),
   printable-code PrintableString (SIZE (1..ub-postal-code-length)) }

physical-delivery-office-name EXTENSION-ATTRIBUTE ::=
                        {PhysicalDeliveryOfficeName IDENTIFIED BY 10}

PhysicalDeliveryOfficeName ::= PDSParameter

physical-delivery-office-number EXTENSION-ATTRIBUTE ::=
   {PhysicalDeliveryOfficeNumber IDENTIFIED BY 11}



Housley, Ford, Polk, & Solo                                   [Page 102]


INTERNET DRAFT                                             June 16, 1998


PhysicalDeliveryOfficeNumber ::= PDSParameter

extension-OR-address-components EXTENSION-ATTRIBUTE ::=
   {ExtensionORAddressComponents IDENTIFIED BY 12}

ExtensionORAddressComponents ::= PDSParameter

physical-delivery-personal-name EXTENSION-ATTRIBUTE ::=
   {PhysicalDeliveryPersonalName IDENTIFIED BY 13}

PhysicalDeliveryPersonalName ::= PDSParameter

physical-delivery-organization-name EXTENSION-ATTRIBUTE ::=
   {PhysicalDeliveryOrganizationName IDENTIFIED BY 14}

PhysicalDeliveryOrganizationName ::= PDSParameter

extension-physical-delivery-address-components EXTENSION-ATTRIBUTE ::=
   {ExtensionPhysicalDeliveryAddressComponents IDENTIFIED BY 15}

ExtensionPhysicalDeliveryAddressComponents ::= PDSParameter

unformatted-postal-address EXTENSION-ATTRIBUTE ::=
                        {UnformattedPostalAddress IDENTIFIED BY 16}

UnformattedPostalAddress ::= SET {
   printable-address SEQUENCE SIZE (1..ub-pds-physical-address-lines) OF
           PrintableString (SIZE (1..ub-pds-parameter-length)) OPTIONAL,
   teletex-string TeletexString (SIZE
                         (1..ub-unformatted-address-length)) OPTIONAL }

street-address EXTENSION-ATTRIBUTE ::=
                {StreetAddress IDENTIFIED BY 17}

StreetAddress ::= PDSParameter

post-office-box-address EXTENSION-ATTRIBUTE ::=
                {PostOfficeBoxAddress IDENTIFIED BY 18}

PostOfficeBoxAddress ::= PDSParameter

poste-restante-address EXTENSION-ATTRIBUTE ::=
                {PosteRestanteAddress IDENTIFIED BY 19}

PosteRestanteAddress ::= PDSParameter

unique-postal-name EXTENSION-ATTRIBUTE ::=
                {UniquePostalName IDENTIFIED BY 20}



Housley, Ford, Polk, & Solo                                   [Page 103]


INTERNET DRAFT                                             June 16, 1998


UniquePostalName ::= PDSParameter

local-postal-attributes EXTENSION-ATTRIBUTE ::=
                {LocalPostalAttributes IDENTIFIED BY 21}

LocalPostalAttributes ::= PDSParameter

PDSParameter ::= SET {
   printable-string PrintableString
            (SIZE(1..ub-pds-parameter-length)) OPTIONAL,
   teletex-string TeletexString
            (SIZE(1..ub-pds-parameter-length)) OPTIONAL }

extended-network-address EXTENSION-ATTRIBUTE ::=
                {ExtendedNetworkAddress IDENTIFIED BY 22}

ExtendedNetworkAddress ::= CHOICE {
        e163-4-address SEQUENCE {
                number [0] NumericString
                   (SIZE (1..ub-e163-4-number-length)),
                sub-address [1] NumericString
                   (SIZE (1..ub-e163-4-sub-address-length)) OPTIONAL},
        psap-address [0] PresentationAddress }

PresentationAddress ::= SEQUENCE {
        pSelector       [0] EXPLICIT OCTET STRING OPTIONAL,
        sSelector       [1] EXPLICIT OCTET STRING OPTIONAL,
        tSelector       [2] EXPLICIT OCTET STRING OPTIONAL,
        nAddresses      [3] EXPLICIT SET SIZE (1..MAX) OF OCTET STRING}


terminal-type EXTENSION-ATTRIBUTE ::= {TerminalType IDENTIFIED BY 23}

TerminalType ::= INTEGER {
   telex (3),
   teletex (4),
   g3-facsimile (5),
   g4-facsimile (6),
   ia5-terminal (7),
   videotex (8) } (0..ub-integer-options)

--      Extension Domain-defined Attributes

teletex-domain-defined-attributes EXTENSION-ATTRIBUTE ::=
   {TeletexDomainDefinedAttributes IDENTIFIED BY 6}

TeletexDomainDefinedAttributes ::= SEQUENCE SIZE
   (1..ub-domain-defined-attributes) OF TeletexDomainDefinedAttribute



Housley, Ford, Polk, & Solo                                   [Page 104]


INTERNET DRAFT                                             June 16, 1998


TeletexDomainDefinedAttribute ::= SEQUENCE {
    type TeletexString
         (SIZE (1..ub-domain-defined-attribute-type-length)),
    value TeletexString
         (SIZE (1..ub-domain-defined-attribute-value-length)) }

--  specifications of Upper Bounds
--  must be regarded as mandatory
--  from Annex B of ITU-T X.411
--  Reference Definition of MTS Parameter Upper Bounds

--      Upper Bounds
ub-name INTEGER ::=     32768
ub-common-name  INTEGER ::=     64
ub-locality-name        INTEGER ::=     128
ub-state-name   INTEGER ::=     128
ub-organization-name    INTEGER ::=     64
ub-organizational-unit-name     INTEGER ::=     64
ub-title        INTEGER ::=     64
ub-match        INTEGER ::=     128

ub-emailaddress-length INTEGER ::= 128

ub-common-name-length INTEGER ::= 64
ub-country-name-alpha-length INTEGER ::= 2
ub-country-name-numeric-length INTEGER ::= 3
ub-domain-defined-attributes INTEGER ::= 4
ub-domain-defined-attribute-type-length INTEGER ::= 8
ub-domain-defined-attribute-value-length INTEGER ::= 128
ub-domain-name-length INTEGER ::= 16
ub-extension-attributes INTEGER ::= 256
ub-e163-4-number-length INTEGER ::= 15
ub-e163-4-sub-address-length INTEGER ::= 40
ub-generation-qualifier-length INTEGER ::= 3
ub-given-name-length INTEGER ::= 16
ub-initials-length INTEGER ::= 5
ub-integer-options INTEGER ::= 256
ub-numeric-user-id-length INTEGER ::= 32
ub-organization-name-length INTEGER ::= 64
ub-organizational-unit-name-length INTEGER ::= 32
ub-organizational-units INTEGER ::= 4
ub-pds-name-length INTEGER ::= 16
ub-pds-parameter-length INTEGER ::= 30
ub-pds-physical-address-lines INTEGER ::= 6
ub-postal-code-length INTEGER ::= 16
ub-surname-length INTEGER ::= 40
ub-terminal-id-length INTEGER ::= 24
ub-unformatted-address-length INTEGER ::= 180



Housley, Ford, Polk, & Solo                                   [Page 105]


INTERNET DRAFT                                             June 16, 1998


ub-x121-address-length INTEGER ::= 16

-- Note - upper bounds on TeletexString are measured in characters.
-- A significantly greater number of octets will be required to hold
-- such a value.  As a minimum, 16 octets, or twice the specified upper
-- bound, whichever is the larger, should be allowed.

END











































Housley, Ford, Polk, & Solo                                   [Page 106]


INTERNET DRAFT                                             June 16, 1998


B.2 1993 Implicitly Tagged Module


PKIX1Implicit93  {iso(1) identified-organization(3) dod(6) internet(1)
   security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-implicit-93(4)}

DEFINITIONS IMPLICIT TAGS::=

BEGIN

--EXPORTS ALL --

IMPORTS
        id-pe, id-qt, id-kp, id-ad, id-qt-unotice,
            ORAddress, Name, RelativeDistinguishedName,
            CertificateSerialNumber, CertificateList,
            AlgorithmIdentifier, ub-name, DirectoryString, Attribute,
            EXTENSION
            FROM PKIX1Explicit93 {iso(1) identified-organization(3)
            dod(6) internet(1) security(5) mechanisms(5) pkix(7)
            id-mod(0) id-pkix1-explicit-93(3)};

-- Key and policy information extensions --

authorityKeyIdentifier EXTENSION ::= {
        SYNTAX          AuthorityKeyIdentifier
        IDENTIFIED BY   id-ce-authorityKeyIdentifier }

AuthorityKeyIdentifier ::= SEQUENCE {
    keyIdentifier               [0] KeyIdentifier            OPTIONAL,
    authorityCertIssuer         [1] GeneralNames             OPTIONAL,
    authorityCertSerialNumber   [2] CertificateSerialNumber  OPTIONAL }
        ( WITH COMPONENTS       {..., authorityCertIssuer PRESENT,
                                authorityCertSerialNumber PRESENT} |
         WITH COMPONENTS        {..., authorityCertIssuer ABSENT,
                                authorityCertSerialNumber ABSENT} )

KeyIdentifier ::= OCTET STRING

subjectKeyIdentifier EXTENSION ::= {
        SYNTAX          SubjectKeyIdentifier
        IDENTIFIED BY   id-ce-subjectKeyIdentifier }

SubjectKeyIdentifier ::= KeyIdentifier

keyUsage EXTENSION ::= {
        SYNTAX  KeyUsage
        IDENTIFIED BY id-ce-keyUsage }



Housley, Ford, Polk, & Solo                                   [Page 107]


INTERNET DRAFT                                             June 16, 1998


KeyUsage ::= BIT STRING {
        digitalSignature     (0),
        nonRepudiation       (1),
        keyEncipherment      (2),
        dataEncipherment     (3),
        keyAgreement         (4),
        keyCertSign          (5),
        cRLSign              (6) }

extendedKeyUsage EXTENSION ::= {
        SYNTAX SEQUENCE SIZE (1..MAX) OF KeyPurposeId
        IDENTIFIED BY id-ce-extKeyUsage }

KeyPurposeId ::= OBJECT IDENTIFIER

-- PKIX-defined extended key purpose OIDs
id-kp-serverAuth      OBJECT IDENTIFIER ::= { id-kp 1 }
id-kp-clientAuth      OBJECT IDENTIFIER ::= { id-kp 2 }
id-kp-codeSigning     OBJECT IDENTIFIER ::= { id-kp 3 }
id-kp-emailProtection OBJECT IDENTIFIER ::= { id-kp 4 }
id-kp-ipsecEndSystem  OBJECT IDENTIFIER ::= { id-kp 5 }
id-kp-ipsecTunnel     OBJECT IDENTIFIER ::= { id-kp 6 }
id-kp-ipsecUser       OBJECT IDENTIFIER ::= { id-kp 7 }
id-kp-timeStamping    OBJECT IDENTIFIER ::= { id-kp 8 }

privateKeyUsagePeriod EXTENSION ::= {
        SYNTAX  PrivateKeyUsagePeriod
        IDENTIFIED BY { id-ce-privateKeyUsagePeriod } }

PrivateKeyUsagePeriod ::= SEQUENCE {
        notBefore       [0]     GeneralizedTime OPTIONAL,
        notAfter        [1]     GeneralizedTime OPTIONAL }
        ( WITH COMPONENTS       {..., notBefore PRESENT} |
        WITH COMPONENTS         {..., notAfter PRESENT} )

certificatePolicies EXTENSION ::= {
        SYNTAX  CertificatePoliciesSyntax
        IDENTIFIED BY id-ce-certificatePolicies }

CertificatePoliciesSyntax ::=
                SEQUENCE SIZE (1..MAX) OF PolicyInformation

PolicyInformation ::= SEQUENCE {
        policyIdentifier   CertPolicyId,
        policyQualifiers   SEQUENCE SIZE (1..MAX) OF
                PolicyQualifierInfo OPTIONAL }

CertPolicyId ::= OBJECT IDENTIFIER



Housley, Ford, Polk, & Solo                                   [Page 108]


INTERNET DRAFT                                             June 16, 1998


PolicyQualifierInfo ::= SEQUENCE {
        policyQualifierId       CERT-POLICY-QUALIFIER.&id
                                    ({SupportedPolicyQualifiers}),
        qualifier               CERT-POLICY-QUALIFIER.&Qualifier
                                    ({SupportedPolicyQualifiers}
                                    {@policyQualifierId})OPTIONAL }

SupportedPolicyQualifiers CERT-POLICY-QUALIFIER ::= { noticeToUser |
                                                      pointerToCPS }

CERT-POLICY-QUALIFIER ::= CLASS {
        &id             OBJECT IDENTIFIER UNIQUE,
        &Qualifier      OPTIONAL }
WITH SYNTAX {
        POLICY-QUALIFIER-ID     &id
        [QUALIFIER-TYPE &Qualifier] }

policyMappings EXTENSION ::= {
        SYNTAX  PolicyMappingsSyntax
        IDENTIFIED BY id-ce-policyMappings }

PolicyMappingsSyntax ::= SEQUENCE SIZE (1..MAX) OF SEQUENCE {
        issuerDomainPolicy           CertPolicyId,
        subjectDomainPolicy          CertPolicyId }

-- Certificate subject and certificate issuer attributes extensions --

subjectAltName EXTENSION ::= {
        SYNTAX  GeneralNames
        IDENTIFIED BY id-ce-subjectAltName }

GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName

GeneralName ::= CHOICE {
        otherName                   [0] INSTANCE OF OTHER-NAME,
        rfc822Name                  [1] IA5String,
        dNSName                     [2] IA5String,
        x400Address                 [3] ORAddress,
        directoryName               [4] Name,
        ediPartyName                [5] EDIPartyName,
        uniformResourceIdentifier   [6] IA5String,
        iPAddress                   [7] OCTET STRING,
        registeredID                [8] OBJECT IDENTIFIER }

OTHER-NAME ::= TYPE-IDENTIFIER

EDIPartyName ::= SEQUENCE {
        nameAssigner        [0] DirectoryString {ub-name} OPTIONAL,



Housley, Ford, Polk, & Solo                                   [Page 109]


INTERNET DRAFT                                             June 16, 1998


        partyName           [1] DirectoryString {ub-name} }

issuerAltName EXTENSION ::= {
        SYNTAX  GeneralNames
        IDENTIFIED BY id-ce-issuerAltName }

subjectDirectoryAttributes EXTENSION ::= {
        SYNTAX  AttributesSyntax
        IDENTIFIED BY id-ce-subjectDirectoryAttributes }

AttributesSyntax ::= SEQUENCE SIZE (1..MAX) OF Attribute

-- Certification path constraints extensions --

basicConstraints EXTENSION ::= {
        SYNTAX  BasicConstraintsSyntax
        IDENTIFIED BY id-ce-basicConstraints }

BasicConstraintsSyntax ::= SEQUENCE {
        cA                      BOOLEAN DEFAULT FALSE,
        pathLenConstraint       INTEGER (0..MAX) OPTIONAL }

nameConstraints EXTENSION ::= {
        SYNTAX  NameConstraintsSyntax
        IDENTIFIED BY id-ce-nameConstraints }

NameConstraintsSyntax ::= SEQUENCE {
        permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
        excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }

GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree

GeneralSubtree ::= SEQUENCE {
        base                    GeneralName,
        minimum         [0]     BaseDistance DEFAULT 0,
        maximum         [1]     BaseDistance OPTIONAL }

BaseDistance ::= INTEGER (0..MAX)

policyConstraints EXTENSION ::= {
        SYNTAX  PolicyConstraintsSyntax
        IDENTIFIED BY id-ce-policyConstraints }

PolicyConstraintsSyntax ::= SEQUENCE SIZE (1..MAX) OF SEQUENCE {
        requireExplicitPolicy   [0] SkipCerts OPTIONAL,
        inhibitPolicyMapping    [1] SkipCerts OPTIONAL }

SkipCerts ::= INTEGER (0..MAX)



Housley, Ford, Polk, & Solo                                   [Page 110]


INTERNET DRAFT                                             June 16, 1998


-- Basic CRL extensions --

cRLNumber EXTENSION ::= {
        SYNTAX  CRLNumber
        IDENTIFIED BY id-ce-cRLNumber }

CRLNumber ::= INTEGER (0..MAX)

reasonCode EXTENSION ::= {
        SYNTAX  CRLReason
        IDENTIFIED BY id-ce-reasonCode }

CRLReason ::= ENUMERATED {
        unspecified             (0),
        keyCompromise           (1),
        cACompromise            (2),
        affiliationChanged      (3),
        superseded              (4),
        cessationOfOperation    (5),
        certificateHold         (6),
        removeFromCRL           (8) }

instructionCode EXTENSION ::= {
        SYNTAX  HoldInstruction
        IDENTIFIED BY id-ce-instructionCode }

HoldInstruction ::= OBJECT IDENTIFIER

-- holdinstructions described in this specification, from ANSI x9

-- ANSI x9 arc holdinstruction arc
holdInstruction OBJECT IDENTIFIER ::= {
     joint-iso-ccitt(2) member-body(2) us(840) x9cm(10040) 2}

-- ANSI X9 holdinstructions referenced by this standard
id-holdinstruction-none OBJECT IDENTIFIER ::= {holdInstruction 1}
id-holdinstruction-callissuer OBJECT IDENTIFIER ::= {holdInstruction 2}
id-holdinstruction-reject OBJECT IDENTIFIER ::= {holdInstruction 3}

invalidityDate EXTENSION ::= {
        SYNTAX  GeneralizedTime
        IDENTIFIED BY id-ce-invalidityDate }

-- CRL distribution points and delta-CRL extensions --

cRLDistributionPoints EXTENSION ::= {
        SYNTAX  CRLDistPointsSyntax
        IDENTIFIED BY id-ce-cRLDistributionPoints }



Housley, Ford, Polk, & Solo                                   [Page 111]


INTERNET DRAFT                                             June 16, 1998


CRLDistPointsSyntax ::= SEQUENCE SIZE (1..MAX) OF DistributionPoint

DistributionPoint ::= SEQUENCE {
        distributionPoint       [0]     DistributionPointName OPTIONAL,
        reasons         [1]     ReasonFlags OPTIONAL,
        cRLIssuer               [2]     GeneralNames OPTIONAL }

DistributionPointName ::= CHOICE {
        fullName                [0]     GeneralNames,
        nameRelativeToCRLIssuer [1]     RelativeDistinguishedName }

ReasonFlags ::= BIT STRING {
        unused                  (0),
        keyCompromise           (1),
        caCompromise            (2),
        affiliationChanged      (3),
        superseded              (4),
        cessationOfOperation    (5),
        certificateHold         (6) }

issuingDistributionPoint EXTENSION ::= {
        SYNTAX  IssuingDistPointSyntax
        IDENTIFIED BY id-ce-issuingDistributionPoint }

IssuingDistPointSyntax ::= SEQUENCE {
        distributionPoint       [0] DistributionPointName OPTIONAL,
        onlyContainsUserCerts   [1] BOOLEAN DEFAULT FALSE,
        onlyContainsCACerts     [2] BOOLEAN DEFAULT FALSE,
        onlySomeReasons         [3] ReasonFlags OPTIONAL,
        indirectCRL             [4] BOOLEAN DEFAULT FALSE }

certificateIssuer EXTENSION ::= {
        SYNTAX          GeneralNames
        IDENTIFIED BY id-ce-certificateIssuer }

deltaCRLIndicator EXTENSION ::= {
        SYNTAX          BaseCRLNumber
        IDENTIFIED BY id-ce-deltaCRLIndicator }

BaseCRLNumber ::= CRLNumber

-- Object identifier assignments for ISO certificate extensions --
id-ce   OBJECT IDENTIFIER       ::=     {joint-iso-ccitt(2) ds(5) 29}

id-ce-subjectDirectoryAttributes   OBJECT IDENTIFIER ::= {id-ce 9}
id-ce-subjectKeyIdentifier         OBJECT IDENTIFIER ::= {id-ce 14}
id-ce-keyUsage                     OBJECT IDENTIFIER ::= {id-ce 15}
id-ce-privateKeyUsagePeriod        OBJECT IDENTIFIER ::= {id-ce 16}



Housley, Ford, Polk, & Solo                                   [Page 112]


INTERNET DRAFT                                             June 16, 1998


id-ce-subjectAltName               OBJECT IDENTIFIER ::= {id-ce 17}
id-ce-issuerAltName                OBJECT IDENTIFIER ::= {id-ce 18}
id-ce-basicConstraints             OBJECT IDENTIFIER ::= {id-ce 19}
id-ce-cRLNumber                    OBJECT IDENTIFIER ::= {id-ce 20}
id-ce-reasonCode                   OBJECT IDENTIFIER ::= {id-ce 21}
id-ce-instructionCode              OBJECT IDENTIFIER ::= {id-ce 23}
id-ce-invalidityDate               OBJECT IDENTIFIER ::= {id-ce 24}
id-ce-deltaCRLIndicator            OBJECT IDENTIFIER ::= {id-ce 27}
id-ce-issuingDistributionPoint     OBJECT IDENTIFIER ::= {id-ce 28}
id-ce-certificateIssuer            OBJECT IDENTIFIER ::= {id-ce 29}
id-ce-nameConstraints              OBJECT IDENTIFIER ::= {id-ce 30}
id-ce-cRLDistributionPoints        OBJECT IDENTIFIER ::= {id-ce 31}
id-ce-certificatePolicies          OBJECT IDENTIFIER ::= {id-ce 32}
id-ce-policyMappings               OBJECT IDENTIFIER ::= {id-ce 33}
id-ce-policyConstraints            OBJECT IDENTIFIER ::= {id-ce 36}
id-ce-authorityKeyIdentifier       OBJECT IDENTIFIER ::= {id-ce 35}
id-ce-extKeyUsage                  OBJECT IDENTIFIER ::= {id-ce 37}

-- PKIX 1 extensions

authorityInfoAccess EXTENSION ::= {
        SYNTAX  AuthorityInfoAccessSyntax
        IDENTIFIED BY id-pe-authorityInfoAccess }

AuthorityInfoAccessSyntax  ::=
        SEQUENCE SIZE (1..MAX) OF AccessDescription

AccessDescription  ::=  SEQUENCE {
        accessMethod          OBJECT IDENTIFIER,
        accessLocation        GeneralName  }

id-pe-authorityInfoAccess OBJECT IDENTIFIER ::= { id-pe 1 }

id-ad-caIssuers OBJECT IDENTIFIER ::= { id-ad 2 }

-- PKIX policy qualifier definitions

noticeToUser CERT-POLICY-QUALIFIER ::= {
     POLICY-QUALIFIER-ID    id-qt-cps QUALIFIER-TYPE       CPSuri}

pointerToCPS CERT-POLICY-QUALIFIER ::= {
     POLICY-QUALIFIER-ID    id-qt-unotice QUALIFIER-TYPE   UserNotice}

id-qt-cps      OBJECT IDENTIFIER ::=  { id-qt 1 }
id-qt-unotice  OBJECT IDENTIFIER ::=  { id-qt 2 }

CPSuri ::= IA5String




Housley, Ford, Polk, & Solo                                   [Page 113]


INTERNET DRAFT                                             June 16, 1998


UserNotice ::= SEQUENCE {
     noticeRef        NoticeReference OPTIONAL,
     explicitText     DisplayText OPTIONAL}

NoticeReference ::= SEQUENCE {
     organization     DisplayText,
     noticeNumbers    SEQUENCE OF INTEGER }

DisplayText ::= CHOICE {
     visibleString    VisibleString  (SIZE (1..200)),
     bmpString        BMPString      (SIZE (1..200)),
     utf8String       UTF8String     (SIZE (1..200)) }


END



Appendix C. ASN.1 Notes

   The construct "SEQUENCE SIZE (1..MAX) OF" appears in several ASN.1
   constructs. A valid ASN.1 sequence will have zero or more entries.
   The SIZE (1..MAX) construct constrains the sequence to have at least
   one entry. MAX indicates the upper bound is unspecified. Implementa-
   tions are free to choose an upper bound that suits their environment.

   The construct "positiveInt ::= INTEGER (0..MAX)" defines positiveInt
   as a subtype of INTEGER containing integers greater than or equal to
   zero.  The upper bound is unspecified. Implementations are free to
   select an upper bound that suits their environment.

   The character string type PrintableString supports a very basic Latin
   character set:  the lower case letters 'a' through 'z', upper case
   letters 'A' through 'Z', the digits '0' through '9', eleven special
   characters ' " ( ) + , - . / : ? and space.

   The character string type TeletexString is a superset of Printable-
   String.  TeletexString supports a fairly standard (ascii-like) Latin
   character set, Latin characters with non-spacing accents and Japanese
   characters.

   The character string type UniversalString supports any of the charac-
   ters allowed by ISO 10646-1. ISO 10646 is the Universal multiple-
   octet coded Character Set (UCS).  ISO 10646-1 specifes the architec-
   ture and the "basic multilingual plane" - a large standard character
   set which includes all major world character standards.

   The character string type UTF8String will be introduced in the 1998



Housley, Ford, Polk, & Solo                                   [Page 114]


INTERNET DRAFT                                             June 16, 1998


   version of ASN.1.  UTF8String is a universal type and has been
   assigned tag number 12.  The content of UTF8String was defined by RFC
   2044 and updated in RFC 2279, "UTF-8, a transformation Format of ISP
   10646."  ISO is expected to formally add UTF8String to the list of
   choices for DirectoryString in 1998 as well.

   In anticipation of these changes, and in conformance with IETF Best
   Practices codified in RFC 2277, IETF Policy on Character Sets and
   Languages, this document includes UTF8String as a choice in Directo-
   ryString and the CPS qualifier extensions.

Appendix D. Examples

   This section contains four examples: three certificates and a CRL.
   The first two certificates and the CRL comprise a minimal certifica-
   tion path.

   Section D.1 contains two annotated hex dumps of a "self-signed" cer-
   tificate issued by a CA whose distinguished name is
   cn=us,o=gov,ou=nist.  The certificate contains a DSA public key with
   parameters, and is signed by the corresponding DSA private key. The
   first hex dump is a basic dump of the ASN.1 encoding and does not not
   reflect the fact that the object is a certificate. The second dump
   identfies the values of the various certificate fields.

   Section D.2 contains  an annotated hex dump of an end-entity certifi-
   cate.  The end entity certificate contains a DSA public key, and is
   signed by the private key corresponding to the "self-signed" certifi-
   cate in section D.1.   The first hex dump is a basic dump of the
   ASN.1 encoding and does not not reflect the fact that the object is a
   certificate. The second dump identfies the values of the various cer-
   tificate fields.

   Section D.3 contains a dump of an end entity certificate which con-
   tains an RSA public key and is signed with RSA and MD5.  This certi-
   ficate is not part of the minimal certification path.

   Section D.4 contains an annotated hex dump of a CRL.  The CRL is
   issued by the CA whose distinguished name is cn=us,o=gov,ou=nist and
   the list of revoked certifcates includes the end entity certificate
   presented in D.2.  The hex dump is a basic dump of the ASN.1 encod-
   ing.

D.1 Certificate

   This section contains an annotated hex dump of a 662 byte version 3
   certificate.  The certificate contains the following information:
   (a) the serial number is 17 (11 hex);



Housley, Ford, Polk, & Solo                                   [Page 115]


INTERNET DRAFT                                             June 16, 1998


   (b) the certificate is signed with DSA and the SHA-1 hash algorithm;
   (c) the issuer's distinguished name is OU=nist;O=gov;C=US
   (d) and the subject's distinguished name is OU=nist;O=gov;C=US
   (e) the certificate was issued on June 30, 1997 and will expire on
   December 31, 1997;
   (f) the certificate contains a 1024 bit DSA public key with parame-
   ters; and
   (g) the certificate is a CA certificate (as indicated through the
   basic constraints extension.)

D.1.1 ASN.1 Dump of "Self-Signed" Certificate

0000 30 82 02 92  658: SEQUENCE
0004 30 82 02 52  594: . SEQUENCE
0008 a0 03          3: . . [0]
0010 02 01          1: . . . INTEGER 2
0013 02 01          1: . . INTEGER 17
0016 30 09          9: . . SEQUENCE
0018 06 07          7: . . . OID 1.2.840.10040.4.3: dsa-with-sha
0027 30 2a         42: . . SEQUENCE
0029 31 0b         11: . . . SET
0031 30 09          9: . . . . SEQUENCE
0033 06 03          3: . . . . . OID 2.5.4.6: C
0038 13 02          2: . . . . . PrintableString  'US'
0042 31 0c         12: . . . SET
0044 30 0a         10: . . . . SEQUENCE
0046 06 03          3: . . . . . OID 2.5.4.10: O
0051 13 03          3: . . . . . PrintableString  'gov'
0056 31 0d         13: . . . SET
0058 30 0b         11: . . . . SEQUENCE
0060 06 03          3: . . . . . OID 2.5.4.11: OU
0065 13 04          4: . . . . . PrintableString  'nist'
0071 30 1e         30: . . SEQUENCE
0073 17 0d         13: . . . UTCTime  '970630000000Z'
0088 17 0d         13: . . . UTCTime  '971231000000Z'
0103 30 2a         42: . . SEQUENCE
0105 31 0b         11: . . . SET
0107 30 09          9: . . . . SEQUENCE
0109 06 03          3: . . . . . OID 2.5.4.6: C
0114 13 02          2: . . . . . PrintableString  'US'
0118 31 0c         12: . . . SET
0120 30 0a         10: . . . . SEQUENCE
0122 06 03          3: . . . . . OID 2.5.4.10: O
0127 13 03          3: . . . . . PrintableString  'gov'
0132 31 0d         13: . . . SET
0134 30 0b         11: . . . . SEQUENCE
0136 06 03          3: . . . . . OID 2.5.4.11: OU
0141 13 04          4: . . . . . PrintableString  'nist'



Housley, Ford, Polk, & Solo                                   [Page 116]


INTERNET DRAFT                                             June 16, 1998


0147 30 82 01 b4  436: . . SEQUENCE
0151 30 82 01 29  297: . . . SEQUENCE
0155 06 07          7: . . . . OID 1.2.840.10040.4.1: dsa
0164 30 82 01 1c  284: . . . . SEQUENCE
0168 02 81 80     128: . . . . . INTEGER
                     : d4 38 02 c5 35 7b d5 0b a1 7e 5d 72 59 63 55 d3
                     : 45 56 ea e2 25 1a 6b c5 a4 ab aa 0b d4 62 b4 d2
                     : 21 b1 95 a2 c6 01 c9 c3 fa 01 6f 79 86 83 3d 03
                     : 61 e1 f1 92 ac bc 03 4e 89 a3 c9 53 4a f7 e2 a6
                     : 48 cf 42 1e 21 b1 5c 2b 3a 7f ba be 6b 5a f7 0a
                     : 26 d8 8e 1b eb ec bf 1e 5a 3f 45 c0 bd 31 23 be
                     : 69 71 a7 c2 90 fe a5 d6 80 b5 24 dc 44 9c eb 4d
                     : f9 da f0 c8 e8 a2 4c 99 07 5c 8e 35 2b 7d 57 8d
0299 02 14         20: . . . . . INTEGER
                     : a7 83 9b f3 bd 2c 20 07 fc 4c e7 e8 9f f3 39 83
                     : 51 0d dc dd
0321 02 81 80     128: . . . . . INTEGER
                     : 0e 3b 46 31 8a 0a 58 86 40 84 e3 a1 22 0d 88 ca
                     : 90 88 57 64 9f 01 21 e0 15 05 94 24 82 e2 10 90
                     : d9 e1 4e 10 5c e7 54 6b d4 0c 2b 1b 59 0a a0 b5
                     : a1 7d b5 07 e3 65 7c ea 90 d8 8e 30 42 e4 85 bb
                     : ac fa 4e 76 4b 78 0e df 6c e5 a6 e1 bd 59 77 7d
                     : a6 97 59 c5 29 a7 b3 3f 95 3e 9d f1 59 2d f7 42
                     : 87 62 3f f1 b8 6f c7 3d 4b b8 8d 74 c4 ca 44 90
                     : cf 67 db de 14 60 97 4a d1 f7 6d 9e 09 94 c4 0d
0452 03 81 84     132: . . . BIT STRING  (0 unused bits)
                     : 02 81 80 aa 98 ea 13 94 a2 db f1 5b 7f 98 2f 78
                     : e7 d8 e3 b9 71 86 f6 80 2f 40 39 c3 da 3b 4b 13
                     : 46 26 ee 0d 56 c5 a3 3a 39 b7 7d 33 c2 6b 5c 77
                     : 92 f2 55 65 90 39 cd 1a 3c 86 e1 32 eb 25 bc 91
                     : c4 ff 80 4f 36 61 bd cc e2 61 04 e0 7e 60 13 ca
                     : c0 9c dd e0 ea 41 de 33 c1 f1 44 a9 bc 71 de cf
                     : 59 d4 6e da 44 99 3c 21 64 e4 78 54 9d d0 7b ba
                     : 4e f5 18 4d 5e 39 30 bf e0 d1 f6 f4 83 25 4f 14
                     : aa 71 e1
0587 a3 0d         13: . . [3]
0589 30 0b         11: . . . SEQUENCE
0591 30 09          9: . . . . SEQUENCE
0593 06 03          3: . . . . . OID 2.5.29.19: basicConstraints
0598 04 02          2: . . . . . OCTET STRING
                     : 30 00
0602 30 09          9: . SEQUENCE
0604 06 07          7: . . OID 1.2.840.10040.4.3: dsa-with-sha
0613 03 2f         47: . BIT STRING  (0 unused bits)
                     : 30 2c 02 14 a0 66 c1 76 33 99 13 51 8d 93 64 2f
                     : ca 13 73 de 79 1a 7d 33 02 14 5d 90 f6 ce 92 4a
                     : bf 29 11 24 80 28 a6 5a 8e 73 b6 76 02 68




Housley, Ford, Polk, & Solo                                   [Page 117]


INTERNET DRAFT                                             June 16, 1998


D.1.2 Pretty Print of "Self-Signed" Certificate

      Version: v3
Serial Number: 17
Signature Alg: dsa-with-sha (1.2.840.10040.4.3)
       Issuer: C=US, O=gov, OU=nist
     Validity: from 970630000000Z
                 to 971231000000Z
      Subject: OU=nist, O=gov, C=US
SubjectPKInfo: dsa (1.2.840.10040.4.1)
       params:
        02 81 80 d4 38 02 c5 35 7b d5 0b a1 7e 5d 72 59
        63 55 d3 45 56 ea e2 25 1a 6b c5 a4 ab aa 0b d4
        62 b4 d2 21 b1 95 a2 c6 01 c9 c3 fa 01 6f 79 86
        83 3d 03 61 e1 f1 92 ac bc 03 4e 89 a3 c9 53 4a
        f7 e2 a6 48 cf 42 1e 21 b1 5c 2b 3a 7f ba be 6b
        5a f7 0a 26 d8 8e 1b eb ec bf 1e 5a 3f 45 c0 bd
        31 23 be 69 71 a7 c2 90 fe a5 d6 80 b5 24 dc 44
        9c eb 4d f9 da f0 c8 e8 a2 4c 99 07 5c 8e 35 2b
        7d 57 8d 02 14 a7 83 9b f3 bd 2c 20 07 fc 4c e7
        e8 9f f3 39 83 51 0d dc dd 02 81 80 0e 3b 46 31
        8a 0a 58 86 40 84 e3 a1 22 0d 88 ca 90 88 57 64
        9f 01 21 e0 15 05 94 24 82 e2 10 90 d9 e1 4e 10
        5c e7 54 6b d4 0c 2b 1b 59 0a a0 b5 a1 7d b5 07
        e3 65 7c ea 90 d8 8e 30 42 e4 85 bb ac fa 4e 76
        4b 78 0e df 6c e5 a6 e1 bd 59 77 7d a6 97 59 c5
        29 a7 b3 3f 95 3e 9d f1 59 2d f7 42 87 62 3f f1
        b8 6f c7 3d 4b b8 8d 74 c4 ca 44 90 cf 67 db de
        14 60 97 4a d1 f7 6d 9e 09 94 c4 0d
   Public Key:
        00 02 81 80 aa 98 ea 13 94 a2 db f1 5b 7f 98 2f
        78 e7 d8 e3 b9 71 86 f6 80 2f 40 39 c3 da 3b 4b
        13 46 26 ee 0d 56 c5 a3 3a 39 b7 7d 33 c2 6b 5c
        77 92 f2 55 65 90 39 cd 1a 3c 86 e1 32 eb 25 bc
        91 c4 ff 80 4f 36 61 bd cc e2 61 04 e0 7e 60 13
        ca c0 9c dd e0 ea 41 de 33 c1 f1 44 a9 bc 71 de
        cf 59 d4 6e da 44 99 3c 21 64 e4 78 54 9d d0 7b
        ba 4e f5 18 4d 5e 39 30 bf e0 d1 f6 f4 83 25 4f
        14 aa 71 e1
    issuerUID:
   subjectUID:
 1 extensions:
     Exten  1:   basicConstraints (2.5.29.19)
        30 00
Signature Alg: dsa-with-sha (1.2.840.10040.4.3)
    Sig Value: 368 bits:
        30 2c 02 14 a0 66 c1 76 33 99 13 51 8d 93 64 2f
        ca 13 73 de 79 1a 7d 33 02 14 5d 90 f6 ce 92 4a



Housley, Ford, Polk, & Solo                                   [Page 118]


INTERNET DRAFT                                             June 16, 1998


        bf 29 11 24 80 28 a6 5a 8e 73 b6 76 02 68

D.2 Certificate

   This section contains an annotated hex dump of a 697 byte version 3
   certificate.  The certificate contains the following information:
   (a) the serial number is 18 (12 hex);
   (b) the certificate is signed with DSA and the SHA-1 hash algorithm;
   (c) the issuer's distinguished name is OU=nist;O=gov;C=US
   (d) and the subject's distinguished name is CN=Tim
   Polk;OU=nist;O=gov;C=US
   (e) the certificate was valid from July 30, 1997 through December 1,
   1997;
   (f) the certificate contains a 1024 bit DSA public key;
   (g) the certificate is an end entity certificate, as the basic con-
   straints extension is not present;
   (h) the certificate includes one alternative name - an RFC 822
   address.


D.2.1 Basic ASN.1 Dump of "End Entity" Certificate

----------

0000 30 82 02 b5  693: SEQUENCE
0004 30 82 02 75  629: . SEQUENCE
0008 a0 03          3: . . [0]
0010 02 01          1: . . . INTEGER 2
0013 02 01          1: . . INTEGER 18
0016 30 09          9: . . SEQUENCE
0018 06 07          7: . . . OID 1.2.840.10040.4.3: dsa-with-sha
0027 30 2a         42: . . SEQUENCE
0029 31 0b         11: . . . SET
0031 30 09          9: . . . . SEQUENCE
0033 06 03          3: . . . . . OID 2.5.4.6: C
0038 13 02          2: . . . . . PrintableString  'US'
0042 31 0c         12: . . . SET
0044 30 0a         10: . . . . SEQUENCE
0046 06 03          3: . . . . . OID 2.5.4.10: O
0051 13 03          3: . . . . . PrintableString  'gov'
0056 31 0d         13: . . . SET
0058 30 0b         11: . . . . SEQUENCE
0060 06 03          3: . . . . . OID 2.5.4.11: OU
0065 13 04          4: . . . . . PrintableString  'nist'
0071 30 1e         30: . . SEQUENCE
0073 17 0d         13: . . . UTCTime  '970730000000Z'
0088 17 0d         13: . . . UTCTime  '971201000000Z'
0103 30 3d         61: . . SEQUENCE



Housley, Ford, Polk, & Solo                                   [Page 119]


INTERNET DRAFT                                             June 16, 1998


0105 31 0b         11: . . . SET
0107 30 09          9: . . . . SEQUENCE
0109 06 03          3: . . . . . OID 2.5.4.6: C
0114 13 02          2: . . . . . PrintableString  'US'
0118 31 0c         12: . . . SET
0120 30 0a         10: . . . . SEQUENCE
0122 06 03          3: . . . . . OID 2.5.4.10: O
0127 13 03          3: . . . . . PrintableString  'gov'
0132 31 0d         13: . . . SET
0134 30 0b         11: . . . . SEQUENCE
0136 06 03          3: . . . . . OID 2.5.4.11: OU
0141 13 04          4: . . . . . PrintableString  'nist'
0147 31 11         17: . . . SET
0149 30 0f         15: . . . . SEQUENCE
0151 06 03          3: . . . . . OID 2.5.4.3: CN
0156 13 08          8: . . . . . PrintableString  'Tim Polk'
0166 30 82 01 b4  436: . . SEQUENCE
0170 30 82 01 29  297: . . . SEQUENCE
0174 06 07          7: . . . . OID 1.2.840.10040.4.1: dsa
0183 30 82 01 1c  284: . . . . SEQUENCE
0187 02 81 80     128: . . . . . INTEGER
                     : d4 38 02 c5 35 7b d5 0b a1 7e 5d 72 59 63 55 d3
                     : 45 56 ea e2 25 1a 6b c5 a4 ab aa 0b d4 62 b4 d2
                     : 21 b1 95 a2 c6 01 c9 c3 fa 01 6f 79 86 83 3d 03
                     : 61 e1 f1 92 ac bc 03 4e 89 a3 c9 53 4a f7 e2 a6
                     : 48 cf 42 1e 21 b1 5c 2b 3a 7f ba be 6b 5a f7 0a
                     : 26 d8 8e 1b eb ec bf 1e 5a 3f 45 c0 bd 31 23 be
                     : 69 71 a7 c2 90 fe a5 d6 80 b5 24 dc 44 9c eb 4d
                     : f9 da f0 c8 e8 a2 4c 99 07 5c 8e 35 2b 7d 57 8d
0318 02 14         20: . . . . . INTEGER
                     : a7 83 9b f3 bd 2c 20 07 fc 4c e7 e8 9f f3 39 83
                     : 51 0d dc dd
0340 02 81 80     128: . . . . . INTEGER
                     : 0e 3b 46 31 8a 0a 58 86 40 84 e3 a1 22 0d 88 ca
                     : 90 88 57 64 9f 01 21 e0 15 05 94 24 82 e2 10 90
                     : d9 e1 4e 10 5c e7 54 6b d4 0c 2b 1b 59 0a a0 b5
                     : a1 7d b5 07 e3 65 7c ea 90 d8 8e 30 42 e4 85 bb
                     : ac fa 4e 76 4b 78 0e df 6c e5 a6 e1 bd 59 77 7d
                     : a6 97 59 c5 29 a7 b3 3f 95 3e 9d f1 59 2d f7 42
                     : 87 62 3f f1 b8 6f c7 3d 4b b8 8d 74 c4 ca 44 90
                     : cf 67 db de 14 60 97 4a d1 f7 6d 9e 09 94 c4 0d
0471 03 81 84     132: . . . BIT STRING  (0 unused bits)
                     : 02 81 80 a8 63 b1 60 70 94 7e 0b 86 08 93 0c 0d
                     : 08 12 4a 58 a9 af 9a 09 38 54 3b 46 82 fb 85 0d
                     : 18 8b 2a 77 f7 58 e8 f0 1d d2 18 df fe e7 e9 35
                     : c8 a6 1a db 8d 3d 3d f8 73 14 a9 0b 39 c7 95 f6
                     : 52 7d 2d 13 8c ae 03 29 3c 4e 8c b0 26 18 b6 d8
                     : 11 1f d4 12 0c 13 ce 3f f1 c7 05 4e df e1 fc 44



Housley, Ford, Polk, & Solo                                   [Page 120]


INTERNET DRAFT                                             June 16, 1998


                     : fd 25 34 19 4a 81 0d dd 98 42 ac d3 b6 91 0c 7f
                     : 16 72 a3 a0 8a d7 01 7f fb 9c 93 e8 99 92 c8 42
                     : 47 c6 43
0606 a3 1d         29: . . [3]
0608 30 1b         27: . . . SEQUENCE
0610 30 19         25: . . . . SEQUENCE
0612 06 03          3: . . . . . OID 2.5.29.17: subjectAltName
0617 04 12         18: . . . . . OCTET STRING
                     : 30 10 81 0e 77 70 6f 6c 6b 40 6e 69 73 74 2e 67
                     : 6f 76
0637 30 09          9: . SEQUENCE
0639 06 07          7: . . OID 1.2.840.10040.4.3: dsa-with-sha
0648 03 2f         47: . BIT STRING  (0 unused bits)
                     : 30 2c 02 14 3c 02 e0 ab d9 5d 05 77 75 15 71 58
                     : 92 29 48 c4 1c 54 df fc 02 14 5b da 53 98 7f c5
                     : 33 df c6 09 b2 7a e3 6f 97 70 1e 14 ed 94

D.2.2 Pretty Print of "End Entity" Certificate

      Version: v3
Serial Number: 18
Signature Alg: dsa-with-sha (1.2.840.10040.4.3)
       Issuer: C=US, O=gov, OU=nist
     Validity: from 970730000000Z
                 to 971201000000Z
      Subject: CN=Tim Polk, OU=nist, O=gov, C=US
SubjectPKInfo: dsa (1.2.840.10040.4.1)
       params:
        02 81 80 d4 38 02 c5 35 7b d5 0b a1 7e 5d 72 59
        63 55 d3 45 56 ea e2 25 1a 6b c5 a4 ab aa 0b d4
        62 b4 d2 21 b1 95 a2 c6 01 c9 c3 fa 01 6f 79 86
        83 3d 03 61 e1 f1 92 ac bc 03 4e 89 a3 c9 53 4a
        f7 e2 a6 48 cf 42 1e 21 b1 5c 2b 3a 7f ba be 6b
        5a f7 0a 26 d8 8e 1b eb ec bf 1e 5a 3f 45 c0 bd
        31 23 be 69 71 a7 c2 90 fe a5 d6 80 b5 24 dc 44
        9c eb 4d f9 da f0 c8 e8 a2 4c 99 07 5c 8e 35 2b
        7d 57 8d 02 14 a7 83 9b f3 bd 2c 20 07 fc 4c e7
        e8 9f f3 39 83 51 0d dc dd 02 81 80 0e 3b 46 31
        8a 0a 58 86 40 84 e3 a1 22 0d 88 ca 90 88 57 64
        9f 01 21 e0 15 05 94 24 82 e2 10 90 d9 e1 4e 10
        5c e7 54 6b d4 0c 2b 1b 59 0a a0 b5 a1 7d b5 07
        e3 65 7c ea 90 d8 8e 30 42 e4 85 bb ac fa 4e 76
        4b 78 0e df 6c e5 a6 e1 bd 59 77 7d a6 97 59 c5
        29 a7 b3 3f 95 3e 9d f1 59 2d f7 42 87 62 3f f1
        b8 6f c7 3d 4b b8 8d 74 c4 ca 44 90 cf 67 db de
        14 60 97 4a d1 f7 6d 9e 09 94 c4 0d
   Public Key:
        00 02 81 80 a8 63 b1 60 70 94 7e 0b 86 08 93 0c



Housley, Ford, Polk, & Solo                                   [Page 121]


INTERNET DRAFT                                             June 16, 1998


        0d 08 12 4a 58 a9 af 9a 09 38 54 3b 46 82 fb 85
        0d 18 8b 2a 77 f7 58 e8 f0 1d d2 18 df fe e7 e9
        35 c8 a6 1a db 8d 3d 3d f8 73 14 a9 0b 39 c7 95
        f6 52 7d 2d 13 8c ae 03 29 3c 4e 8c b0 26 18 b6
        d8 11 1f d4 12 0c 13 ce 3f f1 c7 05 4e df e1 fc
        44 fd 25 34 19 4a 81 0d dd 98 42 ac d3 b6 91 0c
        7f 16 72 a3 a0 8a d7 01 7f fb 9c 93 e8 99 92 c8
        42 47 c6 43
    issuerUID:
   subjectUID:
 1 extensions:
     Exten  1:   subjectAltName (2.5.29.17)
        30 10 81 0e 77 70 6f 6c 6b 40 6e 69 73 74 2e 67
        6f 76
Signature Alg: dsa-with-sha (1.2.840.10040.4.3)
    Sig Value: 368 bits:
        30 2c 02 14 3c 02 e0 ab d9 5d 05 77 75 15 71 58
        92 29 48 c4 1c 54 df fc 02 14 5b da 53 98 7f c5
        33 df c6 09 b2 7a e3 6f 97 70 1e 14 ed 94

D.3 End-Entity Certificate Using RSA

   This section contains an annotated hex dump of a 675 byte version 3
   certificate.  The certificate contains the following information:
   (a) the serial number is 2;
   (b) the certificate is signed with RSA and the MD5 hash algorithm;
   (c) the issuer's distinguished name is OU=esCert-
   UPC;O=UPC;L=Barcelona;STREET=Catalunya;C=ES
   (d) and the subject's distinguished name is
   CN=escert.upc.es;OU=esCert-
   UPC;O=UPC;L=Barcelona;STREET=Catalunya;C=ES
   (e) the certificate was issued on May 21, 1996 and expired on May 21,
   1997;
   (f) the certificate contains a 768 bit RSA public key which is
   intended for generation of digital signatures;
   (g) the certificate is an end entity certificate (not a CA certifi-
   cate);
   (h) the certificate includes two alternative names - an RFC 822
   address, and a URL.

 sequence length 029f=671 bytes
 30 82 02 9f
    sequence length 0208h=520 bytes
    30 82 02 08
       explicit tag 00 "Version"
       a0 03
          integer length 1 value 2 [version is 3]
          02 01 02



Housley, Ford, Polk, & Solo                                   [Page 122]


INTERNET DRAFT                                             June 16, 1998


       integer length 1 value 2 [serial number 2]
       02 01 02
       sequence length 13 [signature]
       30 0d
          object identifier length 9 {1 2 840 113549 1 1 4}
                                {iso(1) member-body(2) us(840) etc.}
          06 09 2a 86 48 86 f7 0d 01 01 04
          null [null parameters]
          05 00
       sequence length 88 [issuer]
          30 58
             RDN length 11
             31 0b
                sequence length 9
                30 09
                   object identifier length 3  { 2 5 4 6 }
                   06 03 55 04 06
                   printable string length 2 "ES"
                   13 02 45 53
             RDN length 18
             31 12
                sequence length 16
                30 10
                   object identifier length 3 { 2 5 4 9 }
                   06 03 55 04 09
                   printable string length 9 "Catalunya"
                   13 09 43 61 74 61 6c 75 6e 79 61
             RDN length 18
             31 12
                sequence length 16
                30 10
                   object identifier length 3 { 2 5 4 7 }
                   06 03 55 04 07
                   printable string length 9 "Barcelona"
                   13 09 42 61 72 63 65 6c 6f 6e 61
             RDN length 12
             31 0c
                sequence length 10
                30 0a
                   object identifier {2 5 4 10 }
                   06 03 55 04 0a
                   printable string length 3 "UPC"
                   13 03 55 50 43
             RDN length 19
             31 13
                sequence length 17
                30 11
                   object identifier {2 5 4 13 }



Housley, Ford, Polk, & Solo                                   [Page 123]


INTERNET DRAFT                                             June 16, 1998


                   06 03 55 04 0b
                   printable string length 10 "esCERT-UPC"
                   13 0a 65 73 43 45 52 54 2d 55 50 43
       sequence length 0x1e= 30
          30 1e
             UTCTime "960521095826Z"
             17 0d 39 36 30 35 32 31 30 39 35 38 32 36 5a
             UTCTime "979521095826Z"
             17 0d 39 37 30 35 32 31 30 39 35 38 32 36 5a
       sequence length
       30 70
          31 0b
             30 09
                { 2 5 4 6 }
                06 03 55 04 06
                "ES"
                13 02 45 53
          RDN
          31 12
             30 10
                { 2 5 4 9 }
                06 03 55 04 09
                "Catalunya"
                13 09 43 61 74 61 6c 75 6e 7961
          RDN
          31 12
             30 10
                { 2 5 4 7 }
                06 03 55 04 07
                "Barcelona"
                13 09 42 61 72 63 65 6c 6f 6e 61
          RDN
          31 0c
             30 0a
                { 2 5 4 10 }
                06 03 55 04 0a
                "UPC"
                13 03 55 50 43
          RDN
          31 13
             30 11
                { 2 5 4 11 }
                06 03 55 04 0b
                "esCERT-UPC"
                13 0a 65 73 43 45 52 54 2d 55 50 43
          RDN
          31 16
             30 14



Housley, Ford, Polk, & Solo                                   [Page 124]


INTERNET DRAFT                                             June 16, 1998


                { 2 5 4 3 }
                06 03 55 04 03
                "escert.upc.es"
                13 0d 65 73 63 65 72 74 2e 75 70 63 2e 65 73
        subjectPublicKeyInfo
          30 7c
             algorithmIdentifier
             30 0d
                { 1 2 840 113549 1 1 1}
                06 09 2a 86 48 86 f7 0d 01 01 01
                null parameters
                05 00
             { subject's public key }
             03 6b  BIT STRING length 107 bytes (856 bits)
                               0030 6802 6100 beaa 8b77 54a3 afca 779f
                               2fb0 cf43 88ff a66d 7955 5b61 8c68 ec48
                               1e8a 8638 a4fe 19b8 6217 1d9d 0f47 2cff
                               638f 2991 04d1 52bc 7f67 b6b2 8f74 55c1
                               3321 6c8f ab01 9524 c8b2 7393 9d22 6150
                               a935 fb9d 5750 32ef 5652 5093 abb1 8894
                               7856 15c6 1c8b 0203 0100 01
         explicit tag 3 "extensions" length 0x84=132
         a3 81 84
            sequence 129 bytes
            30 81 81
               sequence 12 bytes
               30 0b
                  id-ce-keyUsage = { 2 5 29 15 }
                  06 03 55 1d 0f
                  by default, critical = FALSE
                  octet string
                  04 04 03 02 07 80
               30 09
                  id-ce-basicConstraints = { 2 5 29 19 }
                  06 03 55 1d 13
                  by default, critical = FALSE
                  octet string
                  04 02
                     null sequence - by default, subject is end entity
                     30 00
               30 3d
                  id-ce-subjectAltName = { 2 5 29 17 }
                  06 03 55 1d 11
                  by default, critical = FALSE
                  octet string
                  04 36
                     30 34
                        rfc822name



Housley, Ford, Polk, & Solo                                   [Page 125]


INTERNET DRAFT                                             June 16, 1998


                        a1 1a
                           IA5String "escert-upc@escert.upc.es"
                           16 18 65 73 63 65 72 74 2d 75 70 63 40 65 73
                           63 65 72 74 2e 75 70 63 2e 65 73
                        uniformResourceIdentifier
                        a6 16
                           IA5String "http://escert.upc.es"
                           16 14 68 74 74 70 3a 2f 2f 65 73 63 65 72 74
                           2e 75 70 63 2e 65 73
               30 28
                  id-ce-certificatePolicies = { 2 5 29 32 }
                  06 03 55 1d 20
                  by default, critical = FALSE
                  octet string
                  04 21
                     30 1f
                        30 1d
                           06 04 2a 84 80 00
                           { 2 2 32768 }
                     30 15
                        30 07
                           { 2 2 32768 1 }
                           06 05 2a 84 80 00 01
                         30 0a
                            { 2 2 32768 2 }
                            06 05 2a 84 80 00 02
                            02 01 0a
   sequence
   30 0d
      { 1 2 840 113549 1 1 4 }
      06 09 2a 86 48 86 f7 0d 01 01 04
      null parameters
      05 00
   bit string length 129  (signature)
   03 81 81 005b fdc2 a704 d483 4e17 6da6 fa27 e7c6
            f8ab b95d 9fd0 a1df d797 9fe0 20a6 c57a
            64cd 522f e9ae dabe 9ce4 d597 edf1 84c0
            d0fe 9bef 54b1 80e5 bf3c c9ed 9320 2d52
            21e9 bcb9 e34f ac11 650e 8fa1 6899 6347
            e53d e442 7313 fac5 c834 8cc0 4118 89d5
            e6a0 185b 5d86 1c1e c670 d80e 8964 9483
            8e3b 407c 59cf 2b2f b7ce 9798 1215 ef13
            d4








Housley, Ford, Polk, & Solo                                   [Page 126]


INTERNET DRAFT                                             June 16, 1998


D.4 Certificate Revocation List

   This section contains an annotated hex dump of a version 2 CRL with
   one extension (cRLNumber). The CRL was issued by OU=nist;O=gov;C=us
   on July 7, 1996; the next scheduled issuance was August 7, 1996.  The
   CRL includes one revoked certificates: serial number 18 (12 hex).
   The CRL itself is number 18, and it was signed with DSA and SHA-1.

0000 30 81 ba     186: SEQUENCE
0003 30 7c        124: . SEQUENCE
0005 02 01          1: . . INTEGER 1
0008 30 09          9: . . SEQUENCE
0010 06 07          7: . . . OID 1.2.840.10040.4.3: dsa-with-sha
0019 30 2a         42: . . SEQUENCE
0021 31 0b         11: . . . SET
0023 30 09          9: . . . . SEQUENCE
0025 06 03          3: . . . . . OID 2.5.4.6: C
0030 13 02          2: . . . . . PrintableString  'US'
0034 31 0c         12: . . . SET
0036 30 0a         10: . . . . SEQUENCE
0038 06 03          3: . . . . . OID 2.5.4.10: O
0043 13 03          3: . . . . . PrintableString  'gov'
0048 31 0d         13: . . . SET
0050 30 0b         11: . . . . SEQUENCE
0052 06 03          3: . . . . . OID 2.5.4.11: OU
0057 13 04          4: . . . . . PrintableString  'nist'
0063 17 0d         13: . . UTCTime  '970801000000Z'
0078 17 0d         13: . . UTCTime  '970808000000Z'
0093 30 22         34: . . SEQUENCE
0095 30 20         32: . . . SEQUENCE
0097 02 01          1: . . . . INTEGER 18
0100 17 0d         13: . . . . UTCTime  '970731000000Z'
0115 30 0c         12: . . . . SEQUENCE
0117 30 0a         10: . . . . . SEQUENCE
0119 06 03          3: . . . . . . OID 2.5.29.21: reasonCode
0124 04 03          3: . . . . . . OCTET STRING
                     : 0a 01 01
0129 30 09          9: . SEQUENCE
0131 06 07          7: . . OID 1.2.840.10040.4.3: dsa-with-sha
0140 03 2f         47: . BIT STRING  (0 unused bits)
                     : 30 2c 02 14 9e d8 6b c1 7d c2 c4 02 f5 17 84 f9
                     : 9f 46 7a ca cf b7 05 8a 02 14 9e 43 39 85 dc ea
                     : 14 13 72 93 54 5d 44 44 e5 05 fe 73 9a b2








Housley, Ford, Polk, & Solo                                   [Page 127]


INTERNET DRAFT                                             June 16, 1998


Appendix E. Author Addresses:

   Russell Housley
   SPYRUS
   381 Elden Street
   Suite 1120
   Herndon, VA 20170
   USA
   housley@spyrus.com

   Warwick Ford
   VeriSign, Inc.
   One Alewife Center
   Cambridge, MA 02140
   USA
   wford@verisign.com

   Tim Polk
   NIST
   Building 820, Room 426
   Gaithersburg, MD 20899
   USA
   wpolk@nist.gov

   David Solo
   Citicorp
   666 Fifth Ave, 3rd Floor
   New York, NY 10103
   USA
   david.solo@citicorp.com

Appendix F.  Full Copyright Statement

   Copyright (C) The Internet Society (date). All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  In addition, the
   ASN.1 modules presented in Appendices A and B may be used in whole or
   in part without inclusion of the copyright notice.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of develop-
   ing Internet standards in which case the procedures for copyrights
   defined in the Internet Standards process must be followed, or as



Housley, Ford, Polk, & Solo                                   [Page 128]


INTERNET DRAFT                                             June 16, 1998


   required to translate it into languages other than English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns. This
   document and the information contained herein is provided on an "AS
   IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK
   FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
   LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL
   NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY
   OR FITNESS FOR A PARTICULAR PURPOSE.









































Housley, Ford, Polk, & Solo                                   [Page 129]