PKIX Working Group R. Housley (SPYRUS)
Internet Draft W. Ford (VeriSign)
W. Polk (NIST)
D. Solo (Citigroup)
expires in six months March 2001
Internet X.509 Public Key Infrastructure
Certificate and CRL Profile
<draft-ietf-pkix-new-part1-05.txt>
Status of this Memo
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Copyright (C) The Internet Society (2001). All Rights Reserved.
Abstract
This is the fifth draft of a specification based upon RFC 2459. When
complete, this specification will obsolete RFC 2459. This
specification includes minor edits and clarifications. The most
notable departures from RFC 2459 are found in Section 6, Path
Validation. In RFC 2459, the reader was expected to augment the path
validation algorithm, which concentrated upon policy processing, with
information embedded in earlier sections. For example, parameter
inheritance is discussed in Section 7, Algorithm Support, and can
certainly affect the validity of a certification path. However,
parameter inheritance was omitted from the path validation algorithm
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in RFC 2459. In this draft, the path validation algorithm has a
comprehensive and extremely detailed description. Details such as
parameter inheritance are covered thoroughly. In addition, this
draft anticipates certain corrections proposed in the X.509 standard
for the policy processing aspects of path validation.
A new section 6.3, CRL validation, has been added as well. This
section provides a supplement to the path validation algorithm that
determines if a particular CRL may be used to verify the status of a
particular certificate. (The basic path validation algorithm is, by
design, independent of the type and format of status information.)
The most significant enhancement in draft five is a refinement of the
processing rules for path length constraints when applied to CA
certificates. This draft also completes the removal of processing
rules for unique identifiers. This was generally performed in the
fourth draft, but some details were overlooked. This draft also
incorporates significant corrections to the ASN.1 modules in the
appendices.
This memo profiles the X.509 v3 certificate and X.509 v2 CRL for use
in the Internet. An overview of the approach and model are provided
as an introduction. The X.509 v3 certificate format is described in
detail, with additional information regarding the format and
semantics of Internet name forms (e.g., IP addresses). Standard
certificate extensions are described and one new Internet-specific
extension is defined. A required set of certificate extensions is
specified. The X.509 v2 CRL format is described and a required
extension set is defined as well. An algorithm for X.509 certificate
path validation is described. Supplemental information is provided
describing the format of public keys and digital signatures in X.509
certificates for common Internet public key encryption algorithms
(i.e., RSA, DSA, and Diffie-Hellman). ASN.1 modules and examples are
provided in the appendices.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.
Please send comments on this document to the ietf-pkix@imc.org mail
list.
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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 ......................................... 19
4.1.2.3 Signature ............................................. 19
4.1.2.4 Issuer ................................................ 19
4.1.2.5 Validity .............................................. 23
4.1.2.5.1 UTCTime ............................................. 23
4.1.2.5.2 GeneralizedTime ..................................... 23
4.1.2.6 Subject ............................................... 24
4.1.2.7 Subject Public Key Info ............................... 25
4.1.2.8 Unique Identifiers .................................... 25
4.1.2.9 Extensions ............................................. 25
4.2 Certificate Extensions .................................... 25
4.2.1 Standard Extensions ..................................... 26
4.2.1.1 Authority Key Identifier .............................. 27
4.2.1.2 Subject Key Identifier ................................ 27
4.2.1.3 Key Usage ............................................. 29
4.2.1.4 Private Key Usage Period .............................. 30
4.2.1.5 Certificate Policies .................................. 31
4.2.1.6 Policy Mappings ....................................... 33
4.2.1.7 Subject Alternative Name .............................. 34
4.2.1.8 Issuer Alternative Name ............................... 36
4.2.1.9 Subject Directory Attributes .......................... 37
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4.2.1.10 Basic Constraints .................................... 37
4.2.1.11 Name Constraints ..................................... 38
4.2.1.12 Policy Constraints ................................... 40
4.2.1.13 Extended key usage field ............................. 41
4.2.1.14 CRL Distribution Points .............................. 42
4.2.1.15 Inhibit Any-Policy ................................... 43
4.2.1.16 Freshest CRL ......................................... 43
4.2.2 Internet Certificate Extensions ......................... 44
4.2.2.1 Authority Information Access .......................... 44
4.2.2.2 Subject Information Access ............................ 45
5 CRL and CRL Extensions Profile .............................. 47
5.1 CRL Fields ................................................ 47
5.1.1 CertificateList Fields .................................. 48
5.1.1.1 tbsCertList ........................................... 48
5.1.1.2 signatureAlgorithm .................................... 49
5.1.1.3 signatureValue ........................................ 49
5.1.2 Certificate List "To Be Signed" ......................... 49
5.1.2.1 Version ............................................... 49
5.1.2.2 Signature ............................................. 49
5.1.2.3 Issuer Name ........................................... 50
5.1.2.4 This Update ........................................... 50
5.1.2.5 Next Update ........................................... 50
5.1.2.6 Revoked Certificates .................................. 51
5.1.2.7 Extensions ............................................ 51
5.2 CRL Extensions ............................................ 51
5.2.1 Authority Key Identifier ................................ 51
5.2.2 Issuer Alternative Name ................................. 52
5.2.3 CRL Number .............................................. 52
5.2.4 Delta CRL Indicator ..................................... 52
5.2.5 Issuing Distribution Point .............................. 54
5.2.6 Freshest CRL ............................................ 55
5.3 CRL Entry Extensions ...................................... 55
5.3.1 Reason Code ............................................. 56
5.3.2 Hold Instruction Code ................................... 56
5.3.3 Invalidity Date ......................................... 57
5.3.4 Certificate Issuer ...................................... 57
6 Certificate Path Validation ................................. 58
6.1 Basic Path Validation ..................................... 58
6.1.1 Inputs ................................................... 61
6.1.2 Initialization ........................................... 62
6.1.3 Basic Certificate Processing ............................. 65
6.1.4 Preparation for Certificate i+1 .......................... 70
6.1.5 Wrap-up procedure ........................................ 73
6.1.6 Outputs .................................................. 74
6.2 Extending Path Validation ................................. 75
6.3 CRL Validation ............................................ 75
6.3.1 Revocation Inputs ....................................... 76
6.3.2 Initialization and Revocation State Variables ........... 76
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6.3.3 CRL Processing .......................................... 77
7 References .................................................. 79
8 Intellectual Property Rights ................................ 81
9 Security Considerations ..................................... 81
Appendix A. ASN.1 Structures and OIDs ......................... 85
A.1 Explicitly Tagged Module, 1988 Syntax ...................... 85
A.2 Implicitly Tagged Module, 1988 Syntax ...................... 98
Appendix B. ASN.1 Notes ....................................... 105
Appendix C. Examples .......................................... 106
C.1 Certificate ............................................... 107
C.2 Certificate ............................................... 110
C.3 End-Entity Certificate Using RSA .......................... 113
C.4 Certificate Revocation List ............................... 116
Appendix D. Author Addresses .................................. 118
Appendix E. Full Copyright Statement .......................... 118
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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
creation 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 particular, this document's relationship with the IETF
PEM specifications 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
Section 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
Section 6. These procedures are based upon the ISO/IEC/ITU
definition, but the presentation assumes one or more self-signed
trusted CA certificates. Implementations are required to derive the
same results but are not required to use the specified procedures.
Procedures for identification and encoding of public key materials
and digital signatures are defined in [PKIX ALGS]. Implementations of
this specification are not required to use any particular
cryptographic algorithms. However, conforming implementations which
use the algorithms identified in [PKIX ALGS] are required to identify
and encode the public key materials and digital signatures as
described in that specification.
Finally, three 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 notes on less familiar features of the ASN.1
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notation used within this specification. Appendix C 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
applications may include WWW, electronic mail, user authentication,
and IPsec. In order to relieve some of the obstacles to using X.509
certificates, 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
revocation 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
particular 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
conveying many authenticated attributes.
2.1 Communication and Topology
The users of certificates will operate in a wide range of
environments 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
availability. 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
revocation lists (CRLs) may be used.
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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
services determines the attributes contained in the certificate as
well as the ancillary control information in the certificate such as
policy 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
configuration responsibility (e.g., trusted CA keys, rules), explicit
platform usage constraints within the certificate, certification path
constraints 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 shall
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.
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+---+
| 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.
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3.1 X.509 Version 3 Certificate
Users of a public key require confidence 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
certificates, which are data structures that bind public key values
to subjects. The binding is asserted by having a trusted CA
digitally sign each certificate. The CA may base this assertion upon
technical means (a.k.a., proof of posession through a challenge-
response protocol), presentation of the private key, or on an
assertion by the subject. A certificate has a limited valid lifetime
which is indicated in its signed contents. Because a certificate's
signature and timeliness can be independently checked by a
certificate-using client, certificates can be distributed via
untrusted communications 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
recommendations, 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.
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
requirements, 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,
standardization 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
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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
for Internet WWW, electronic mail, and IPsec applications.
Environments 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
generally 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,
the CA's name, and related information (such as the validity period
or name constraints), 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
authority, 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
shall 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
electronic 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
organizations, particular organizational units (e.g., departments,
groups, sections), or particular geographical areas.
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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.
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
followed.
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
certificates. These restrictions included:
(a) a pure top-down hierarchy, with all certification paths
starting 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
architecture, 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
hierarchy. 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
concept, which permits a greater degree of automation. The
application can determine if the certification path is acceptable
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based on the contents of the certificates instead of a priori
knowledge of PCAs. This permits automation of certificate chain
processing.
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
association 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
policy, 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
distributed by exactly the same means as certificates themselves,
namely, via untrusted communications and server systems.
One limitation of the CRL revocation method, using untrusted
communications 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 all currently issued CRLs
are updated -- 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
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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
specifications. On-line methods of revocation notification may be
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
needs to 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.
Provision 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
appropriate relationship with keys stored elsewhere in the
infrastructure. For example, the client needs to be securely
initialized with the public key and other assured information of
the trusted CA(s), to be used in validating certificate paths.
Furthermore, a client typically needs to be initialized with its
own key pair(s).
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(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.
(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
forgotten 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
certificate issued by one CA to another CA which contains a CA
signature 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
combined into one protocol exchange. In particular, two or more of
the registration, initialization, and certification functions can be
combined into one protocol exchange.
The PKIX series of specifications may define a set of standard
message 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
syntax, the encoded certificate and standard extensions are
equivalent. This section also defines private extensions required to
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support a PKI for the Internet community.
Certificates may be used in a wide range of applications and
environments covering a broad spectrum of interoperability goals and
a broader spectrum of operational and assurance requirements. The
goal of this document is to establish a common baseline for generic
applications 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 shall be v2 or v3
subjectUniqueID [2] IMPLICIT UniqueIdentifier OPTIONAL,
-- If present, version shall be v2 or v3
extensions [3] EXPLICIT Extensions OPTIONAL
-- If present, version shall be v3
}
Version ::= INTEGER { v1(0), v2(1), v3(2) }
CertificateSerialNumber ::= INTEGER
Validity ::= SEQUENCE {
notBefore Time,
notAfter Time }
Time ::= CHOICE {
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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 }
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
cryptographic algorithm used by the CA to sign this certificate.
[PKIX ALGS] 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
algorithm. 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. [PKIX ALGS]
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lists the supported algorithms for this specification.
This field MUST contain the same algorithm identifier as the
signature field in the sequence tbsCertificate (see sec. 4.1.2.3).
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
tbsCertificate 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 Certificate's signature field. The details of this process are
specified for each of the supported algorithms in [PKIX ALGS].
By generating this signature, a CA certifies the validity of the
information in the tbsCertificate field. In particular, the CA
certifies 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
TBSCertificate 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. Extensions 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 MUST recognize version 3
certificates.
Generation of version 2 certificates is not expected by
implementations based on this profile.
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4.1.2.2 Serial number
The serial number MUST be a positive integer assigned by the CA to
each certificate. It MUST be unique for each certificate issued by a
given CA (i.e., the issuer name and serial number identify a unique
certificate). CAs MUST force the serialNumber to be a non-negative
integer.
Given the uniqueness requirements above serial numbers can be
expected to contain long integers. Certificate users MUST be able to
handle serialNumber values up to 20 octets. Conformant CAs MUST NOT
use serialNumber values longer than 20 octets.
Note: Non-conforming CAs may issue certificates with serial numbers
that are negative, or zero. Certificate users SHOULD be prepared to
handle such certificates.
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
signatureAlgorithm 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. [PKIX ALGS] 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 MUST contain a non-empty distinguished
name (DN). The issuer field is defined as the X.501 type Name.
[X.501] 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
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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. The
UTF8String encoding is the preferred encoding, and all certificates
issued after December 31, 2003 MUST use the UTF8String encoding of
DirectoryString (except as noted below). Until that date, conforming
CAs MUST choose from the following options when creating a
distinguished name, including their own:
(a) if the character set is sufficient, the string MAY be
represented as a PrintableString;
(b) failing (a), if the BMPString character set is sufficient the
string MAY be represented as a BMPString; and
(c) failing (a) and (b), the string MUST be represented as a
UTF8String. If (a) or (b) is satisfied, the CA MAY still choose
to represent the string as a UTF8String.
Exceptions to the December 31, 2003 UTF8 encoding requirements are as
follows:
(a) CAs MAY issue "name rollover" certificates to support an
orderly migration to UTF8String encoding. Such certificates would
include the CA's UTF8String encoded name as issuer and and the old
name encoding as subject, or vice-versa.
(b) As stated in section 4.1.2.6, the subject field MUST be
populated with a non-empty distinguished name matching the
contents of the issuer field in all certificates issued by the
subject CA regardless of encoding.
The TeletexString and UniversalString are included for backward
compatibility, and should not be used for certificates for new
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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 types.
In addition, many legacy implementations support names encoded in the
ISO 8859-1 character set (Latin1String) but tag them as
TeletexString. The Latin1String includes characters used in Western
European countries which are not part of the TeletexString charcter
set. Implementations that process TeletexString SHOULD be prepared
to handle the entire ISO 8859-1 character set.[ISO 8859-1]
As noted above, distinguished names are composed of attributes. This
specification does not restrict the set of attribute types that may
appear in names. However, conforming implementations MUST be
prepared to receive certificates with issuer names containing the set
of attribute types defined below. This specification also recommends
support for additional attribute types.
Standard sets of attributes have been defined in the X.500 series of
specifications.[X.520] Implementations of this specification MUST be
prepared to receive the following standard attribute types in issuer
and subject (see 4.1.2.6) names:
* country,
* organization,
* organizational-unit,
* distinguished name qualifier,
* state or province name,
* common name (e.g., "Susan Housley"), and
* serial number.
In addition, implementations of this specification SHOULD be prepared
to receive the following standard attribute types in issuer and
subject names:
* locality,
* title,
* surname,
* given name,
* initials,
* pseudonym, and
* generation qualifier (e.g., "Jr.", "3rd", or "IV").
The syntax and associated object identifiers (OIDs) for these
attribute types are provided in the ASN.1 modules in Appendices A and
B.
In addition, implementations of this specification MUST be prepared
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to receive the domainComponent attribute, as defined in [RFC 2247].
The Domain (Nameserver) System (DNS) provides a hierarchical resource
labeling system. This attribute provides is a convenient mechanism
for organizations that wish to use DNs that parallel their DNS names.
This is not a replacement for the dNSName component of the
alternative name field. Implementations are not required to convert
such names into DNS names. The syntax and associated OID for this
attribute type is provided in the ASN.1 modules in Appendices A and
B.
Certificate users MUST be prepared to process the issuer
distinguished 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 a CA
certificate.
This specification requires only a subset of the name comparison
functionality specified in the X.500 series of specifications. The
requirements for conforming implementations are as follows:
(a) attribute values encoded in different types (e.g.,
PrintableString and BMPString) may be assumed to represent
different strings;
(b) attribute values in 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
(d) attribute values in PrintableString are compared after
removing leading and trailing white space and converting internal
substrings 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.
In addition, implementations of this specification MAY use these
comparison rules to process unfamiliar attribute types for name
chaining. This allows implementations to process certificates with
unfamiliar attributes in the issuer name.
Note that the comparison rules defined in the X.500 series of
specifications indicate that the character sets used to encode data
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in distinguished names are irrelevant. The characters themselves are
compared without regard to encoding. Implementations of the profile
are permitted to use the comparison algorithm defined in the X.500
series. Such an implementation will recognize a superset of name
matches recognized by the algorithm specified above.
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 MUST always encode certificate
validity dates through the year 2049 as UTCTime; certificate validity
dates in 2050 or later MUST be encoded as GeneralizedTime.
The validity period for a certificate is the period of time from
notBefore through notAfter, inclusive.
4.1.2.5.1 UTCTime
The universal time type, UTCTime, is a standard ASN.1 type intended
for representation of dates and time. 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 MUST be expressed
Greenwich Mean Time (Zulu) and MUST include seconds (i.e., times are
YYMMDDHHMMSSZ), even where the number of seconds is zero. Conforming
systems MUST interpret the year field (YY) as follows:
Where YY is greater than or equal to 50, the year shall be
interpreted 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
GeneralizedTime field can include a representation of the time
differential between local and Greenwich Mean Time.
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For the purposes of this profile, GeneralizedTime values MUST be
expressed Greenwich Mean Time (Zulu) and MUST include seconds (i.e.,
times are YYYYMMDDHHMMSSZ), even where the number of seconds is zero.
GeneralizedTime values MUST 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
discussed in 4.2.1.10, is present and the value of cA is TRUE,) then
the subject field MUST be populated with a non-empty 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 MUST contain an X.500
distinguished 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
subject entity.
The subject name field is defined as the X.501 type Name.
Implementation requirements for this field are those defined for the
issuer field (see sec. 4.1.2.4). When encoding attribute values of
type DirectoryString, the encoding rules for the issuer field MUST be
implemented. Implementations of this specification MUST be prepared
to receive subject names containing the attribute types required for
the issuer field. Implementations of this specification SHOULD be
prepared to receive subject names containing the recommended
attribute types for the issuer field. The syntax and associated
object identifiers (OIDs) for these attribute types are provided in
the ASN.1 modules in Appendices A and B. Implementations of this
specification MAY use these comparison rules to process unfamiliar
attribute types (i.e., for name chaining). This allows
implementations to process certificates with unfamiliar attributes in
the subject name.
In addition, legacy implementations exist where an RFC 822 name is
embedded in the subject distinguished name as an EmailAddress
attribute. The attribute value for EmailAddress is of type IA5String
to permit inclusion of the character '@', which is not part of the
PrintableString character set. EmailAddress attribute values are not
case sensitive (e.g., "fanfeedback@redsox.com" is the same as
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"FANFEEDBACK@REDSOX.COM").
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
identities. Simultaneous inclusion of the EmailAddress attribute in
the subject distinguished name to support legacy implementations is
deprecated but permitted.
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 [PKIX ALGS].
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
conforming 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
format also allows communities to define private extensions to carry
information unique to those communities. Each extension in a
certificate 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 may be ignored if it is not recognized. The following
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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 adopting 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
extension may appear in a particular certificate. For example, a
certificate 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 MUST 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
identified within this specification; certificate issuers are
cautioned that marking such extensions as critical may inhibit
interoperability.
At a minimum, applications conforming to this profile MUST recognize
the following extensions: key usage (see sec. 4.2.1.3), certificate
policies (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), extended
key usage (see sec. 4.2.1.13), and inhibit any-policy (see sec.
4.2.1.15).
In addition, this profile RECOMMENDS application support for the
authority and subject key identifier (see sec. 4.2.1.1 and 4.2.1.2),
and policy mapping (see sec. 4.2.1.6) 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 id-ce
arc, which is defined by the following:
id-ce OBJECT IDENTIFIER ::= {joint-iso-ccitt(2) ds(5) 29}
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4.2.1.1 Authority Key Identifier
The authority key identifier extension provides a means of
identifying 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 identifier (the subject key identifier in the issuer's
certificate) or on the issuer name and serial number.
The keyIdentifier field of the authorityKeyIdentifier extension MUST
be included in all certificates generated by conforming CAs to
facilitate chain building. 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.
The value of the keyIdentifier field SHOULD be derived from the
public key used to verify the certificate's signature or a method
that generates unique values. Two common methods for generating key
identifiers from the public key are described in (sec. 4.2.1.2). One
common method for generating unique values is described in (sec.
4.2.1.2). Where a key identifier has not been previously
established, this specification recommends use of one of these
methods for generating keyIdentifiers.
This profile recommends support for the key identifier method by all
certificate users.
This extension MUST 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
certificates that contain a particular public key.
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
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is TRUE. The value of the subject key identifier MUST 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.
For CA certificates, subject key identifiers SHOULD be derived from
the public key or a method that generates unique values. The key
identifier is an explicit value placed in the certificate by the
issuer, not a value generated by a certificate user. Two common
methods for generating key identifiers from the public key are:
(1) The keyIdentifier is composed of the 160-bit SHA-1 hash of the
value of the BIT STRING subjectPublicKey (excluding the tag,
length, and number of unused bits).
(2) 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 value of the BIT STRING subjectPublicKey.
One common method for generating unique values is a monotonically
increasing sequence of integers.
For end entity certificates, the subject key identifier extension
provides a means for identifying certificates containing the
particular public key used in an application. Where an end entity has
obtained multiple certificates, especially from multiple CAs, the
subject key identifier provides a means to quickly identify the set
of certificates containing a particular public key. To assist
applications in identifying the appropriate end entity certificate,
this extension SHOULD be included in all end entity certificates.
For end entity certificates, subject key identifiers SHOULD be
derived from the public key. Two common methods for generating key
identifiers from the public key are identifed above.
Where a key identifier has not been previously established, this
specification recommends use of one of these methods for generating
keyIdentifiers.
This extension MUST NOT be marked critical.
id-ce-subjectKeyIdentifier OBJECT IDENTIFIER ::= { id-ce 14 }
SubjectKeyIdentifier ::= KeyIdentifier
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4.2.1.3 Key Usage
The key usage extension defines the purpose (e.g., encipherment,
signature, 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 critical.
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 with a digital signature mechanism to support security
services other than non-repudiation (bit 1), certificate signing
(bit 5), or revocation information signing (bit 6). Digital
signature mechanisms are often used for entity authentication and
data origin authentication with integrity.
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.
In the case of later conflict, a reliable third party may
determine the authenticity of the signed data.
Further distinctions between the digitalSignature and
nonRepudiation bits may be provided in specific certificate
policies.
The keyEncipherment bit is asserted when the subject public key is
used for key transport. For example, when an RSA key is to be
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used for key management, then this bit shall 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 shall 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. If the keyCertSign bit is
asserted, then the cA bit in the basic constraints extension (see
4.2.1.10) MUST also be asserted. If the keyCertSign bit is not
asserted, then the cA bit in the basic constraints extension MUST
NOT be asserted.
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 [PKIX ALGS].
4.2.1.4 Private Key Usage Period
This profile recommends against the use of this extension. CAs
conforming to this profile MUST 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
signature keys. This extension consists of two optional components,
notBefore and notAfter. The private key associated with the
certificate should not be used to sign objects before or after the
times specified by the two components, respectively. CAs conforming
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to this profile MUST NOT generate certificates with private key usage
period extensions unless at least one of the two components is
present.
Where used, notBefore and notAfter are represented as GeneralizedTime
and MUST 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
identifier (OID) and optional qualifiers. Optional qualifiers, which
may be present, are not expected to change the definition of the
policy.
In an end-entity certificate, these policy information terms indicate
the policy under which the certificate has been issued and the
purposes for which the certificate may be used. In a CA certificate,
these policy information terms limit the set of policies for
certification paths which include this certificate. When a CA does
not wish to limit the set of policies for certification paths which
include this certificate, they may assert the special policy
anyPolicy, with a value of {2 5 29 32 0}.
Applications with specific policy requirements are expected to have a
list of those policies which they will accept and to compare the
policy OIDs in the certificate to that list. If this extension is
critical, the path validation software MUST be able to interpret this
extension (including the optional qualifier), or MUST reject the
certificate.
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. When qualifiers are
used with the special policy anyPolicy, they MUST be limited to the
qualifers identified in this section.
This specification defines two policy qualifier types for use by
certificate policy writers and certificate issuers. The qualifier
types are the CPS Pointer and User Notice qualifiers.
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The CPS Pointer qualifier contains a pointer to a Certification
Practice Statement (CPS) published by the CA. The pointer is in the
form of a URI. Processing requirements for this qualifier are a
local matter. No action is mandated by this specification regardless
of the criticality value asserted for the extension.
User notice is intended for display to a relying party when a
certificate 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 organizations.
The user notice has two optional fields: the noticeRef field and the
explicitText field.
The noticeRef field, if used, names an organization and
identifies, 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
maximum 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 }
anyPolicy OBJECT IDENTIFIER ::= {id-ce-certificate-policies 0}
certificatePolicies ::= SEQUENCE SIZE (1..MAX) OF PolicyInformation
PolicyInformation ::= SEQUENCE {
policyIdentifier CertPolicyId,
policyQualifiers SEQUENCE SIZE (1..MAX) OF
PolicyQualifierInfo OPTIONAL }
CertPolicyId ::= OBJECT IDENTIFIER
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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,
userNotice UserNotice }
CPSuri ::= IA5String
UserNotice ::= SEQUENCE {
noticeRef NoticeReference OPTIONAL,
explicitText DisplayText OPTIONAL}
NoticeReference ::= SEQUENCE {
organization DisplayText,
noticeNumbers SEQUENCE OF INTEGER }
DisplayText ::= CHOICE {
ia5String IA5String (SIZE (1..200)),
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
subjectDomainPolicy. The pairing indicates the issuing CA considers
its issuerDomainPolicy equivalent to the subject CA's
subjectDomainPolicy.
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.
Each issuerDomainPolicy named in the the policy mapping extension
should also be asserted in a certificate policies extension in the
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same certificate. Policies should not be mapped either to or from
the special value anyPolicy. (See 4.2.1.5 certificate policies).
This extension may be supported by CAs and/or applications, and it
MUST be 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 identifier (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
alternative name (or issuer alternative name) extension MUST be used.
Because the subject alternative name is considered to be definitively
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 MUST be empty (an empty sequence), and the
subjectAltName extension MUST be present. If the subject field
contains an empty sequence, the subjectAltName extension MUST be
marked critical.
When the subjectAltName extension contains an Internet mail address,
the address MUST 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
">". Note that while upper and lower case letters are allowed in an
RFC 822 addr-spec, no significance is attached to the case.
When the subjectAltName extension contains a iPAddress, the address
MUST 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
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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 MUST be stored in the dNSName (an IA5String).
The name MUST 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) MUST NOT be used; such identities are to
be encoded as rfc822Name.
Note: work is currently underway to specify domain names in
international character sets. This names will likely not be
accomodated by IA5String. Once this work is complete, this profile
will be revisited and the appropriate functionality will be added.
When the subjectAltName extension contains a URI, the name MUST be
stored in the uniformResourceIdentifier (an IA5String). The name MUST
be a non-relative URL, and MUST follow the URL syntax and encoding
rules specified in [RFC 1738]. The name must include both a scheme
(e.g., "http" or "ftp") and a scheme-specific-part. The scheme-
specific-part must include a fully qualified domain name or IP
address as the host.
As specified in [RFC 1738], the scheme name is not case-sensitive
(e.g., "http" is equivalent to "HTTP"). The host part is also not
case-sensitive, but other components of the scheme-specific-part may
be case-sensitive. When comparing URIs, conforming implementations
MUST compare the scheme and host without regard to case, but assume
the remainder of the scheme-specific-part is case sensitive.
When the subjectAltName extension contains a DN in the directoryName,
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 subject entity.
The subjectAltName may carry additional name types through the use of
the otherName field. The format and semantics of the name are
indicated through the OBJECT IDENTIFIER in the type-id field. The
name itself is conveyed as value field in otherName. For example,
Kerberos [RFC 1510] format names can be encoded into the otherName,
using the krb5PrincipalName OID and the KerberosName syntax as
defined in [PKINIT].
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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.
If the subjectAltName extension is present, the sequence MUST contain
at least one entry. Unlike the subject field, conforming CAs MUST
NOT issue certificates with subjectAltNames containing empty
GeneralName 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 shall 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 MUST
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be encoded as in 4.2.1.7.
Where present, this extension SHOULD NOT be marked critical.
id-ce-issuerAltName OBJECT IDENTIFIER ::= { id-ce 18 }
IssuerAltName ::= GeneralNames
4.2.1.9 Subject Directory Attributes
The subject directory attributes extension is used to convey
identification attributes (e.g.,nationality) of the subject. The
extension is defined as a sequence of one or more attributes. This
extension MUST be 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 cA bit indicates if the certified public key may be used to
verify signatures on other certificates. If the cA bit is asserted,
then the keyCertSign bit in the key usage extension (see 4.2.1.3)
MUST also be asserted. If the cA bit is not asserted, then the
keyCertSign bit in the key usage extension MUST NOT be asserted.
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. (Note: The last
certificate may be an end-entity certificate or a CA certificate.
The cA bit, or its absence, determines the type of the last
certificate rather than the application.) A pathLenConstraint 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 MUST appear as a critical extension in all CA
certificates. This extension MAY appear as a critical or non-
critical extension in end entity certificates.
id-ce-basicConstraints OBJECT IDENTIFIER ::= { id-ce 19 }
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BasicConstraints ::= SEQUENCE {
cA BOOLEAN DEFAULT FALSE,
pathLenConstraint INTEGER (0..MAX) OPTIONAL }
4.2.1.11 Name Constraints
The name constraints extension, which MUST be used only in a CA
certificate, indicates a name space within which all subject names in
subsequent certificates in a certification path shall 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.
Name constraints are not applied to certificates whose issuer and
subject are identical. (This could prevent CAs that use name
constraints from issuing self-signed certificates to implement key
rollover.)
Restrictions are defined in terms of permitted or excluded name
subtrees. Any name matching a restriction in the excludedSubtrees
field is invalid regardless of information appearing in the
permittedSubtrees. 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.
For URIs, the constraint applies to the host part of the name. The
constraint may specify a host or a domain. Examples would be
"foo.bar.com"; and ".xyz.com". When the the constraint begins with
a period, it may be expanded 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". When the constraint does not begin with a period, it
specifies a host.
A name constraint for Internet mail addresses may specify a
particular mailbox, all addresses at a particular host, or all
mailboxes in a domain. To indicate a particular mailbox, the
constraint is the complete mail address. For example, "root@xyz.com"
indicates the root mailbox on the host "xyz.com". To indicate all
Internet mail addresses on a particular host, the constraint is
specified as the host name. For example, the constraint "xyz.com" is
satisfied by any mail address at the host "xyz.com". To specify any
address within a domain, the constraint is specified with a leading
period (as with URIs). For example, ".xyz.com" indicates all the
Internet mail addresses in the domain "xyz.com", but not Internet
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mail addresses on the host "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 in an attribute of type EmailAddress (see
sec. 4.1.2.6). When rfc822 names are constrained, but the certificate
does not include a subject alternative name, the rfc822 name
constraint MUST be applied to the attribute of type EmailAddress in
the subject distinguished name. The ASN.1 syntax for EmailAddress
and the corresponding OID are supplied in Appendix A and B.
Restrictions of the form directoryName MUST be applied to the subject
field in the certificate and to the subjectAltName extensions of type
directoryName. Restrictions of the form x400Address MUST be applied
to subjectAltName extensions of type x400Address.
When applying restrictions of the form directoryName, an
implementation MUST compare DN attributes. At a minimum,
implementations MUST perform the DN comparison rules specified in
Section 4.1.2.4. CAs issuing certificates with a restriction of the
form directoryName SHOULD NOT rely on implementation of the full ISO
DN name comparison algorithm. This implies name restrictions shall
be stated identically to the encoding used in the subject field or
subjectAltName extension.
The syntax of iPAddress MUST 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 MUST contain eight (8)
octets, encoded in the style of RFC 1519 (CIDR) to represent an
address range.[RFC 1519] For IPv6 addresses, the ipAddress field
MUST 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,
ediPartyName, 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 }
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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
identifier.
If the inhibitPolicyMapping field is present, the value indicates the
number of additional certificates that may appear in the path before
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
certificates in the path.
If the requireExplicitPolicy field is present, subsequent
certificates shall 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 MUST 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 }
PolicyConstraints ::= SEQUENCE {
requireExplicitPolicy [0] SkipCerts OPTIONAL,
inhibitPolicyMapping [1] SkipCerts OPTIONAL }
SkipCerts ::= INTEGER (0..MAX)
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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
purposes indicated in the key usage extension field. In general,
this extension will appear only in end entity certificates. 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
accordance with IANA or ITU-T Rec. X.660 | ISO/IEC/ITU 9834-1.
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 MUST only
be used for one of the purposes indicated. If multiple purposes are
indicated the application need not recognize all purposes indicated,
as long as the intended purpose is present and recognized.
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
certificate to be acceptable to that application.
If a certificate contains both a critical key usage field and a
critical extended key usage field, then both fields MUST be processed
independently and the certificate MUST only be used for a purpose
consistent with both fields. If there is no purpose consistent with
both fields, then the certificate MUST 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,
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-- 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,
-- 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.
The cRLDistributionPoints extension is a SEQUENCE of
DistributionPoint. A DistributionPoint consists of three fields,
each of which is optional: the name of the DistributionPoint,
ReasonsFlags, and the cRLIssuer. While each component is optional, a
DistributionPoint MUST NOT consist of only the ReasonsFlags field. If
the distributionPoint omits cRLIssuer, the CRL MUST be issued by the
CA that issued the certificate. If the distributionPointName is
absent, cRLIssuer MUST be present and include a Name corresponding to
an X.500 or LDAP directory entry where the CRL is located.
If the cRLDistributionPoints extension contains a
DistributionPointName of type URI, the following semantics MUST 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
distributionPoint omits reasons, the CRL MUST include revocations for
all reasons.
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id-ce-cRLDistributionPoints OBJECT IDENTIFIER ::= { id-ce 31 }
CRLDistributionPoints ::= 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) }
4.2.1.15 Inhibit Any-Policy
The inhibit any-policy extension can be used in certificates issued
to CAs. The inhibit any-policy indicates that the special any-policy
OID, with the value {2 5 29 32 0}, is not considered an explicit
match for other certificate policies. The value indicates the number
of additional certificates that may appear in the path before any-
policy is no longer permitted. For example, a value of one indicates
that any-policy may be processed in certificates issued by the
subject of this certificate, but not in additional certificates in
the path.
This extension MUST be critical.
id-ce-inhibitAnyPolicy OBJECT IDENTIFIER ::= { id-ce 54 }
InhibitAnyPolicy ::= SkipCerts
SkipCerts ::= INTEGER (0..MAX)
4.2.1.16 Freshest CRL (a.k.a. Delta CRL Distribution Point)
The freshest CRL extension identifies how delta-CRL information is
obtained. The extension MUST be non-critical. Further discussion of
CRL management is contained in section 5.
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The same syntax is used for this extension and the
cRLDistributionPoints extension, and is described in section
4.2.1.14. The same conventions apply to both extensions.
id-ce-freshestCRL OBJECT IDENTIFIER ::= { id-ce 46 }
FreshestCRL ::= CRLDistributionPoints
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
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
format 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
extensions defined for the Internet PKI will also be defined under
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 MUST be non-critical.
id-pe-authorityInfoAccess OBJECT IDENTIFIER ::= { id-pe 1 }
AuthorityInfoAccessSyntax ::=
SEQUENCE SIZE (1..MAX) OF AccessDescription
AccessDescription ::= SEQUENCE {
accessMethod OBJECT IDENTIFIER,
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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 provided by 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.
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
protocol 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 MUST be a uniformResourceIdentifier. Where the
information is available via the directory access protocol (dap),
accessLocation MUST be a directoryName. When the information is
available via electronic mail, accessLocation MUST be an rfc822Name.
The semantics of other name forms of accessLocation (when
accessMethod is id-ad-caIssuers) are not defined by this
specification.
[RFC 2560] defines the access descriptor for the Online Certificate
Status Protocol. When this access descriptor appears in the
authority information access extension, this indicates the issuer
provides revocation information for this certificate through the
named OCSP service. Additional access descriptors may be defined in
other PKIX specifications.
4.2.2.2 Subject Information Access
The subject information access extension indicates how to access
information and services for the subject of the certificate in which
the extension appears. When the subject is a CA, information and
services may include certificate validation services and CA policy
data. When the subject is an end entity, the information describes
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the type of services offered and how to access them. In this case,
the contents of this extension are defined in the protocol
specifications for the suported services. This extension may be
included in subject or CA certificates, and it MUST be non-critical.
id-pe-subjectInfoAccess OBJECT IDENTIFIER ::= { id-pe 11 }
SubjectInfoAccessSyntax ::=
SEQUENCE SIZE (1..MAX) OF AccessDescription
AccessDescription ::= SEQUENCE {
accessMethod OBJECT IDENTIFIER,
accessLocation GeneralName }
Each entry in the sequence SubjectInfoAccessSyntax describes the
format and location of additional information provided by the subject
of 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.
This profile defines one access method to be used when the subject is
a CA, and one access method to be used when the subject is an end
entity. Additional access methods may be defined in the future in
the protocol specifications for other services.
The id-ad-caRepository OID is used when the subject is a CA, and
publishes its certificates and CRLs (if issued) in a repository. The
accessLocation field is defined as a GeneralName, which can take
several forms. Where the information is available via http, ftp, or
ldap, accessLocation MUST be a uniformResourceIdentifier. Where the
information is available via the directory access protocol (dap),
accessLocation MUST be a directoryName. When the information is
available via electronic mail, accessLocation MUST be an rfc822Name.
The semantics of other name forms of of accessLocation (when
accessMethod is id-ad-caRepository) are not defined by this
specification.
The id-ad-timeStamping OID is used when the subject offers
timestamping services using the Time Stamp Protocol defined in [PKIX
TSA]. Where the timestamping services are available via http or ftp,
accessLocation MUST be a uniformResourceIdentifier. Where the
timestamping services are available via electronic mail,
accessLocation MUST be an rfc822Name. Where timestamping services
are available using TCP/IP, the dNSName and ipAddress name forms may
be used. The semantics of other name forms of accessLocation (when
accessMethod is id-ad-timeStamping) are not defined by this
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specification.
Additional access descriptors may be defined in other PKIX
specifications.
id-ad OBJECT IDENTIFIER ::= { id-pkix 48 }
id-ad-caRepository OBJECT IDENTIFIER ::= { id-ad 5 }
id-ad-timeStamping OBJECT IDENTIFIER ::= { id-ad 3 }
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
specified, 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
attributes 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 MUST issue version 2 CRLs, and CAs MUST include the date
by which the next CRL will be issued in the nextUpdate field (see
sec. 5.1.2.5), the CRL number extension (see sec. 5.2.3) and the
authority key identifier extension (see sec. 5.2.1). 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
encoding is a tag, length, value encoding system for each element.
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CertificateList ::= SEQUENCE {
tbsCertList TBSCertList,
signatureAlgorithm AlgorithmIdentifier,
signatureValue BIT STRING }
TBSCertList ::= SEQUENCE {
version Version OPTIONAL,
-- if present, shall be v2
signature AlgorithmIdentifier,
issuer Name,
thisUpdate Time,
nextUpdate Time OPTIONAL,
revokedCertificates SEQUENCE OF SEQUENCE {
userCertificate CertificateSerialNumber,
revocationDate Time,
crlEntryExtensions Extensions OPTIONAL
-- if present, shall be v2
} OPTIONAL,
crlExtensions [0] EXPLICIT Extensions OPTIONAL
-- if present, shall 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.
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 optional list of revoked
certificates, and optional CRL extensions. When there are no revoked
certificates, the revoked certificates list is absent. When one or
more certificates are revoked, each entry on the revoked certificate
list is defined by a sequence of user certificate serial number,
revocation date, and optional CRL entry extensions.
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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.
[PKIX ALGS] lists the supported algorithms for this specification.
Conforming CAs MUST use the algorithm identifiers presented in [PKIX
ALGS] when signing with a supported signature algorithm.
This field MUST contain the same algorithm identifier as the
signature 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
signatureValue field. The details of this process are specified for
each of the supported algorithms in [PKIX ALGS].
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
extensions. 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 MUST be
present and MUST 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. [PKIX ALGS] lists OIDs for the most popular
signature algorithms used in the Internet PKI.
This field MUST contain the same algorithm identifier as the
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signatureAlgorithm 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.
Alternative name forms may also appear in the issuerAltName extension
(see sec. 5.2.2). The issuer name field MUST contain an X.500
distinguished name (DN). The issuer name field is defined as the
X.501 type Name, and MUST 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 MUST encode thisUpdate
as UTCTime for dates through the year 2049. CAs conforming to this
profile that issue CRLs MUST encode thisUpdate as GeneralizedTime for
dates in the year 2050 or later.
Where encoded as UTCTime, thisUpdate MUST be specified and
interpreted as defined in section 4.1.2.5.1. Where encoded as
GeneralizedTime, thisUpdate MUST 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. CAs SHOULD issue
CRLs with a nextUpdate time equal to or later than all previous CRLs.
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
omit nextUpdate is not specified by this profile.
CAs conforming to this profile that issue CRLs MUST encode nextUpdate
as UTCTime for dates through the year 2049. CAs conforming to this
profile that issue CRLs MUST encode nextUpdate as GeneralizedTime for
dates in the year 2050 or later.
Where encoded as UTCTime, nextUpdate MUST be specified and
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interpreted as defined in section 4.1.2.5.1. Where encoded as
GeneralizedTime, nextUpdate MUST be specified and interpreted as
defined in section 4.1.2.5.2.
5.1.2.6 Revoked Certificates
When there are no revoked certificates, the revoked certificates list
is absent. Otherwise, revoked certificates are listed by their
serial numbers. Certificates revoked by the CA are uniquely
identified by the certificate serial number. The date on which the
revocation occurred is specified. The time for revocationDate MUST
be expressed as described in section 5.1.2.4. Additional information
may be supplied in CRL entry extensions; CRL entry extensions are
discussed 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.
Communities 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.
5.2.1 Authority Key Identifier
The authority key identifier extension provides a means of
identifying 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
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is especially useful where an issuer has more than one signing key,
either due to multiple concurrent key pairs or due to changeover.
Conforming CAs MUST use the key identifier method, and MUST 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
alternative name extension MUST 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
monotonically 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 MUST 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
CRL as being a delta CRL. Delta CRLs contain updates to revocation
information previously distributed, rather than all the information
that would appear in a complete CRL. The use of delta CRLs can
significantly reduce network load and processing time in some
environments. Delta CRLs are generally smaller than the CRLs they
update, so applications that obtain delta CRLs consume less network
bandwidth than applications that obtain the corresponding complete
CRLs. Applications which store revocation information in a format
other than the CRL structure can add new revocation information to
the local database without reprocessing information.
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The delta CRL indicator extension contains a single value of type
BaseCRLNumber. This value identifies the CRL number of the base CRL
that was used as the foundation in the generation of this delta CRL.
The referenced base CRL is a CRL that was explicitly issued as a CRL
that is complete for a given scope (e.g., a set of revocation reasons
or a particular distribution point.) The CRL containing the delta CRL
indicator extension contains all updates to the certificate
revocation status for that same scope. The combination of a CRL
containing the delta CRL indicator extension plus the CRL referenced
in the BaseCRLNumber component of this extension is equivalent to a
full CRL, for the applicable scope, at the time of publication of the
delta CRL.
When a conforming CA issues a delta CRL, the CA MUST also issue a CRL
that is complete for the given scope. Both the delta CRL and the
complete CRL MUST include the CRL number extension (see sec. 5.2.3).
The CRL number extension in the delta CRL and the complete CRL MUST
contain the same value. When a delta CRL is issued, it MUST cover
the same set of reasons and same set of certificates that were
covered by the base CRL it references.
An application can construct a CRL that is complete for a given
scope, at the current time, in either of the following ways:
(a) by retrieving the current delta CRL for that scope, and
combining it with an issued CRL that is complete for that scope
and that has a cRLNumber greater than or equal to the cRLNumber of
the base CRL referenced in the delta CRL; or
(b) by retrieving the current delta CRL for that scope and
combining it with a locally constructed CRL whose cRLNumber is
greater than or equal to the cRLNumber of the base CRL referenced
in the current delta CRL.
The constructed CRL has the CRL number specified in the CRL number
extension found in the delta CRL used in its construction.
CAs must ensure that application of a delta CRL to the referenced
base revocation information accurately reflects the current status of
revocation. If a CA supports the certificateHold revocation reason
the following rules must be applied when generating delta CRLs:
(a) If a certificate was listed as revoked with revocation reason
certificateHold on a CRL (either a delta CRL or a CRL that is
complete for a given scope), whose cRLNumber is n, and the hold is
subsequently released, the certificate must be included in all
delta CRLs issued after the hold is released where the cRLNumber
of the referenced base CRL is less than or equal to n. The
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certificate must be listed with revocation reason removeFromCRL
unless the certificate is subsequently revoked again for one of
the revocation reasons covered by the delta CRL, in which case the
certificate must be listed with the revocation reason appropriate
for the subsequent revocation.
(b) If the certificate was not removed from hold, but was
permanently revoked, then it must be listed on all subsequent
delta CRLs where the cRLNumber of the referenced base CRL is less
than the cRLNumber of the CRL (either a delta CRL or a CRL that is
complete for the given scope) on which the permanent revocation
notice first appeared.
id-ce-deltaCRLIndicator OBJECT IDENTIFIER ::= { id-ce 27 }
deltaCRLIndicator EXTENSION ::= {
SYNTAX BaseCRLNumber
IDENTIFIED BY id-ce-deltaCRLIndicator }
BaseCRLNumber ::= CRLNumber
5.2.5 Issuing Distribution Point
The issuing distribution point is a critical CRL extension that
identifies the CRL distribution point for a particular CRL, and it
indicates whether the CRL covers revocation for end entity
certificates only, CA certificates only, or a limited 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.
The reason codes associated with a distribution point shall be
specified in onlySomeReasons. If onlySomeReasons does not appear, the
distribution point shall contain revocations for all reason codes.
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) and cACompromise (2) appear in one
distribution point, and the revocations with other reason codes
appear in another distribution point.
Where the issuingDistributionPoint extension contains a URL, the
following semantics MUST be assumed: the object is a pointer to the
most current CRL issued by this CA. The URI schemes ftp, http,
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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 }
5.2.6 Freshest CRL (a.k.a. Delta CRL Distribution Point)
The freshest CRL extension identifies how delta-CRL information for
this CRL is obtained. The extension MUST be non-critical.
The same syntax is used for this extension as the
cRLDistributionPoints certificate extension, and is described in
section 4.2.1.14. The same conventions apply to both extensions.
id-ce-freshestCRL OBJECT IDENTIFIER ::= { id-ce 46 }
FreshestCRL ::= CRLDistributionPoints
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
attributes 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
validation 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
subsections 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 SHOULD include reason
codes (see sec. 5.3.1) and invalidity dates (see sec. 5.3.3) whenever
this information is available.
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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;
however, 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 }
-- 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
applications that process this extension MUST 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
certificate. Conforming applications which encounter an id-
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holdinstruction-reject MUST 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
provides the date on which it is known or suspected that the private
key was compromised or that the certificate otherwise became invalid.
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 MUST be expressed
in Greenwich Mean Time (Zulu), and MUST 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 MUST always
be critical. If an implementation ignored this extension it could
not correctly attribute CRL entries to certificates. This
specification RECOMMENDS that implementations recognize this
extension.
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6 Certification Path Validation
Certification path validation procedures for the Internet PKI are
based on the algorithm supplied in [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 limited by constraints which are specified in the
certificates which comprise the path and inputs which are specified
by the relying party. 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
paths. Conforming implementations of this specification are not
required to implement this algorithm, but MUST provide functionality
equivalent to the external behavior 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. Valid paths
begin with certificates issued by a "most-trusted CA". The algorithm
requires the public key of the CA, the CA's name, and any constraints
upon the set of paths which may be validated using this key.
The selection of a "most-trusted CA" is a matter of policy: it could
be the top 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 validation procedure is the same regardless of the choice of
"most-trusted CA." In addition, different applications may rely on
different "most-trusted CA", or may accept paths that begin with any
of a set of "most-trusted CAs."
Section 6.2 describes methods for using the path validation algorithm
in specific implementations. 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.
Section 6.3 describes the steps necessary to determine if a
certificate is revoked or on hold status when CRLs are the revocation
mechanism used by the certificate issuer.
6.1 Basic Path Validation
This text describes an algorithm for X.509 path processing. A
conformant implementation MUST include an X.509 path processing
procedure that is functionally equivalent to the external behavior of
this algorithm. However, some of the certificate fields processed in
this algorithm are optional for compliant implementations. Clients
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that do not support these fields may omit the corresponding steps in
the path validation algorithm.
For example, clients are not required to support the policy mapping
extension. Clients that do not support this extension may omit the
path validation steps where policy mappings are processed. Note that
clients MUST reject the certificate if it contains critical
extensions that are not supported.
This text describes the trust anchor as an input to the algorithm.
There is no requirement that the same trust anchor be used to
validate all certification paths. Different trust anchors may be
used to validate different paths, as discussed further in Section
6.2.
The primary goal of path validation is to verify the binding between
a subject distinguished name or subject alternative name and subject
public key, as represented in the end entity certificate, based on
the public key of the trust anchor. This requires obtaining a
sequence of certificates that support that binding. The procedure
performed to obtain this sequence of certificates is outside the
scope of this section.
To meet this goal, the path validation process verifies, among other
things, that a prospective certification path (a sequence of n
certificates) satisfies the following conditions:
(a) for all x in {1, ..., n-1}, the subject of certificate x is
the issuer of certificate x+1;
(b) certificate 1 is issued by the trust anchor;
(c) certificate n is the end entity certificate; and
(d) for all x in {1, ..., n}, the certificate was valid at the
time in question.
A particular certification path may not, however, be appropriate for
all applications. The path validation process also determines the
set of certificate policies that are valid for this path, based on
the certificate policies extension, policy mapping extension, policy
constraints extension, and inhibit any-policy extension. To achieve
this, the path validation algorithm constructs a valid policy tree.
If the set of certificate policies that are valid for this path is
not empty, then the result will be a valid policy tree of depth n,
otherwise the result will be a NULL valid policy tree.
A certificate is termed self-issued if the DNs that appear in the
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subject and issuer fields are identical and are not empty. In
general, the issuer and subject of the certificates that make up a
path are different for each certificate. However, a CA may issue a
certificate to itself to support key rollover or changes in
certificate policies. These self-issued certificates are not counted
when evaluating path length or name constraints.
This section presents the algorithm in four basic steps: (1)
initialization, (2) basic certificate processing, (3) preparation for
the next certificate, and (4) wrap-up. Steps (1) and (4) are
performed exactly once. Step (2) is performed for all certificates
in the path. Step (3) is performed for all certificates in the path
except the final certificate. Figure 2 provides a high-level
flowchart of this algorithm.
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+-------+
| START |
+-------+
|
V
+----------------+
| Initialization |
+----------------+
|
+<--------------------+
| |
V |
+----------------+ |
| Process Cert | |
+----------------+ |
| |
V |
+================+ |
| IF Last Cert | |
| in Path | |
+================+ |
| | |
THEN | | ELSE |
V V |
+----------------+ +----------------+ |
| Wrap up | | Prepare for | |
+----------------+ | Next Cert | |
| +----------------+ |
V | |
+-------+ +--------------+
| STOP |
+-------+
Figure 2. Path Processing Flowchart
6.1.1 Inputs
This algorithm assumes the following seven inputs are provided to the
path processing logic:
(a) a prospective certification path of length n;
(b) 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.
(c) user-initial-policy-set: A set of certificate policy
identifiers naming the policies that are acceptable to the
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certificate user. The user-initial-policy-set contains the special
value any-policy if the user is not concerned about certificate
policy.
(d) trust anchor information, describing a CA that serves as a
trust anchor for the certification path. The trust anchor
information includes:
(1) the trusted issuer name,
(2) the trusted public key algorithm,
(3) the trusted public key, and
(4) optionally, the trusted public key parameters associated
with the public key.
The trust anchor information may be provided to the path
processing procedure in the form of a self-signed certificate. The
trusted anchor information is trusted because it was delivered to
the path processing procedure by some trustworthy out-of-band
procedure. If the trusted public key algorithm requires
parameters, then the parameters are provided along with the
trusted public key.
(e) initial-policy-mapping-inhibit, which indicates if policy
mapping is allowed in the certification path.
(f) initial-explicit-policy, which indicates if the path must be
valid for at least one of the certificate policies in the user-
initial-policy-set.
(g) initial-any-policy-inhibit, which indicates whether the any-
policy OID should be processed if it is included in a certificate.
6.1.2 Initialization
The initialization phase establishes eleven state variables based
upon the seven inputs:
(a) valid_policy_tree: A tree of certificate policies with their
optional qualifiers; each of the leaves of the tree represents a
valid policy at this stage in the certification path validation.
If valid policies exist at this stage in the certification path
validation, the depth of the tree is equal to the number of
certificates in the chain that have been processed. If valid
policies do not exist at this stage in the certification path
validation, the tree is set to NULL. Once the tree is set to NULL,
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policy processing ceases.
Each node in the valid_policy_tree includes four data objects: the
valid policy, a set of associated policy qualifiers, a set of one
or more expected policy values, and a criticality indicator. If
the node is at depth x, the components of the node have the
following semantics:
(1) The valid_policy is a single policy OID representing a
valid policy for the path of length x.
(2) The qualifier_set is a set of policy qualifiers associated
with the valid policy in certificate x.
(3) The criticality_indicator indicates whether the certificate
policy extension in certificate x was marked as critical.
(4) The expected_policy_set contains one or more policy OIDs
that would satisfy this policy in the certificate x+1.
The initial value of the valid_policy_tree is a single node with
valid_policy any-policy, an empty qualifier_set, an
expected_policy_set with the single value any-policy, and a
criticality_indicator of FALSE. This node is considered to be at
depth zero.
Figure 3 is a graphic representation of the initial state of the
valid_policy_tree. Additional figures will use this format to
describe changes in the valid_policy_tree during path processing.
+----------------+
| any-policy | <---- valid_policy
+----------------+
| {} | <---- qualifier_set
+----------------+
| FALSE | <---- criticality_indicator
+----------------+
| {any-policy} | <---- expected_policy_set
+----------------+
Figure 3. Initial value of the valid_policy_tree state variable
(b) permitted_subtrees: A set of root names for each name type
(e.g., X.500 distinguished names, email addresses, or ip
addresses) defining a set of subtrees within which all subject
names in subsequent certificates in the certification path shall
fall. This variable includes a set for each name type: the initial
value for the set for Distinguished Names is the set of all
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Distinguished names; the initial value for the set of RFC822 names
is the set of all RFC822 names, etc.
(c) excluded_subtrees: A set of root names for each name type
(e.g., X.500 distinguished names, email addresses, or ip
addresses) defining a set of subtrees within which no subject name
in subsequent certificates in the certification path may fall.
This variable includes a set for each name type, and the initial
value for each set is empty.
(d) explicit_policy: an integer which indicates if a non-NULL
valid_policy_tree is required. The integer indicates the number of
non-self-issued certificates to be processed before 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 a non-NULL valid_policy_tree, a later certificate can not
remove this requirement. If initial-explicit-policy is set, then
the initial value is 0, otherwise the initial value is n+1.
(e) inhibit_any-policy: an integer which indicates whether the
any-policy policy identifier is considered a match. The integer
indicates the number of non-self-issued certificates to be
processed before the any-policy OID, if asserted in a certificate,
is ignored. Once set, this variable may be decreased, but may not
be increased. That is, if a certificate in the path inhibits
processing of any-policy, a later certificate can not permit it.
If initial-any-policy-inhibit is set, then the initial value is 0,
otherwise the initial value is n+1.
(f) policy_mapping: an integer which indicates if policy mapping
is permitted. The integer indicates the number of non-self-issued
certificates to be processed before policy mapping is inhibited.
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 overridden by a later
certificate. If initial-policy-mapping-inhibit is set, then the
initial value is 0, otherwise the initial value is n+1.
(g) working_public_key_algorithm: the digital signature algorithm
used to verify the signature of a certificate. The
working_public_key_algorithm is initialized from the trusted
public key algorithm provided in the trust anchor information.
(h) working_public_key: the public key used to verify the
signature of a certificate. The working_public_key is initialized
from the trusted public key provided in the trust anchor
information.
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(i) working_public_key_parameters: parameters associated with the
current public key, that may required to verify a signature
(depending upon the algorithm). The working_public_key_parameters
variable is initialized from the trusted public key parameters
provided in the trust anchor information.
(j) working_issuer_name: the issuer distinguished name expected
in the next certificate in the chain. The working_issuer_name is
initialized to the trusted issuer provided in the trust anchor
information.
(k) max_path_length: this integer is initialized to n, and is
reset by the path length constraint field within the basic
constraints extension of a CA certificate.
Upon completion of the initialization steps, perform the basic
certificate processing steps specified in 6.1.3.
6.1.3 Basic Certificate Processing
The basic path processing actions to be performed for certificate i
are listed below.
(a) Verify the basic certificate information. The certificate
must satisfy each of the following:
(1) The certificate was signed with the
working_public_key_algorithm using the working_public_key and
the working_public_key_parameters.
(2) The certificate validity period includes time T.
(3) At time T, the certificate is not revoked and is not on
hold status. This may be determined by obtaining the
appropriate CRL (see section 6.3), status information, or by
out-of-band mechanisms.
(4) The certificate issuer name is the working_issuer_name.
(b) If certificate i is not self-issued, verify that the subject
name is within one of the permitted_subtrees for X.500
distinguished names, and verify that each of the alternative names
in the subjectAltName extension (critical or non-critical) is
within one of the permitted_subtrees for that name type.
(c) If certificate i is not self-issued, verify that the subject
name is not within one of the excluded_subtrees for X.500
distinguished names, and verify that each of the alternative names
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in the subjectAltName extension (critical or non-critical) is not
within one of the excluded_subtrees for that name type.
(d) If the certificate policies extension is present in the
certificiate and the valid_policy_tree is not NULL, process the
policy information by performing the following steps in order:
(1) For each policy P not equal to any-policy in the
certificate policies extension, let P-OID denote the OID in
policy P and P-Q denote the qualifier set for policy P.
Perform the following steps in order:
(i) If the valid_policy_tree includes a node of depth i-1
where P-OID is in the expected_policy_set, create a child
node as follows: set the valid_policy to OID- P; set the
qualifier_set to P-Q, and set the expected_policy_set to
{P-OID}.
For example, consider a valid_policy_tree with a node of
depth i-1 where the expected_policy_set is {Gold, White}.
Assume the certificate policies Gold and Silver appear in
the certificate policies extension of certificate i. The
Gold policy is matched but the Silver policy is not. This
rule will generate a child node of depth i for the Gold
policy. The result is shown as Figure 4.
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|-----------------|
| Red |
|-----------------|
| {} |
|-----------------| node of depth i-1
| FALSE |
|-----------------|
| {Gold, White} |
|-----------------|
|
|
|
V
|-----------------|
| Gold |
|-----------------|
| {} |
|-----------------| node of depth i
| uninitialized |
|-----------------|
| {Gold} |
|-----------------|
Figure 4. Processing an exact match
(ii) If there was no match in step (i) and the
valid_policy_tree includes a node of depth i-1 with the
valid policy any-policy, generate a child node with the
following values: set the valid_policy to P-OID; set the
qualifier_set to P-Q, and set the expected_policy_set to
{P-OID}.
For example, consider a valid_policy_tree with a node of
depth i-1 where the valid_policy is any-policy. Assume the
certificate policies Gold and Silver appear in the
certificate policies extension of certificate i. The Gold
policy does not have a qualifier, but the Silver policy has
the qualifier Q-Silver. If Gold and Silver were not matched
in (i) above, this rule will generate two child nodes of
depth i, one for each policy. The result is shown as Figure
5.
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|-----------------|
| any-policy |
|-----------------|
| {} |
|-----------------| node of depth i-1
| FALSE |
|-----------------|
| {any-policy} |
|-----------------|
/ \
/ \
/ \
/ \
|-----------------| |-----------------|
| Gold | | Silver |
|-----------------| |-----------------|
| {} | | {Q-Silver} |
|-----------------| nodes of |-----------------|
| uninitialized | depth i | uninitialized |
|-----------------| |-----------------|
| {Gold} | | {Silver} |
|-----------------| |-----------------|
Figure 5. Processing unmatched policies when a leaf node
specifies any-policy
(2) If the certificate policies extension includes the policy
any-policy with the qualifier set AP-Q and inhibit_any-policy
is greater than 0, then:
For each node in the valid_policy_tree of depth i-1, for each
value in the expected_policy_set (including any-policy) that
does not appear in a child node, create a child node with the
following values: set the valid_policy to the value from the
expected_policy_set in the parent node; set the qualifier_set
to AP-Q, and set the expected_policy_set to the value in the
valid_policy from this node.
For example, consider a valid_policy_tree with a node of depth
i-1 where the expected_policy_set = {Gold, Silver}. Assume
any-policy appears in the certificate policies extension of
certificate i, but Gold and Silver do not. This rule will
generate two child nodes of depth i, one for each policy. The
result is shown below as Figure 6.
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|-----------------|
| Red |
|-----------------|
| {} |
|-----------------| node of depth i-1
| FALSE |
|-----------------|
| {Gold, Silver} |
|-----------------|
/ \
/ \
/ \
/ \
|-----------------| |-----------------|
| Gold | | Silver |
|-----------------| |-----------------|
| {} | | {} |
|-----------------| nodes of |-----------------|
| uninitialized | depth i | uninitialized |
|-----------------| |-----------------|
| {Gold} | | {Silver} |
|-----------------| |-----------------|
Figure 6. Processing unmatched policies when the certificate
policies extension specifies any-policy
(3) If there is a node in the valid_policy_tree of depth i-1 or
less without any child nodes, delete that node. Repeat this
step until there are no nodes of depth i-1 or less without
children.
For example, consider the valid_policy_tree shown in Figure 7
below. The two nodes at depth i-1 that are marked with an to
the resulting tree will cause the node at depth i-2 that is
marked with an 'Y' to be deleted. The following application of
the rule does not cause any nodes to be deleted, and this step
is complete.
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+-----------+
| | node of depth i-3
+-----------+
/ | \
/ | \
/ | \
+-----------+ +-----------+ +-----------+
| | | | | Y | nodes of
+-----------+ +-----------+ +-----------+ depth i-2
/ \ || ||
/ \ || ||
/ \ || ||
+-----------+ +-----------+ +-----------+ +-----------+ nodes of
| | | X | | | | X | depth
+-----------+ +-----------+ +-----------+ +-----------+ i-1
| / | \
| / | \
| / | \
+-----------+ +-----------+ +-----------+ +-----------+ nodes of
| | | | | | | | depth
+-----------+ +-----------+ +-----------+ +-----------+ i
Figure 7. Pruning the valid_policy_tree
(4) If the certificate policies extension was marked as
critical, set the criticality_indicator in all nodes of depth i
to TRUE. If the certificate policies extension was not marked
critical, set the criticality_indicator in all nodes of depth i
to FALSE.
(e) If the certificate policies extension is not present, set the
valid_policy_tree to NULL.
(f) verify that either explicit_policy is greater than 0 or the
valid_policy_tree is not equal to NULL;
If any of steps (a), (b), (c), or (f) fails, the procedure
terminates, returning a failure indication and an appropriate reason.
If i is not equal to n, continue by performing the preparatory steps
listed in 6.1.4. If i is equal to n, perform the wrap-up steps
listed in 6.1.5.
6.1.4 Preparation for Certificate i+1
To prepare for processing of certificate i+1, perform the following
steps for certificate i:
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(a) If a policy mapping extension is present, verify that the
special value any-policy does not appear as an issuerDomainPolicy
or a subjectDomainPolicy.
(b) If a policy mapping extension is present, then for each
issuerDomainPolicy ID-P in the policy mapping extension:
(1) If the policy_mapping variable is greater than 0, for each
node in the valid_policy_tree of depth i where ID-P is the
valid_policy, set expected_policy_set to the set of
subjectDomainPolicy values that are specified as equivalent to
ID-P by the policy mapping extension.
If no node of depth i in the valid_policy_tree has a
valid_policy of ID-P but there is a node of depth i with a
valid_policy of any-policy, then generate a child node of the
node of depth i-1 that has a valid_policy of any-policy as
follows:
(i) set the valid_policy to ID-P;
(ii) set the qualifier_set to the qualifier set of the
policy any-policy in the certificate policies extension of
certificate i;
(iii) set the criticality_indicator to the criticality of
the certificate policies extension of certificate i;
(iv) and set the expected_policy_set to the set of
subjectDomainPolicy values that are specified as equivalent
to ID-P by the policy mappings extension.
(2) If the policy_mapping variable is equal to 0:
(i) delete each node of depth i in the valid_policy_tree
where ID-P is the valid_policy.
(ii) If there is a node in the valid_policy_tree of depth
i-1 or less without any child nodes, delete that node.
Repeat this step until there are no nodes of depth i-1 or
less without children.
(c) Assign the certificate subject name to working_issuer_name.
(d) Assign the certificate subjectPublicKey to working_public_key.
(e) If the subjectPublicKeyInfo field of the certificate contains
an algorithm field with non-null parameters, assign the parameters
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to the working_public_key_parameters variable.
If the subjectPublicKeyInfo field of the certificate contains an
algorithm field with null parameters or parameters are omitted,
compare the certificate subjectPublicKey algorithm to the
working_public_key_algorithm. If the certificate subjectPublicKey
algorithm and the working_public_key_algorithm are different, set
the working_public_key_parameters to null.
(f) Assign the certificate subjectPublicKey algorithm to the
working_public_key_algorithm variable.
(g) If a name constraints extension is included in the
certificate, modify the permitted_subtrees and excluded_subtrees
state variables as follows:
(1) If permittedSubtrees is present in the certificate, set the
permitted_subtrees state variable to the intersection of its
previous value and the value indicated in the extension field.
If permittedSubtrees does not include a particular name type,
the permitted_subtrees state variable is unchanged for that
name type.
(2) 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. If
excludedSubtrees does not include a particular name type, the
excluded_subtrees state variable is unchanged for that name
type.
(h) If the issuer and subject names are not identical:
(1) If explicit_policy is not 0, decrement explicit_policy by
1.
(2) If policy_mapping is not 0, decrement policy_mapping by 1.
(3) If inhibit_any-policy is not 0, decrement inhibit_any-
policy by 1.
(i) If a policy constraints extension is included in the
certificate, modify the explicit_policy and policy_mapping state
variables as follows:
(1) If requireExplicitPolicy is present and is less than
explicit_policy, set explicit_policy to the value of
requireExplicitPolicy.
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(2) If inhibitPolicyMapping is present and is less than
policy_mapping, set policy_mapping to the value of
inhibitPolicyMapping.
(j) If the inhibitAnyPolicy extension is included in the
certificate and is less than inhibit_any-policy, set inhibit_any-
policy to the value of inhibitAnyPolicy.
(k) Verify that the certificate is a CA certificate (as specified
in a basicConstraints extension or as verified out-of-band).
(l) If the certificate was not self-issued, verify that
max_path_length is greater than zero and decrement max_path_length
by 1.
(m) If pathLengthConstraint is present in the certificate and is
less than max_path_length, set max_path_length to the value of
pathLengthConstraint.
(n) If a key usage extension is present and marked critical,
verify that the keyCertSign bit is set.
(o) Recognize and process any other critical extension present in
the certificate.
If check (a), (k), (l), (n) or (o) fails, the procedure terminates,
returning a failure indication and an appropriate reason.
If (a), (k), (l), (n) and (o) have completed successfully, increment
i and perform the basic certificate processing specified in 6.1.2.
6.1.5 Wrap-up procedure
To complete the processing of the end entity certificate, perform the
following steps for certificate n:
(a) If certificate n was not self-issued and explicit_policy is
not 0, decrement explicit_policy by 1.
(b) If a policy constraints extension is included in the
certificate and requireExplicitPolicy is present and has a value
of 0, set the explicit_policy state variable to 0.
(c) Assign the certificate subjectPublicKey to working_public_key.
(d) If the subjectPublicKeyInfo field of the certificate contains
an algorithm field with non-null parameters, assign the parameters
to the working_public_key_parameters variable.
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If the subjectPublicKeyInfo field of the certificate contains an
algorithm field with null parameters or parameters are omitted,
compare the certificate subjectPublicKey algorithm to the
working_public_key_algorithm. If the certificate subjectPublicKey
algorithm and the working_public_key_algorithm are different, set
the working_public_key_parameters to null.
(e) Assign the certificate subjectPublicKey algorithm to the
working_public_key_algorithm variable.
(f) Recognize and process any other critical extension present in
the certificate n.
(g) Calculate the intersection of the valid_policy_tree and the
user-initial-policy-set, as follows:
(i) If the valid_policy_tree is NULL, the intersection is NULL.
(ii) If the valid_policy_tree is not NULL and the user-
initial-policy-set is any-policy, the intersection is the
entire valid_policy_tree.
(iii) If the valid_policy_tree is not NULL and the user-
initial-policy-set is not any-policy, calculate the
intersection of the valid_policy_tree and the user-initial-
policy-set as follows:
1. Determine the set of policy nodes whose parent nodes have
a valid_policy of any-policy. This is the
valid_policy_node_set.
2. If the valid_policy of any node in the
valid_policy_node_set is not in the user-initial-policy-set
and is not any-policy, delete this node and all its
children.
3. If there is a node in the valid_policy_tree of depth n-1
or less without any child nodes, delete that node. Repeat
this step until there are no nodes of depth n-1 or less
without children.
(h) If the certificate was not self-issued, verify that
max_path_length is greater than zero and decrement
max_path_length by 1.
If check (h) fails, the procedure terminates, returning a failure
indication and an appropriate reason.
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If check (h) succeeds and either (1) value of explicit_policy
variable is greater than zero, or (2) the valid_policy_tree is not
NULL, then path processing has succeeded.
6.1.6 Outputs
If path processing succeeds, the procedure terminates, returning a
success indication together with final value of the
valid_policy_tree, the working_public_key, the
working_public_key_algorithm, and the working_public_key_parameters.
6.2 Using the Path Validation Algorithm
The path validation algorithm describes the process of validating a
single certification path. While each path begins with a specific
trust anchor, there is no requirement that all paths validated by a
particular system share a single trust anchor.
The selection of one or more trusted CAs is a local decision. A
system may provide any one of its trusted CAs as the trust anchor for
a particular path. The inputs to the path validation algorithm may
be different for each path. The inputs used to process a path may
reflect application-specific requirements or limitations in the trust
accorded a particular trust anchor. For example, a trusted CA may
only be trusted for a particular certificate policy. This
restriction can be expressed through the inputs to the path
validation procedure.
It is also possible to specify an extended version of the above
certification path processing procedure which results in default
behavior 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
SubordinateToCA 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.
6.3 CRL Validation
This section describes the steps necessary to determine if a
certificate is revoked or on hold status when CRLs are the revocation
mechanism used by the certificate issuer. Conforming implementations
of this specification are not required to implement this algorithm,
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but MUST be functionally equivalent to the external behavior
resulting from this procedure. Any algorithm may be used by a
particular implementation so long as it derives the correct result.
This algorithm defines a set of inputs, a set of state variables, and
processing steps that are performed for each certificate in the path.
6.3.1 Revocation Inputs
To support revocation processing, the algorithm requires two inputs:
(a) certificate: the algorithm requires the certificate serial
number and issuer name to determine if a certificate is on a
particular CRL. The basicConstraints extension is used to
determine whether the supplied certificate is associated with a CA
or an end-entity. If present, the algorithm may use the
cRLDistributionsPoint and freshestCRL extensions to determine
revocation status.
(b) use-deltas: This boolean input determines if the delta needs
to be checked if the CRL is still valid.
Note that implementations supporting legacy PKIs, such as RFC 1422
and X.509 version 1, will need an additional input indicating
whether the supplied certificate is associated with a CA or an
end-entity.
6.3.2 Initialization and Revocation State Variables
To support CRL processing, the algorithm requires the following state
variables:
(a) reasons_mask: This variable contains the set of revocation
reasons supported by the CRLs and delta CRLs processed so far. The
legal members of the set are the possible values for reasonflags:
unspecified; keyCompromise; caCompromise; affiliationChanged;
superseded; cessationOfOperation; and certificateHold. The
special value all-reasons is used to denote the set of all legal
members. This variable is initialized to the empty set.
(b) cert_status: This variable contains the status of the
certificate. Legal values are unspecified; keyCompromise;
caCompromise; affiliationChanged; superseded;
cessationOfOperation; and certificateHold, the special value
UNREVOKED, or the special value UNDETERMINED. This variable is
initialized to the special value UNREVOKED.
(c) interim_reasons_mask: This contains the set of revocation
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reasons supported by the CRL or delta CRL currently being
processed.
Note: In some environments, it is not necessary to check all reason
codes. For example, some envornments only are concerned with
caCompromise and keyCompromise for CA certificates. This algorithnm
checks all reason codes. Additional processing and state variables
may be necessary to limit the checking to a subset of the reason
codes.
6.3.3 CRL Processing
This algorithm begins by assuming the certificate is not revoked.
The algorithm checks one or more CRLs until either the certificate
status is determined to be revoked or sufficent CRLs have been
checked to cover all reason codes.
For each distribution point (DP) in the crl distribution points
extension while ((reasons_mask is not all-reasons) and (cert_status
is UNREVOKED))
(1) locate the corresponding CRL in CRL cache, and perform the
following verifications:
(a) compute the interim_reasons_mask for this CRL as follows:
1. if the CRL includes reasons and the DP includes reasons,
then set interim_reasons_mask to the intersection of of
reasons in the DP and reasons in CRL reasons extension.
2. if the CRL includes reasons but the DP omits reasons,
then set interim_reasons_mask to the value of CRL reasons.
3. if the CRL omits reasons but the DP includes reasons,
then set interim_reasons_mask to the value of DP reasons.
4. if the CRL omits reasons and the DP omits reasons, then
set interim_reasons_mask to the special value all-reasons.
Verify that interim_reasons_mask includes one or more reasons
that is not included in the reasons_mask.
(b) Verify the issuer of the CRL as follows:
if the DP includes cRLIssuer, then verify that the CRL
issuer matches cRLIssuer else verify that the CRL issuer
matches the certificate issuer.
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(c) obtain and validate the certification path for the CRL
issuer.
(d) validate the signature on the CRL.
(2) If each of the verifications (a) through (d) succeeds, then
perform the following steps:
(a) If the value of next update field is before the current-
time, otain an appropriate delta CRL or discard the CRL.
(b) If the user wants freshest available info AND the freshest
CRL extension is present, check for a corresponding delta for
this base.
(c) If a delta was obtained in (a) or (b), verify that the
delta CRL addresses the same set of certificates and the same
set of reasons as the CRL.
(d) Perform the checks in step 1 (b) and (c):
1. obtain and validate the certification path for the delta
issuer
2. validate the signature on the delta CRL
(e) If a delta CRL was obtained in (a) or (b), and the
verifications (c) and (d) suceeded, combine the base and
delta to form a complete CRL.
(3) If steps and (1) and (2) succeed, then set reasons_mask to the
union of reasons_mask and interim_reasons_mask
(4) Search for the certificate on the CRL
(a) search for the serial number on the CRL
(b) if (a) succeeds, verify that (1) the CRL entry extension
Certificate issuer is not present or (2) the issuer identified
in the CRL entry extension Certificate issuer is the issuer of
the certificate.
(c) if (a) and (b) succeeded, set the cert_status variable as
appropriate:
1. if the reasons extension is present, set the cert_status
variable to the value of the reasons extension
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2. if the reasons extension is not present, set the
cert_status variable to the special value not-specified.
if ((reasons_mask is all-reasons) OR (if cert_status is not
UNREVOKED) return cert_status
If all CRLs named in the crl distribution points extension have
been exhausted, and the reasons_mask is not all-reasons and the
cert_status is still UNREVOKED, the verifier must obtain
additional CRLs.
The verifier must repeat the process above with the additional
CRLs not specified in a distribution point.
If all CRLs are exhausted and the reasons_mask is not all-reasons
return the cert_status UNDETERMINED.
7 References
[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
facilities", November 1987.
[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 1510] Kohl, J., and C. Neuman, "The Kerberos Network
Authentication Service (V5)," RFC 1510, September 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 1738] Berners-Lee, T., Masinter L., and M. McCahill.
"Uniform Resource Locators (URL)", RFC 1738, December 1994.
[RFC 1778] Howes, T., Kille S., Yeong, W. and C. Robbins. "The
String Representation of Standard Attribute Syntaxes,"
RFC 1778, March 1995.
Housley, Ford, Polk, & Solo [Page 79]
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[RFC 1883] S. Deering and R. Hinden. "Internet Protocol, Version 6
(IPv6) Specification", December 1995.
[RFC 2119] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[RFC 2247] Kille, S., Wahl, M., Grimstad, A., Huber, R. and S.
Sataluri. "Using Domains in LDAP/X.500 Distinguished Names",
RFC 2247, January 1998.
[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.
[RFC 2560] Myers, M., Ankney R., Malpani A., Galperin S., and
C. Adams, "Online Certificate Status Protocal - OCSP",
June 1999.
[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.501] ITU-T Recommendation X.501: Information
Technology - Open Systems Interconnection - The
Directory: Models, 1993.
[X.509] ITU-T Recommendation X.509 (1997 E): Information
Technology - Open Systems Interconnection - The
Directory: Authentication Framework, June 1997.
[X.520] ITU-T Recommendation X.520: Information
Technology - Open Systems Interconnection - The
Directory: Selected Attribute Types, 1993.
[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.
[PKINIT] Tung, B., Neuman C., Hur M., Medvinsky A., Medvinsky S.,
Wray J., and J. Trostle, "Public Key Cryptography for
Initial Authentciaion in Kerberos,"
draft-ietf-cat-kerberos-pk-init-11.txt, March 15, 2000.
[PKIX ALGS] Bassham, L., Housley, R., and W. Polk, "Internet X.509
Housley, Ford, Polk, & Solo [Page 80]
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Public Key Infrastructure Representation of Public Keys
and Digital Signatures,"
draft-ietf-pkix-ipki-pkalgs-00.txt, July 14, 2000.
[PKIX TSA] Cain, P., Pinkas, D., and R. Zuccherato, "Internet X.509
Public Key Infrastructure Time Stamp Protocol,"
draft-ietf-pkix-time-stamp-12.txt, November, 2000.
8 Intellectual Property Rights
The IETF has been notified of intellectual property rights claimed in
regard to some or all of the specification contained in this
document. For more information consult the online list of claimed
rights.
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
9 Security Considerations
The majority of this specification is devoted to the format and
content of certificates and CRLs. Since certificates and CRLs are
digitally 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
implications.
However, security factors outside the scope of this specification
will affect the assurance provided to certificate users. This
section highlights critical issues that should be considered by
implementors, 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.
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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
applications (e.g., SSL) use a single key pair for signature and key
management.
The protection afforded private keys is a critical factor in
maintaining security. On a small scale, failure of users to protect
their private keys will permit an attacker to masquerade as them, or
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 shall be revoked,
preventing 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 procedures (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
avoiding 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.
Similarly, 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
distribution of trusted CA public keys (usually in the form of a
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"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
algorithm described in section 6 relies upon the integrity of the
trusted CA information, and especially the integrity of the public
keys associated with the trusted CAs. By substituting public keys
for which an attacker has the private key, an attacker could trick
the user into accepting false certificates.
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 algorithms
will limit the utility of a certificate. CAs are encouraged to note
advances in cryptology so they can employ strong cryptographic
techniques. In addition, CAs should decline to issue certificates to
CAs or end entities that generate weak signatures.
Inconsistent application of name comparison rules may result in
acceptance of invalid X.509 certification paths, or rejection of
valid ones. The X.500 series of specifications defines rules for
comparing distinguished names require comparison of strings without
regard to case, character set, multi-character white space substring,
or leading and trailing white space. This specification relaxes
these requirements, requiring support for binary comparison at a
minimum.
CAs shall encode the distinguished name in the subject field of a CA
certificate identically to the distinguished name in the issuer field
in certificates issued by the latter CA. If CAs use different
encodings, implementations of this specification may fail to
recognize name chains for paths that include this certificate. As a
consequence, valid paths could be rejected.
In addition, name constraints for distinguished names shall be stated
identically to the encoding used in the subject field or
subjectAltName extension. If not, (1) name constraints stated as
excludedSubTrees will not match and invalid paths will be accepted
and (2) name constraints expressed as permittedSubtrees will not
match and valid paths will be rejected. To avoid acceptance of
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invalid paths, CAs should state name constraints for distinguished
names as permittedSubtrees where ever possible.
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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, 1988 Syntax
PKIX1Explicit88 {iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-explicit(18)}
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 2279.
--
-- PKIX specific OIDs
id-pkix OBJECT IDENTIFIER ::=
{ iso(1) identified-organization(3) dod(6) internet(1)
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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
-- access descriptor definitions
id-ad-ocsp OBJECT IDENTIFIER ::= { id-ad 1 }
id-ad-caIssuers OBJECT IDENTIFIER ::= { id-ad 2 }
id-ad-timeStamping OBJECT IDENTIFIER ::= { id-ad 3 }
id-ad-caRepository OBJECT IDENTIFIER ::= { id-ad 5 }
-- 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
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--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}
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)),
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utf8String UTF8String (SIZE (1..ub-state-name)),
bmpString BMPString (SIZE(1..ub-state-name)) }
--
id-at-organizationName AttributeType ::= {id-at 10}
X520OrganizationName ::= CHOICE {
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
id-at-serialNumber AttributeType ::= { id-at 5 }
X520SerialNumber ::= PrintableString (SIZE (1..ub-serial-number))
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-- domaincomponent and identifier from RFC 2247
id-domainComponent OBJECT IDENTIFIER ::=
{ 0 9 2342 19200300 100 1 25 }
DomainComponent ::= IA5String
-- 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))
-- 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,
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issuer Name,
validity Validity,
subject Name,
subjectPublicKeyInfo SubjectPublicKeyInfo,
issuerUniqueID [1] IMPLICIT UniqueIdentifier OPTIONAL,
-- If present, version shall be v2 or v3
subjectUniqueID [2] IMPLICIT UniqueIdentifier OPTIONAL,
-- If present, version shall be v2 or v3
extensions [3] Extensions OPTIONAL
-- If present, version shall 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
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, shall be v2
signature AlgorithmIdentifier,
issuer Name,
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thisUpdate Time,
nextUpdate Time OPTIONAL,
revokedCertificates SEQUENCE OF SEQUENCE {
userCertificate CertificateSerialNumber,
revocationDate Time,
crlEntryExtensions Extensions OPTIONAL
-- if present, shall be v2
} OPTIONAL,
crlExtensions [0] Extensions OPTIONAL
-- if present, shall be v2 -- }
-- Version, Time, CertificateSerialNumber, and Extensions were
-- defined earlier for use in the certificate structure
AlgorithmIdentifier ::= SEQUENCE {
algorithm OBJECT IDENTIFIER,
parameters ANY DEFINED BY algorithm OPTIONAL }
-- contains a value of the type
-- registered for use with the
-- algorithm object identifier value
-- x400 address syntax starts here
-- 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,
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-- 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)),
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
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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
--
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
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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)),
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
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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
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
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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
(SIZE (1..ub-domain-defined-attribute-value-length)) }
-- specifications of Upper Bounds shall 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-serialNumber 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
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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
-- 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
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A.2 Implicitly Tagged Module, 1988 Syntax
PKIX1Implicit88 {iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0) id-pkix1-implicit(19)}
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
-- EXPORTS ALL --
IMPORTS
id-pkix, id-pe, id-qt, id-kp, id-qt-unotice, id-qt-cps,
id-ad, id-ad-ocsp, id-ad-caIssuers,
-- delete following line if "new" types are supported --
BMPString, UniversalString, UTF8String, -- end "new" types
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 shall 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
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-- key usage extension OID and syntax
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) }
-- 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 shall be present
-- certificate policies extension OID and syntax
id-ce-certificatePolicies OBJECT IDENTIFIER ::= { id-ce 32 }
anyPolicy OBJECT IDENTIFIER ::= {id-ce-certificatePolicies 0}
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 shall
-- augment the following definition for PolicyQualifierId
PolicyQualifierId ::=
OBJECT IDENTIFIER ( id-qt-cps | id-qt-unotice )
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-- CPS pointer qualifier
CPSuri ::= IA5String
-- user notice qualifier
UserNotice ::= SEQUENCE {
noticeRef NoticeReference OPTIONAL,
explicitText DisplayText OPTIONAL}
NoticeReference ::= SEQUENCE {
organization DisplayText,
noticeNumbers SEQUENCE OF INTEGER }
DisplayText ::= CHOICE {
ia5String IA5String (SIZE (1..200)),
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
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-- 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 }
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 }
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PolicyConstraints ::= SEQUENCE {
requireExplicitPolicy [0] SkipCerts OPTIONAL,
inhibitPolicyMapping [1] SkipCerts OPTIONAL }
SkipCerts ::= INTEGER (0..MAX)
-- CRL distribution points extension OID and syntax
id-ce-cRLDistributionPoints OBJECT IDENTIFIER ::= {id-ce 31}
CRLDistributionPoints ::= 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 }
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-- inhibit any policy OID and syntax
id-ce-inhibitAnyPolicy OBJECT IDENTIFIER ::= { id-ce 54 }
InhibitAnyPolicy ::= SkipCerts
-- freshest (delta-)CRL extension OID and syntax
id-ce-freshestCRL OBJECT IDENTIFIER ::= { id-ce 46 }
FreshestCRL ::= CRLDistributionPoints
-- authority info access
id-pe-authorityInfoAccess OBJECT IDENTIFIER ::= { id-pe 1 }
AuthorityInfoAccessSyntax ::=
SEQUENCE SIZE (1..MAX) OF AccessDescription
AccessDescription ::= SEQUENCE {
accessMethod OBJECT IDENTIFIER,
accessLocation GeneralName }
-- CRL number extension OID and syntax
id-ce-cRLNumber OBJECT IDENTIFIER ::= { id-ce 20 }
CRLNumber ::= INTEGER (0..MAX)
-- 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
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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 ::=
{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}
-- invalidity date CRL entry extension OID and syntax
id-ce-invalidityDate OBJECT IDENTIFIER ::= { id-ce 24 }
InvalidityDate ::= GeneralizedTime
END
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Appendix B. ASN.1 Notes
CAs MUST force the serialNumber to be a non-negative integer, that
is, the sign bit in the DER encoding of the INTEGER value MUST be
zero - this can be done by adding a leading (leftmost) `00'H octet if
necessary. This removes a potential ambiguity in mapping between a
string of octets and an integer value.
As noted in section 4.1.2.2, serial numbers can be expected to
contain long integers. Certificate users MUST be able to handle
serialNumber values up to 20 octets in length. Conformant CAs MUST
NOT use serialNumber values longer than 20 octets.
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.
Implementations 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
PrintableString. 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
characters allowed by ISO 10646-1. ISO 10646 is the Universal
multiple-octet coded Character Set (UCS). ISO 10646-1 specifes the
architecture 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
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 ISO
10646." ISO is expected to formally add UTF8String to the list of
choices for DirectoryString in 1998 as well.
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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
DirectoryString and the CPS qualifier extensions.
Implementers should note that the DER encoding of the SET OF values
requires ordering of the encodings of the values. In particular, this
issue arises with respect to distinguished names.
Object Identifiers (OIDs) are used throught this specification to
identify certificate policies, public key and signature algorithms,
certificate extensions, etc. There is no maximum size for OIDs.
This specification mandates support for OIDs which have arc elements
with values that are less than 2^28, i.e. they MUST be between 0 and
268,435,455 inclusive. This allows each arc element to be represented
within a single 32 bit word. Implementations MUST also support OIDs
where the length of the dotted decimal (see [LDAP], section 4.1.2)
string representation can be up to 100 bytes (inclusive).
Implementations MUST be able to handle OIDs with up to 20 elements
(inclusive). CAs SHOULD NOT issue certificates which contain OIDs
that breach these requirements.
Appendix C. Examples
This section contains four examples: three certificates and a CRL.
The first two certificates and the CRL comprise a minimal
certification path.
Section C.1 contains an annotated hex dump of a "self-signed"
certificate 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.
Section C.2 contains an annotated hex dump of an end-entity
certificate. The end entity certificate contains a DSA public key,
and is signed by the private key corresponding to the "self-signed"
certificate in section C.1.
Section C.3 contains a dump of an end entity certificate which
contains an RSA public key and is signed with RSA and MD5. This
certificate is not part of the minimal certification path.
Section C.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 certificates includes the end entity certificate
presented in C.2.
The certificates were processed using Peter Gutman's dumpasn1 utility
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to generate the output. The source for the dumpasn1 utility is
available at <http://www.cs.auckland.ac.nz/~pgut001/dumpasn1.c>. The
binaries for the certificates and CRLs are available at
<http://csrc.nist.gov/pki/pkixtools>.
C.1 Certificate
This section contains an annotated hex dump of a 699 byte version 3
certificate. The certificate contains the following information:
(a) the serial number is 23 (17 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 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
parameters;
(g) the certificate contains a subject key identifier extension; and
(h) the certificate is a CA certificate (as indicated through the
basic constraints extension.)
0 30 701: SEQUENCE {
4 30 637: SEQUENCE {
8 A0 3: [0] {
10 02 1: INTEGER 2
: }
13 02 1: INTEGER 23
16 30 9: SEQUENCE {
18 06 7: OBJECT IDENTIFIER dsaWithSha1 (1 2 840 10040 4 3)
: }
27 30 42: SEQUENCE {
29 31 11: SET {
31 30 9: SEQUENCE {
33 06 3: OBJECT IDENTIFIER countryName (2 5 4 6)
38 13 2: PrintableString 'US'
: }
: }
42 31 12: SET {
44 30 10: SEQUENCE {
46 06 3: OBJECT IDENTIFIER organizationName (2 5 4 10)
51 13 3: PrintableString 'gov'
: }
: }
56 31 13: SET {
58 30 11: SEQUENCE {
60 06 3: OBJECT IDENTIFIER
organizationalUnitName (2 5 4 11)
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65 13 4: PrintableString 'NIST'
: }
: }
: }
71 30 30: SEQUENCE {
73 17 13: UTCTime '970630000000Z'
88 17 13: UTCTime '971231000000Z'
: }
103 30 42: SEQUENCE {
105 31 11: SET {
107 30 9: SEQUENCE {
109 06 3: OBJECT IDENTIFIER countryName (2 5 4 6)
114 13 2: PrintableString 'US'
: }
: }
118 31 12: SET {
120 30 10: SEQUENCE {
122 06 3: OBJECT IDENTIFIER organizationName (2 5 4 10)
127 13 3: PrintableString 'gov'
: }
: }
132 31 13: SET {
134 30 11: SEQUENCE {
136 06 3: OBJECT IDENTIFIER
organizationalUnitName (2 5 4 11)
141 13 4: PrintableString 'NIST'
: }
: }
: }
147 30 440: SEQUENCE {
151 30 300: SEQUENCE {
155 06 7: OBJECT IDENTIFIER dsa (1 2 840 10040 4 1)
164 30 287: SEQUENCE {
168 02 129: INTEGER
: 00 B6 8B 0F 94 2B 9A CE A5 25 C6 F2 ED FC FB 95
: 32 AC 01 12 33 B9 E0 1C AD 90 9B BC 48 54 9E F3
: 94 77 3C 2C 71 35 55 E6 FE 4F 22 CB D5 D8 3E 89
: 93 33 4D FC BD 4F 41 64 3E A2 98 70 EC 31 B4 50
: DE EB F1 98 28 0A C9 3E 44 B3 FD 22 97 96 83 D0
: 18 A3 E3 BD 35 5B FF EE A3 21 72 6A 7B 96 DA B9
: 3F 1E 5A 90 AF 24 D6 20 F0 0D 21 A7 D4 02 B9 1A
: FC AC 21 FB 9E 94 9E 4B 42 45 9E 6A B2 48 63 FE
: 43
300 02 21: INTEGER
: 00 B2 0D B0 B1 01 DF 0C 66 24 FC 13 92 BA 55 F7
: 7D 57 74 81 E5
323 02 129: INTEGER
: 00 9A BF 46 B1 F5 3F 44 3D C9 A5 65 FB 91 C0 8E
Housley, Ford, Polk, & Solo [Page 108]
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: 47 F1 0A C3 01 47 C2 44 42 36 A9 92 81 DE 57 C5
: E0 68 86 58 00 7B 1F F9 9B 77 A1 C5 10 A5 80 91
: 78 51 51 3C F6 FC FC CC 46 C6 81 78 92 84 3D F4
: 93 3D 0C 38 7E 1A 5B 99 4E AB 14 64 F6 0C 21 22
: 4E 28 08 9C 92 B9 66 9F 40 E8 95 F6 D5 31 2A EF
: 39 A2 62 C7 B2 6D 9E 58 C4 3A A8 11 81 84 6D AF
: F8 B4 19 B4 C2 11 AE D0 22 3B AA 20 7F EE 1E 57
: 18
: }
: }
455 03 133: BIT STRING 0 unused bits
: 02 81 81 00 B5 9E 1F 49 04 47 D1 DB F5 3A DD CA
: 04 75 E8 DD 75 F6 9B 8A B1 97 D6 59 69 82 D3 03
: 4D FD 3B 36 5F 4A F2 D1 4E C1 07 F5 D1 2A D3 78
: 77 63 56 EA 96 61 4D 42 0B 7A 1D FB AB 91 A4 CE
: DE EF 77 C8 E5 EF 20 AE A6 28 48 AF BE 69 C3 6A
: A5 30 F2 C2 B9 D9 82 2B 7D D9 C4 84 1F DE 0D E8
: 54 D7 1B 99 2E B3 D0 88 F6 D6 63 9B A7 E2 0E 82
: D4 3B 8A 68 1B 06 56 31 59 0B 49 EB 99 A5 D5 81
: 41 7B C9 55
: }
591 A3 52: [3] {
593 30 50: SEQUENCE {
595 30 31: SEQUENCE {
597 06 3: OBJECT IDENTIFIER
subjectKeyIdentifier (2 5 29 14)
602 04 24: OCTET STRING
: 04 16 04 14 E7 26 C5 54 CD 5B A3 6F 35 68 95 AA
: D5 FF 1C 21 E4 22 75 D6
: }
628 30 15: SEQUENCE {
630 06 3: OBJECT IDENTIFIER basicConstraints (2 5 29 19)
635 01 1: BOOLEAN TRUE
638 04 5: OCTET STRING
: 30 03 01 01 FF
: }
: }
: }
: }
645 30 9: SEQUENCE {
647 06 7: OBJECT IDENTIFIER dsaWithSha1 (1 2 840 10040 4 3)
: }
656 03 47: BIT STRING 0 unused bits
: 30 2C 02 14 6A F9 3F 72 30 7F 45 DC E5 50 C1 5E
: 94 A0 6D C7 92 4C E5 E1 02 14 6F 61 B8 65 F7 AA
: DF 46 1B F7 39 0D 0D 88 9E FE B6 83 F7 1A
: }
Housley, Ford, Polk, & Solo [Page 109]
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C.2 Certificate
This section contains an annotated hex dump of a 730 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
constraints extension is not present;
(h) the certificate contains an authority key identifier extension;
and
(i) the certificate includes one alternative name - an RFC 822
address.
0 30 734: SEQUENCE {
4 30 669: SEQUENCE {
8 A0 3: [0] {
10 02 1: INTEGER 2
: }
13 02 1: INTEGER 18
16 30 9: SEQUENCE {
18 06 7: OBJECT IDENTIFIER dsaWithSha1 (1 2 840 10040 4 3)
: }
27 30 42: SEQUENCE {
29 31 11: SET {
31 30 9: SEQUENCE {
33 06 3: OBJECT IDENTIFIER countryName (2 5 4 6)
38 13 2: PrintableString 'US'
: }
: }
42 31 12: SET {
44 30 10: SEQUENCE {
46 06 3: OBJECT IDENTIFIER organizationName (2 5 4 10)
51 13 3: PrintableString 'gov'
: }
: }
56 31 13: SET {
58 30 11: SEQUENCE {
60 06 3: OBJECT IDENTIFIER
organizationalUnitName (2 5 4 11)
65 13 4: PrintableString 'NIST'
: }
: }
Housley, Ford, Polk, & Solo [Page 110]
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: }
71 30 30: SEQUENCE {
73 17 13: UTCTime '970730000000Z'
88 17 13: UTCTime '971201000000Z'
: }
103 30 61: SEQUENCE {
105 31 11: SET {
107 30 9: SEQUENCE {
109 06 3: OBJECT IDENTIFIER countryName (2 5 4 6)
114 13 2: PrintableString 'US'
: }
: }
118 31 12: SET {
120 30 10: SEQUENCE {
122 06 3: OBJECT IDENTIFIER organizationName (2 5 4 10)
127 13 3: PrintableString 'gov'
: }
: }
132 31 13: SET {
134 30 11: SEQUENCE {
136 06 3: OBJECT IDENTIFIER
organizationalUnitName (2 5 4 11)
141 13 4: PrintableString 'NIST'
: }
: }
147 31 17: SET {
149 30 15: SEQUENCE {
151 06 3: OBJECT IDENTIFIER commonName (2 5 4 3)
156 13 8: PrintableString 'Tim Polk'
: }
: }
: }
166 30 439: SEQUENCE {
170 30 300: SEQUENCE {
174 06 7: OBJECT IDENTIFIER dsa (1 2 840 10040 4 1)
183 30 287: SEQUENCE {
187 02 129: INTEGER
: 00 B6 8B 0F 94 2B 9A CE A5 25 C6 F2 ED FC FB 95
: 32 AC 01 12 33 B9 E0 1C AD 90 9B BC 48 54 9E F3
: 94 77 3C 2C 71 35 55 E6 FE 4F 22 CB D5 D8 3E 89
: 93 33 4D FC BD 4F 41 64 3E A2 98 70 EC 31 B4 50
: DE EB F1 98 28 0A C9 3E 44 B3 FD 22 97 96 83 D0
: 18 A3 E3 BD 35 5B FF EE A3 21 72 6A 7B 96 DA B9
: 3F 1E 5A 90 AF 24 D6 20 F0 0D 21 A7 D4 02 B9 1A
: FC AC 21 FB 9E 94 9E 4B 42 45 9E 6A B2 48 63 FE
: 43
319 02 21: INTEGER
: 00 B2 0D B0 B1 01 DF 0C 66 24 FC 13 92 BA 55 F7
Housley, Ford, Polk, & Solo [Page 111]
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: 7D 57 74 81 E5
342 02 129: INTEGER
: 00 9A BF 46 B1 F5 3F 44 3D C9 A5 65 FB 91 C0 8E
: 47 F1 0A C3 01 47 C2 44 42 36 A9 92 81 DE 57 C5
: E0 68 86 58 00 7B 1F F9 9B 77 A1 C5 10 A5 80 91
: 78 51 51 3C F6 FC FC CC 46 C6 81 78 92 84 3D F4
: 93 3D 0C 38 7E 1A 5B 99 4E AB 14 64 F6 0C 21 22
: 4E 28 08 9C 92 B9 66 9F 40 E8 95 F6 D5 31 2A EF
: 39 A2 62 C7 B2 6D 9E 58 C4 3A A8 11 81 84 6D AF
: F8 B4 19 B4 C2 11 AE D0 22 3B AA 20 7F EE 1E 57
: 18
: }
: }
474 03 132: BIT STRING 0 unused bits
: 02 81 80 30 B6 75 F7 7C 20 31 AE 38 BB 7E 0D 2B
: AB A0 9C 4B DF 20 D5 24 13 3C CD 98 E5 5F 6C B7
: C1 BA 4A BA A9 95 80 53 F0 0D 72 DC 33 37 F4 01
: 0B F5 04 1F 9D 2E 1F 62 D8 84 3A 9B 25 09 5A 2D
: C8 46 8E 2B D4 F5 0D 3B C7 2D C6 6C B9 98 C1 25
: 3A 44 4E 8E CA 95 61 35 7C CE 15 31 5C 23 13 1E
: A2 05 D1 7A 24 1C CB D3 72 09 90 FF 9B 9D 28 C0
: A1 0A EC 46 9F 0D B8 D0 DC D0 18 A6 2B 5E F9 8F
: B5 95 BE
: }
609 A3 66: [3] {
611 30 64: SEQUENCE {
613 30 25: SEQUENCE {
615 06 3: OBJECT IDENTIFIER subjectAltName (2 5 29 17)
620 04 18: OCTET STRING
: 30 10 81 0E 77 70 6F 6C 6B 40 6E 69 73 74 2E 67
: 6F 76
: }
640 30 35: SEQUENCE {
642 06 3: OBJECT IDENTIFIER
authorityKeyIdentifier (2 5 29 35)
647 04 28: OCTET STRING
: 30 1A 80 18 04 16 04 14 E7 26 C5 54 CD 5B A3 6F
: 35 68 95 AA D5 FF 1C 21 E4 22 75 D6
: }
: }
: }
: }
677 30 9: SEQUENCE {
679 06 7: OBJECT IDENTIFIER dsaWithSha1 (1 2 840 10040 4 3)
: }
688 03 48: BIT STRING 0 unused bits
: 30 2D 02 14 37 FC 44 BF 7F 8D 18 1F 40 04 2F CF
: EA CC 22 B2 16 01 FF 13 02 15 00 97 D0 24 96 0F
Housley, Ford, Polk, & Solo [Page 112]
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: 64 8A C3 8D 41 B2 0E B9 26 D5 31 D1 A0 F1 BC
: }
C.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 256;
(b) the certificate is signed with RSA and the MD2 hash algorithm;
(c) the issuer's distinguished name is OU=Dept. Arquitectura de
Computadors; O=Universitat Politecnica de Catalunya; C=ES
(d) and the subject's distinguished name is CN=Francisco Jordan;
OU=Dept. Arquitectura de Computadors; O=Universitat Politecnica de
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;
(g) the certificate is an end entity certificate (not a CA
certificate);
(h) the certificate includes an alternative subject name and an
alternative issuer name - bothe are URLs;
(i) the certificate include an authority key identifier and
certificate policies extensions; and
(j) the certificate includes a critical key usage extension
specifying the public is intended for generation of digital
signatures.
0 30 654: SEQUENCE {
4 30 503: SEQUENCE {
8 A0 3: [0] {
10 02 1: INTEGER 2
: }
13 02 2: INTEGER 256
17 30 13: SEQUENCE {
19 06 9: OBJECT IDENTIFIER
: sha1withRSAEncryption (1 2 840 113549 1 1 5)
30 05 0: NULL
: }
32 30 42: SEQUENCE {
34 31 11: SET {
36 30 9: SEQUENCE {
38 06 3: OBJECT IDENTIFIER countryName (2 5 4 6)
43 13 2: PrintableString 'US'
: }
: }
47 31 12: SET {
49 30 10: SEQUENCE {
51 06 3: OBJECT IDENTIFIER
Housley, Ford, Polk, & Solo [Page 113]
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organizationalUnitName (2 5 4 11)
56 13 3: PrintableString 'gov'
: }
: }
61 31 13: SET {
63 30 11: SEQUENCE {
65 06 3: OBJECT IDENTIFIER organizationName (2 5 4 10)
70 13 4: PrintableString 'NIST'
: }
: }
: }
76 30 30: SEQUENCE {
78 17 13: UTCTime '960521095826Z'
93 17 13: UTCTime '970521095826Z'
: }
108 30 61: SEQUENCE {
110 31 11: SET {
112 30 9: SEQUENCE {
114 06 3: OBJECT IDENTIFIER countryName (2 5 4 6)
119 13 2: PrintableString 'US'
: }
: }
123 31 12: SET {
125 30 10: SEQUENCE {
127 06 3: OBJECT IDENTIFIER
organizationalUnitName (2 5 4 11)
132 13 3: PrintableString 'gov'
: }
: }
137 31 13: SET {
139 30 11: SEQUENCE {
141 06 3: OBJECT IDENTIFIER organizationName (2 5 4 10)
146 13 4: PrintableString 'NIST'
: }
: }
152 31 17: SET {
154 30 15: SEQUENCE {
156 06 3: OBJECT IDENTIFIER commonName (2 5 4 3)
161 13 8: PrintableString 'Tim Polk'
: }
: }
: }
171 30 159: SEQUENCE {
174 30 13: SEQUENCE {
176 06 9: OBJECT IDENTIFIER
rsaEncryption (1 2 840 113549 1 1 1)
187 05 0: NULL
: }
Housley, Ford, Polk, & Solo [Page 114]
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189 03 141: BIT STRING 0 unused bits
: 30 81 89 02 81 81 00 E1 CE 06 C9 D7 00 DF 65 27
: 45 1E 63 6A 09 A0 A0 10 4B AF DF 9D 36 1D 44 1F
: B7 07 5D 36 92 09 6A 1A 96 C7 4E D9 86 0D 0F 77
: 94 F5 82 62 68 9A F2 D7 76 F5 9A 35 C7 B3 7F 4F
: BE 64 CF A3 0C B3 84 32 80 F5 CA 77 29 C9 76 0B
: 4C 38 19 EE 61 6F BA 68 E0 03 85 46 34 AB 84 64
: 7F 43 69 02 C0 20 86 BD B1 D4 AD 21 A9 1A 8F CF
: 96 83 86 92 57 5B 43 09 28 4C F2 5A 04 AD E5 DE
: 9E 4F E8 38 3C F0 89 02 03 01 00 01
: }
333 A3 175: [3] {
336 30 172: SEQUENCE {
339 30 63: SEQUENCE {
341 06 3: OBJECT IDENTIFIER subjectAltName (2 5 29 17)
346 04 56: OCTET STRING
: 30 36 86 34 68 74 74 70 3A 2F 2F 77 77 77 2E 69
: 74 6C 2E 6E 69 73 74 2E 67 6F 76 2F 64 69 76 38
: 39 33 2F 73 74 61 66 66 2F 70 6F 6C 6B 2F 69 6E
: 64 65 78 2E 68 74 6D 6C
: }
404 30 31: SEQUENCE {
406 06 3: OBJECT IDENTIFIER issuerAltName (2 5 29 18)
411 04 24: OCTET STRING
: 30 16 86 14 68 74 74 70 3A 2F 2F 77 77 77 2E 6E
: 69 73 74 2E 67 6F 76 2F
: }
437 30 31: SEQUENCE {
439 06 3: OBJECT IDENTIFIER
authorityKeyIdentifier (2 5 29 35)
444 04 24: OCTET STRING
: 30 16 80 14 30 12 80 10 0E 6B 3A BF 04 EA 04 C3
: 0E 6B 3A BF 04 EA 04 C3
: }
470 30 23: SEQUENCE {
472 06 3: OBJECT IDENTIFIER
certificatePolicies (2 5 29 32)
477 04 16: OCTET STRING
: 30 0E 30 0C 06 0A 60 86 48 01 65 03 02 01 30 09
: }
495 30 14: SEQUENCE {
497 06 3: OBJECT IDENTIFIER keyUsage (2 5 29 15)
502 01 1: BOOLEAN TRUE
505 04 4: OCTET STRING
: 03 02 07 80
: }
: }
: }
Housley, Ford, Polk, & Solo [Page 115]
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: }
511 30 13: SEQUENCE {
513 06 9: OBJECT IDENTIFIER
: sha1withRSAEncryption (1 2 840 113549 1 1 5)
524 05 0: NULL
: }
526 03 129: BIT STRING 0 unused bits
: C1 25 6F AB 72 C0 5D DA E4 2F D5 E1 B0 25 D8 B4
: F1 82 95 D6 0D A5 4E 4F A1 23 E1 13 A4 9C 3D C5
: 7F FD 05 EC 75 06 30 66 97 75 A6 5D 8F 97 BA B4
: EC A9 43 19 8D B7 54 FD E9 AD 43 B8 3C 8B D3 9E
: C7 C7 27 E3 1A AD D3 79 AC 65 5A 52 78 C4 D0 43
: 81 50 F7 8A BA E2 30 1A 6D D0 78 A0 4E AE 2E 79
: 37 0C 93 05 5C D1 9C 1B B2 62 73 D1 EA 50 B7 84
: 29 92 74 34 CF BA AA 2C 4D 43 59 EF 98 0C 41 6C
: }
C.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.
0 30 203: SEQUENCE {
3 30 140: SEQUENCE {
6 02 1: INTEGER 1
9 30 9: SEQUENCE {
11 06 7: OBJECT IDENTIFIER dsaWithSha1 (1 2 840 10040 4 3)
: }
20 30 42: SEQUENCE {
22 31 11: SET {
24 30 9: SEQUENCE {
26 06 3: OBJECT IDENTIFIER countryName (2 5 4 6)
31 13 2: PrintableString 'US'
: }
: }
35 31 12: SET {
37 30 10: SEQUENCE {
39 06 3: OBJECT IDENTIFIER organizationName (2 5 4 10)
44 13 3: PrintableString 'gov'
: }
: }
49 31 13: SET {
51 30 11: SEQUENCE {
53 06 3: OBJECT IDENTIFIER
organizationalUnitName (2 5 4 11)
Housley, Ford, Polk, & Solo [Page 116]
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58 13 4: PrintableString 'NIST'
: }
: }
: }
64 17 13: UTCTime '970807000000Z'
79 17 13: UTCTime '970907000000Z'
94 30 34: SEQUENCE {
96 30 32: SEQUENCE {
98 02 1: INTEGER 18
101 17 13: UTCTime '970731000000Z'
116 30 12: SEQUENCE {
118 30 10: SEQUENCE {
120 06 3: OBJECT IDENTIFIER cRLReason (2 5 29 21)
125 04 3: OCTET STRING
: 0A 01 01
: }
: }
: }
: }
130 A0 14: [0] {
132 30 12: SEQUENCE {
134 30 10: SEQUENCE {
136 06 3: OBJECT IDENTIFIER cRLNumber (2 5 29 20)
141 04 3: OCTET STRING
: 02 01 12
: }
: }
: }
: }
146 30 9: SEQUENCE {
148 06 7: OBJECT IDENTIFIER dsaWithSha1 (1 2 840 10040 4 3)
: }
157 03 47: BIT STRING 0 unused bits
: 30 2C 02 14 79 1F F6 93 0B 84 06 D6 A0 7C 8D 68
: A7 52 2E 5F 3F 89 9B 4B 02 14 66 D4 B5 2A 68 36
: 9B 72 88 58 E3 89 19 AD 81 89 2E 96 BB CC
: }
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Appendix D. 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 E. 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
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process shall be
Housley, Ford, Polk, & Solo [Page 118]
INTERNET DRAFT March 2001
followed, or as 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 119]
