Internet Draft C. Adams
PKIX Working Group Entrust, Inc.
April, 2003 S. Farrell
Expires in 6 Months Baltimore Technologies
Internet X.509 Public Key Infrastructure
Certificate Management Protocol
<draft-ietf-pkix-rfc2510bis-08.txt>
Status of this Memo
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Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document describes the Internet X.509 Public Key Infrastructure
(PKI) Certificate Management Protocol (CMP). Protocol messages are
defined for X.509v3 certificate creation and management. CMP provides
online interactions between PKI components, including an exchange
between a Certification Authority (CA) and a client system.
Adams & Farrell Expires Oct. 2003 [Page 1]
Introduction and Terminology
This document describes the Internet X.509 Public Key Infrastructure
(PKI) Certificate Management Protocol (CMP). Protocol messages are
defined for certificate creation and management. The term "certificate"
in this document refers to an X.509v3 Certificate as defined in
[COR95, X509-AM].
The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and "OPTIONAL" in this document (in uppercase,
as shown) are to be interpreted as described in [RFC2119].
Table of Contents
1. PKI Management Overview ............................................ 4
1.1 PKI Management Model ........................................... 4
1.2 Definitions of PKI Entities .................................... 4
1.3 PKI Management Requirements .................................... 6
1.4 PKI Management Operations ...................................... 8
2. Assumptions and Restrictions ....................................... 12
2.1 End Entity Initialization ...................................... 12
2.2 Initial Registration/Certification ............................. 12
2.3 Proof of Possession (POP) of Private Key ....................... 15
2.4 Root CA Key Update ............................................. 17
3. Data Structures .................................................... 21
3.1 Overall PKI Message ............................................ 21
3.2 Common Data Structures ......................................... 28
3.3 Operation-Specific Data Structures ............................. 38
3.3.1 Initialization Request ................................... 38
3.3.2 Initialization Response .................................. 38
3.3.3 Certification Request .................................... 38
3.3.4 Certification Response ................................... 39
3.3.5 Key Update Request ....................................... 40
3.3.6 Key Update Response ...................................... 40
3.3.7 Key Recovery Request ..................................... 40
3.3.8 Key Recovery Response .................................... 40
3.3.9 Revocation Request ....................................... 41
3.3.10 Revocation Response ...................................... 41
3.3.11 Cross-Certification Request .............................. 41
3.3.12 Cross-Certification Response ............................. 42
3.3.13 CA Key Update Announcement ............................... 42
3.3.14 Certificate Announcement ................................. 42
3.3.15 Revocation Announcement .................................. 42
3.3.16 CRL Announcement ......................................... 43
3.3.17 PKI Confirmation ......................................... 43
3.3.18 Certificate Confirmation ................................. 43
3.3.19 PKI General Message ...................................... 44
3.3.20 PKI General Response ..................................... 47
3.3.21 Error Message ............................................ 47
3.3.22 Polling Request and Response ............................. 47
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4. Mandatory PKI Management Functions ................................. 49
4.1 Root CA Initialization ......................................... 49
4.2 Root CA Key Update ............................................. 50
4.3 Subordinate CA Initialization .................................. 50
4.4 CRL Production ................................................. 50
4.5 PKI Information Request ........................................ 50
4.6 Cross-Certification ............................................ 51
4.7 End Entity Initialization ...................................... 53
4.8 Certificate Request ............................................ 54
4.9 Key Update ..................................................... 54
5. Version Negotiation ................................................ 55
5.1 Supporting RFC 2510 Implementations ............................ 55
Security Considerations ............................................... 56
References ............................................................ 57
Acknowledgements ...................................................... 58
Authors' Addresses .................................................... 58
Appendix A: Reasons for the presence of RAs ........................... 59
Appendix B: PKI Management Message Profiles (REQUIRED) ................ 60
Appendix C: PKI Management Message Profiles (OPTIONAL) ................ 70
Appendix D: Request Message Behavioral Clarifications ................. 77
Appendix E: The Use of "Revocation Passphrase" ........................ 78
Appendix F: "Compilable" ASN.1 Module Using 1988 Syntax ............... 80
Appendix G: Registration of MIME Type for E-Mail or HTTP Use .......... 91
Full Copyright Statement .............................................. 92
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1 PKI Management Overview
The PKI must be structured to be consistent with the types of
individuals who must administer it. Providing such administrators
with unbounded choices not only complicates the software required but
also increases the chances that a subtle mistake by an administrator
or software developer will result in broader compromise. Similarly,
restricting administrators with cumbersome mechanisms will cause them
not to use the PKI.
Management protocols are REQUIRED to support on-line interactions
between Public Key Infrastructure (PKI) components. For example, a
management protocol might be used between a Certification Authority
(CA) and a client system with which a key pair is associated, or
between two CAs that issue cross-certificates for each other.
1.1 PKI Management Model
Before specifying particular message formats and procedures we first
define the entities involved in PKI management and their interactions
(in terms of the PKI management functions required). We then group
these functions in order to accommodate different identifiable types
of end entities.
1.2 Definitions of PKI Entities
The entities involved in PKI management include the end entity (i.e.,
the entity to whom the certificate is issued) and the
certification authority (i.e., the entity that issues the certificate).
A registration authority MAY also be involved in PKI management.
1.2.1 Subjects and End Entities
The term "subject" is used here to refer to the entity to whom the
certificate is issued, typically named in the subject or
subjectAltName field of a certificate. When we wish to distinguish the
tools and/or software used by the subject (e.g., a local certificate
management module) we will use the term "subject equipment". In
general, the term "end entity" (EE) rather than subject is preferred
in order to avoid confusion with the field name.
It is important to note that the end entities here will include not
only human users of applications, but also applications themselves
(e.g., for IP security). This factor influences the protocols which
the PKI management operations use; for example, application software
is far more likely to know exactly which certificate extensions are
required than are human users. PKI management entities are also end
entities in the sense that they are sometimes named in the subject or
subjectAltName field of a certificate or cross-certificate. Where
Adams & Farrell Expires Oct. 2003 [Page 4]
appropriate, the term "end-entity" will be used to refer to end
entities who are not PKI management entities.
All end entities require secure local access to some information --
at a minimum, their own name and private key, the name of a CA which
is directly trusted by this entity and that CA's public key (or a
fingerprint of the public key where a self-certified version is
available elsewhere). Implementations MAY use secure local storage
for more than this minimum (e.g., the end entity's own certificate or
application-specific information). The form of storage will also vary
-- from files to tamper-resistant cryptographic tokens. Such local
trusted storage is referred to here as the end entity's Personal
Security Environment (PSE).
Though PSE formats are beyond the scope of this document (they are
very dependent on equipment, et cetera), a generic interchange format
for PSEs is defined here - a certification response message MAY be
used.
1.2.2 Certification Authority
The certification authority (CA) may or may not actually be a real
"third party" from the end entity's point of view. Quite often, the
CA will actually belong to the same organization as the end entities
it supports.
Again, we use the term CA to refer to the entity named in the issuer
field of a certificate; when it is necessary to distinguish the
software or hardware tools used by the CA we use the term "CA
equipment".
The CA equipment will often include both an "off-line" component and
an "on-line" component, with the CA private key only available to the
"off-line" component. This is, however, a matter for implementers
(though it is also relevant as a policy issue).
We use the term "root CA" to indicate a CA that is directly trusted
by an end entity; that is, securely acquiring the value of a root CA
public key requires some out-of-band step(s). This term is not meant
to imply that a root CA is necessarily at the top of any hierarchy,
simply that the CA in question is trusted directly.
A "subordinate CA" is one that is not a root CA for the end entity in
question. Often, a subordinate CA will not be a root CA for any
entity but this is not mandatory.
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1.2.3 Registration Authority
In addition to end-entities and CAs, many environments call for the
existence of a Registration Authority (RA) separate from the
Certification Authority. The functions which the registration
authority may carry out will vary from case to case but MAY include
personal authentication, token distribution, revocation reporting,
name assignment, key generation, archival of key pairs, et cetera.
This document views the RA as an OPTIONAL component - when it is not
present the CA is assumed to be able to carry out the RA's functions
so that the PKI management protocols are the same from the end-
entity's point of view.
Again, we distinguish, where necessary, between the RA and the tools
used (the "RA equipment").
Note that an RA is itself an end entity. We further assume that all
RAs are in fact certified end entities and that RAs have private keys
that are usable for signing. How a particular CA equipment identifies
some end entities as RAs is an implementation issue (i.e., this
document specifies no special RA certification operation). We do not
mandate that the RA is certified by the CA with which it is
interacting at the moment (so one RA may work with more than one CA
whilst only being certified once).
In some circumstances end entities will communicate directly with a
CA even where an RA is present. For example, for initial registration
and/or certification the subject may use its RA, but communicate
directly with the CA in order to refresh its certificate.
1.3 PKI Management Requirements
The protocols given here meet the following requirements on PKI
management.
1. PKI management must conform to the ISO 9594-8 standard and the
associated amendments (certificate extensions)
2. PKI management must conform to the other parts of this series.
3. It must be possible to regularly update any key pair without
affecting any other key pair.
4. The use of confidentiality in PKI management protocols must be
kept to a minimum in order to ease regulatory problems.
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5. PKI management protocols must allow the use of different
industry-standard cryptographic algorithms, (specifically
including RSA, DSA, MD5, SHA-1) -- this means that any given
CA, RA, or end entity may, in principle, use whichever
algorithms suit it for its own key pair(s).
6. PKI management protocols must not preclude the generation of
key pairs by the end-entity concerned, by an RA, or by a CA --
key generation may also occur elsewhere, but for the purposes
of PKI management we can regard key generation as occurring
wherever the key is first present at an end entity, RA, or CA.
7. PKI management protocols must support the publication of
certificates by the end-entity concerned, by an RA, or by a CA.
Different implementations and different environments may choose
any of the above approaches.
8. PKI management protocols must support the production of
Certificate Revocation Lists (CRLs) by allowing certified end
entities to make requests for the revocation of certificates -
this must be done in such a way that the denial-of-service
attacks which are possible are not made simpler.
9. PKI management protocols must be usable over a variety of
"transport" mechanisms, specifically including mail, http,
TCP/IP and ftp.
10. Final authority for certification creation rests with the CA;
no RA or end-entity equipment can assume that any certificate
issued by a CA will contain what was requested -- a CA may
alter certificate field values or may add, delete or alter
extensions according to its operating policy. In other words,
all PKI entities (end-entities, RAs, and CAs) must be capable
of handling responses to requests for certificates in which
the actual certificate issued is different from that requested
(for example, a CA may shorten the validity period requested).
Note that policy may dictate that the CA must not publish or
otherwise distribute the certificate until the requesting
entity has reviewed and accepted the newly-created certificate
(typically through use of the certConf message).
11. A graceful, scheduled change-over from one non-compromised CA
key pair to the next (CA key update) must be supported (note
that if the CA key is compromised, re-initialization must be
performed for all entities in the domain of that CA). An end
entity whose PSE contains the new CA public key (following a
CA key update) must also be able to verify certificates
verifiable using the old public key. End entities who directly
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trust the old CA key pair must also be able to verify
certificates signed using the new CA private key. (Required
for situations where the old CA public key is "hardwired" into
the end entity's cryptographic equipment).
12. The Functions of an RA may, in some implementations or
environments, be carried out by the CA itself. The protocols
must be designed so that end entities will use the same
protocol (but, of course, not the same key!) regardless of
whether the communication is with an RA or CA.
13. Where an end entity requests a certificate containing a given
public key value, the end entity must be ready to demonstrate
possession of the corresponding private key value. This may be
accomplished in various ways, depending on the type of
certification request. See Section 2.3, "Proof of Possession
of Private Key", for details of the in-band methods defined
for the PKIX-CMP (i.e., Certificate Management Protocol)
messages.
1.4 PKI Management Operations
The following diagram shows the relationship between the entities
defined above in terms of the PKI management operations. The letters
in the diagram indicate "protocols" in the sense that a defined set
of PKI management messages can be sent along each of the lettered
lines.
Adams & Farrell Expires Oct. 2003 [Page 8]
+---+ cert. publish +------------+ j
| | <--------------------- | End Entity | <-------
| C | g +------------+ "out-of-band"
| e | | ^ loading
| r | | | initial
| t | a | | b registration/
| | | | certification
| / | | | key pair recovery
| | | | key pair update
| C | | | certificate update
| R | PKI "USERS" V | revocation request
| L | -------------------+-+-----+-+------+-+-------------------
| | PKI MANAGEMENT | ^ | ^
| | ENTITIES a | | b a | | b
| R | V | | |
| e | g +------+ d | |
| p | <------------ | RA | <-----+ | |
| o | cert. | | ----+ | | |
| s | publish +------+ c | | | |
| i | | | | |
| t | V | V |
| o | g +------------+ i
| r | <------------------------| CA |------->
| y | h +------------+ "out-of-band"
| | cert. publish | ^ publication
| | CRL publish | |
+---+ | | cross-certification
e | | f cross-certificate
| | update
| |
V |
+------+
| CA-2 |
+------+
Figure 1 - PKI Entities
At a high level the set of operations for which management messages
are defined can be grouped as follows.
1 CA establishment: When establishing a new CA, certain steps are
required (e.g., production of initial CRLs, export of CA public
key).
2 End entity initialization: this includes importing a root CA
public key and requesting information about the options
supported by a PKI management entity.
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3 Certification: various operations result in the creation of new
certificates:
3.1 initial registration/certification: This is the process
whereby an end entity first makes itself known to a CA or
RA, prior to the CA issuing a certificate or certificates
for that end entity. The end result of this process (when it
is successful) is that a CA issues a certificate for an end
entity's public key, and returns that certificate to the end
entity and/or posts that certificate in a public repository.
This process may, and typically will, involve multiple
"steps", possibly including an initialization of the end
entity's equipment. For example, the end entity's equipment
must be securely initialized with the public key of a CA, to
be used in validating certificate paths. Furthermore, an
end entity typically needs to be initialized with its own
key pair(s).
3.2 key pair update: Every key pair needs to be updated
regularly (i.e., replaced with a new key pair), and a new
certificate needs to be issued.
3.3 certificate update: As certificates expire they may be
"refreshed" if nothing relevant in the environment has
changed.
3.4 CA key pair update: As with end entities, CA key pairs need
to be updated regularly; however, different mechanisms are
required.
3.5 cross-certification request: One CA requests issuance of a
cross-certificate from another CA. For the purposes of this
standard, the following terms are defined. A "cross-
certificate" is a certificate in which the subject CA and
the issuer CA are distinct and SubjectPublicKeyInfo contains
a verification key (i.e., the certificate has been issued
for the subject CA's signing key pair). When it is
necessary to distinguish more finely, the following terms
may be used: a cross-certificate is called an "inter-domain
cross-certificate" if the subject and issuer CAs belong to
different administrative domains; it is called an "intra-
domain cross-certificate" otherwise.
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Notes:
Note 1. The above definition of "cross-certificate" aligns
with the defined term "CA-certificate" in X.509. Note that
this term is not to be confused with the X.500 "cACertificate"
attribute type, which is unrelated.
Note 2. In many environments the term "cross-certificate",
unless further qualified, will be understood to be synonymous
with "inter-domain cross-certificate" as defined above.
Note 3. Issuance of cross-certificates may be, but is not
necessarily, mutual; that is, two CAs may issue
cross-certificates for each other.
3.6 cross-certificate update: Similar to a normal certificate
update but involving a cross-certificate.
4 Certificate/CRL discovery operations: some PKI management
operations result in the publication of certificates or CRLs:
4.1 certificate publication: Having gone to the trouble of
producing a certificate, some means for publishing it is
needed. The "means" defined in PKIX MAY involve the
messages specified in Sections 3.3.13 - 3.3.16, or MAY
involve other methods (LDAP, for example) as described in
[RFC2559, RFC2585] (the "Operational Protocols" documents
of the PKIX series of specifications).
4.2 CRL publication: As for certificate publication.
5 Recovery operations: some PKI management operations are used
when an end entity has "lost" its PSE:
5.1 key pair recovery: As an option, user client key materials
(e.g., a user's private key used for decryption purposes)
MAY be backed up by a CA, an RA, or a key backup system
associated with a CA or RA. If an entity needs to recover
these backed up key materials (e.g., as a result of a
forgotten password or a lost key chain file), a protocol
exchange may be needed to support such recovery.
6 Revocation operations: some PKI operations result in the
creation of new CRL entries and/or new CRLs:
6.1 revocation request: An authorized person advises a CA of an
abnormal situation requiring certificate revocation.
Adams & Farrell Expires Oct. 2003 [Page 11]
7 PSE operations: whilst the definition of PSE operations (e.g.,
moving a PSE, changing a PIN, etc.) are beyond the scope of this
specification, we do define a PKIMessage (CertRepMessage) which
can form the basis of such operations.
Note that on-line protocols are not the only way of implementing the
above operations. For all operations 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 operations MAY be achieved as part of the physical
token delivery.
Later sections define a set of standard messages supporting the above
operations. Transport protocols for conveying these exchanges in
different environments (file based, on-line, E-mail, and WWW) are
beyond the scope of this document and are specified separately.
2. Assumptions and restrictions
2.1 End entity initialization
The first step for an end entity in dealing with PKI management
entities is to request information about the PKI functions supported
and to securely acquire a copy of the relevant root CA public key(s).
2.2 Initial registration/certification
There are many schemes that can be used to achieve initial
registration and certification of end entities. No one method is
suitable for all situations due to the range of policies which a CA
may implement and the variation in the types of end entity which can
occur.
We can however, classify the initial registration / certification
schemes that are supported by this specification. Note that the word
"initial", above, is crucial - we are dealing with the situation
where the end entity in question has had no previous contact with the
PKI. Where the end entity already possesses certified keys then some
simplifications/alternatives are possible.
Having classified the schemes that are supported by this
specification we can then specify some as mandatory and some as
optional. The goal is that the mandatory schemes cover a sufficient
number of the cases which will arise in real use, whilst the optional
schemes are available for special cases which arise less frequently.
In this way we achieve a balance between flexibility and ease of
implementation.
Adams & Farrell Expires Oct. 2003 [Page 12]
We will now describe the classification of initial registration /
certification schemes.
2.2.1 Criteria used
2.2.1.1 Initiation of registration / certification
In terms of the PKI messages which are produced we can regard the
initiation of the initial registration / certification exchanges as
occurring wherever the first PKI message relating to the end entity
is produced. Note that the real-world initiation of the registration
/ certification procedure may occur elsewhere (e.g., a personnel
department may telephone an RA operator).
The possible locations are at the end entity, an RA, or a CA.
2.2.1.2 End entity message origin authentication
The on-line messages produced by the end entity that requires a
certificate may be authenticated or not. The requirement here is to
authenticate the origin of any messages from the end entity to the
PKI (CA/RA).
In this specification, such authentication is achieved by the PKI
(CA/RA) issuing the end entity with a secret value (initial
authentication key) and reference value (used to identify the
secret value) via some out-of-band means. The initial authentication
key can then be used to protect relevant PKI messages.
We can thus classify the initial registration/certification scheme
according to whether or not the on-line end entity -> PKI messages
are authenticated or not.
Note 1: We do not discuss the authentication of the PKI -> end entity
messages here as this is always REQUIRED. In any case, it can be
achieved simply once the root-CA public key has been installed at the
end entity's equipment or it can be based on the initial
authentication key.
Note 2: An initial registration / certification procedure can be
secure where the messages from the end entity are authenticated via
some out- of-band means (e.g., a subsequent visit).
2.2.1.3 Location of key generation
In this specification, "key generation" is regarded as occurring
wherever either the public or private component of a key pair first
occurs in a PKIMessage. Note that this does not preclude a
Adams & Farrell Expires Oct. 2003 [Page 13]
centralized key generation service - the actual key pair MAY have
been generated elsewhere and transported to the end entity, RA, or CA
using a (proprietary or standardized) key generation request/response
protocol (outside the scope of this specification).
There are thus three possibilities for the location of "key
generation": the end entity, an RA, or a CA.
2.2.1.4 Confirmation of successful certification
Following the creation of an initial certificate for an end entity,
additional assurance can be gained by having the end entity
explicitly confirm successful receipt of the message containing (or
indicating the creation of) the certificate. Naturally, this
confirmation message must be protected (based on the initial
authentication key or other means).
This gives two further possibilities: confirmed or not.
2.2.2 Mandatory schemes
The criteria above allow for a large number of initial registration /
certification schemes. This specification mandates that conforming CA
equipment, RA equipment, and EE equipment MUST support the second
scheme listed below (Section 2.2.2.2). Any entity MAY additionally
support other schemes, if desired.
2.2.2.1 Centralized scheme
In terms of the classification above, this scheme is, in some ways,
the simplest possible, where:
- initiation occurs at the certifying CA;
- no on-line message authentication is required;
- "key generation" occurs at the certifying CA (see Section 2.2.1.3);
- no confirmation message is required.
In terms of message flow, this scheme means that the only message
required is sent from the CA to the end entity. The message must
contain the entire PSE for the end entity. Some out-of-band means
must be provided to allow the end entity to authenticate the message
received and decrypt any encrypted values.
Adams & Farrell Expires Oct. 2003 [Page 14]
2.2.2.2 Basic authenticated scheme
In terms of the classification above, this scheme is where:
- initiation occurs at the end entity;
- message authentication is REQUIRED;
- "key generation" occurs at the end entity (see Section 2.2.1.3);
- a confirmation message is REQUIRED.
In terms of message flow, the basic authenticated scheme is as
follows:
End entity RA/CA
========== =============
out-of-band distribution of Initial Authentication
Key (IAK) and reference value (RA/CA -> EE)
Key generation
Creation of certification request
Protect request with IAK
-->>--certification request-->>--
verify request
process request
create response
--<<--certification response--<<--
handle response
create confirmation
-->>--cert conf message-->>--
verify confirmation
create response
--<<-- conf ack (optional) --<<--
handle response
(Where verification of the cert confirmation message fails, the RA/CA
MUST revoke the newly issued certificate if it has been published or
otherwise made available.)
2.3 Proof of Possession (POP) of Private Key
In order to prevent certain attacks and to allow a CA/RA to properly
check the validity of the binding between an end entity and a key
pair, the PKI management operations specified here make it possible
for an end entity to prove that it has possession of (i.e., is able
to use) the private key corresponding to the public key for which a
certificate is requested. A given CA/RA is free to choose how to
enforce POP (e.g., out-of-band procedural means versus PKIX-CMP in-
band messages) in its certification exchanges (i.e., this may be a
policy issue). However, it is REQUIRED that CAs/RAs MUST enforce POP
by some means because there are currently many non-PKIX operational
protocols in use (various electronic mail protocols are one example)
that do not explicitly check the binding between the end entity and
the private key. Until operational protocols that do verify the
Adams & Farrell Expires Oct. 2003 [Page 15]
binding (for signature, encryption, and key agreement key pairs)
exist, and are ubiquitous, this binding can only be assumed to have
been verified by the CA/RA. Therefore, if the binding is not verified
by the CA/RA, certificates in the Internet Public-Key Infrastructure
end up being somewhat less meaningful.
POP is accomplished in different ways depending upon the type of key
for which a certificate is requested. If a key can be used for
multiple purposes (e.g., an RSA key) then any appropriate method MAY
be used (e.g., a key which may be used for signing, as well as other
purposes, SHOULD NOT be sent to the CA/RA in order to prove
possession).
This specification explicitly allows for cases where an end entity
supplies the relevant proof to an RA and the RA subsequently attests
to the CA that the required proof has been received (and validated!).
For example, an end entity wishing to have a signing key certified
could send the appropriate signature to the RA which then simply
notifies the relevant CA that the end entity has supplied the
required proof. Of course, such a situation may be disallowed by some
policies (e.g., CAs may be the only entities permitted to verify POP
during certification).
2.3.1 Signature Keys
For signature keys, the end entity can sign a value to prove
possession of the private key.
2.3.2 Encryption Keys
For encryption keys, the end entity can provide the private key to
the CA/RA, or can be required to decrypt a value in order to prove
possession of the private key (see Section 3.2.8). Decrypting a value
can be achieved either directly or indirectly.
The direct method is for the RA/CA to issue a random challenge to
which an immediate response by the EE is required.
The indirect method is to issue a certificate which is encrypted for
the end entity (and have the end entity demonstrate its ability to
decrypt this certificate in the confirmation message). This allows a
CA to issue a certificate in a form which can only be used by the
intended end entity.
This specification encourages use of the indirect method because this
requires no extra messages to be sent (i.e., the proof can be
demonstrated using the {request, response, confirmation} triple of
messages).
Adams & Farrell Expires Oct. 2003 [Page 16]
2.3.3 Key Agreement Keys
For key agreement keys, the end entity and the PKI management entity
(i.e., CA or RA) must establish a shared secret key in order to prove
that the end entity has possession of the private key.
Note that this need not impose any restrictions on the keys that can
be certified by a given CA -- in particular, for Diffie-Hellman keys
the end entity may freely choose its algorithm parameters -- provided
that the CA can generate a short-term (or one-time) key pair with the
appropriate parameters when necessary.
2.4 Root CA key update
This discussion only applies to CAs that are a root CA for some end
entity.
The basis of the procedure described here is that the CA protects its
new public key using its previous private key and vice versa. Thus
when a CA updates its key pair it must generate two extra
cACertificate attribute values if certificates are made available
using an X.500 directory (for a total of four: OldWithOld;
OldWithNew; NewWithOld; and NewWithNew).
When a CA changes its key pair those entities who have acquired the
old CA public key via "out-of-band" means are most affected. It is
these end entities who will need access to the new CA public key
protected with the old CA private key. However, they will only
require this for a limited period (until they have acquired the new
CA public key via the "out-of-band" mechanism). This will typically
be easily achieved when these end entities' certificates expire.
The data structure used to protect the new and old CA public keys is
a standard certificate (which may also contain extensions). There are
no new data structures required.
Note 1. This scheme does not make use of any of the X.509 v3
extensions as it must be able to work even for version 1
certificates. The presence of the KeyIdentifier extension would make
for efficiency improvements.
Note 2. While the scheme could be generalized to cover cases where
the CA updates its key pair more than once during the validity period
of one of its end entities' certificates, this generalization seems
of dubious value. Not having this generalization simply means that
the validity period of a CA key pair must be greater than the
validity period of any certificate issued by that CA using that key
pair.
Adams & Farrell Expires Oct. 2003 [Page 17]
Note 3. This scheme ensures that end entities will acquire the new CA
public key, at the latest by the expiry of the last certificate they
owned that was signed with the old CA private key (via the
"out-of-band" means). Certificate and/or key update operations
occurring at other times do not necessarily require this (depending on
the end entity's equipment).
2.4.1 CA Operator actions
To change the key of the CA, the CA operator does the following:
1. Generate a new key pair;
2. Create a certificate containing the old CA public key signed
with the new private key (the "old with new" certificate);
3. Create a certificate containing the new CA public key signed
with the old private key (the "new with old" certificate);
4. Create a certificate containing the new CA public key signed
with the new private key (the "new with new" certificate);
5. Publish these new certificates via the repository and/or other
means (perhaps using a CAKeyUpdAnn message);
6. Export the new CA public key so that end entities may acquire
it using the "out-of-band" mechanism (if required).
The old CA private key is then no longer required. The old CA public
key will however remain in use for some time. The time when the old
CA public key is no longer required (other than for non-repudiation)
will be when all end entities of this CA have securely acquired the
new CA public key.
The "old with new" certificate must have a validity period starting
at the generation time of the old key pair and ending at the expiry
date of the old public key.
The "new with old" certificate must have a validity period starting
at the generation time of the new key pair and ending at the time by
which all end entities of this CA will securely possess the new CA
public key (at the latest, the expiry date of the old public key).
The "new with new" certificate must have a validity period starting
at the generation time of the new key pair and ending at or before the
time by which the CA will next update its key pair.
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2.4.2 Verifying Certificates.
Normally when verifying a signature, the verifier verifies (among
other things) the certificate containing the public key of the
signer. However, once a CA is allowed to update its key there are a
range of new possibilities. These are shown in the table below.
Repository contains NEW Repository contains only OLD
and OLD public keys public key (due to, e.g.,
delay in publication)
PSE PSE Contains PSE Contains PSE Contains
Contains OLD public NEW public OLD public
NEW public key key key
key
Signer's Case 1: Case 3: Case 5: Case 7:
certifi- This is In this case Although the In this case
cate is the the verifier CA operator the CA
protected standard must access has not operator has
using NEW case where the updated the not updated
public the repository in repository the the repository
key verifier order to get verifier can and so the
can the value of verify the verification
directly the NEW certificate will FAIL
verify the public key directly -
certificate this is thus
without the same as
using the case 1.
repository
Signer's Case 2: Case 4: Case 6: Case 8:
certifi- In this In this case The verifier Although the
cate is case the the verifier thinks this CA operator
protected verifier can directly is the has not
using OLD must verify the situation of updated the
public access the certificate case 2 and repository the
key repository without will access verifier can
in order using the the verify the
to get the repository repository; certificate
value of however, the directly -
the OLD verification this is thus
public key will FAIL the same as
case 4.
Adams & Farrell Expires Oct. 2003 [Page 19]
2.4.2.1 Verification in cases 1, 4, 5 and 8.
In these cases the verifier has a local copy of the CA public key
which can be used to verify the certificate directly. This is the
same as the situation where no key change has occurred.
Note that case 8 may arise between the time when the CA operator has
generated the new key pair and the time when the CA operator stores
the updated attributes in the repository. Case 5 can only arise if the
CA operator has issued both the signer's and verifier's certificates
during this "gap" (the CA operator SHOULD avoid this as it leads to
the failure cases described below).
2.4.2.2 Verification in case 2.
In case 2 the verifier must get access to the old public key of the
CA. The verifier does the following:
1. Look up the caCertificate attribute in the repository and pick
the OldWithNew certificate (determined based on validity
periods; note that the subject and issuer fields must match);
2. Verify that this is correct using the new CA key (which the
verifier has locally);
3. If correct, check the signer's certificate using the old CA
key.
Case 2 will arise when the CA operator has issued the signer's
certificate, then changed key and then issued the verifier's
certificate, so it is quite a typical case.
2.4.2.3 Verification in case 3.
In case 3 the verifier must get access to the new public key of the
CA. The verifier does the following:
1. Look up the CACertificate attribute in the repository and pick
the NewWithOld certificate (determined based on validity
periods; note that the subject and issuer fields must match);
2. Verify that this is correct using the old CA key (which the
verifier has stored locally);
3. If correct, check the signer's certificate using the new CA
key.
Case 3 will arise when the CA operator has issued the verifier's
certificate, then changed key and then issued the signer's
certificate, so it is also quite a typical case.
Adams & Farrell Expires Oct. 2003 [Page 20]
2.4.2.4 Failure of verification in case 6.
In this case the CA has issued the verifier's PSE containing the new
key without updating the repository attributes. This means that the
verifier has no means to get a trustworthy version of the CA's old
key and so verification fails.
Note that the failure is the CA operator's fault.
2.4.2.5 Failure of verification in case 7.
In this case the CA has issued the signer's certificate protected
with the new key without updating the repository attributes. This
means that the verifier has no means to get a trustworthy version of
the CA's new key and so verification fails.
Note that the failure is again the CA operator's fault.
2.4.3 Revocation - Change of CA key
As we saw above the verification of a certificate becomes more
complex once the CA is allowed to change its key. This is also true
for revocation checks as the CA may have signed the CRL using a newer
private key than the one that is within the user's PSE.
The analysis of the alternatives is as for certificate verification.
3. Data Structures
This section contains descriptions of the data structures required
for PKI management messages. Section 4 describes constraints on their
values and the sequence of events for each of the various PKI
management operations.
3.1 Overall PKI Message
All of the messages used in this specification for the purposes of
PKI management use the following structure:
PKIMessage ::= SEQUENCE {
header PKIHeader,
body PKIBody,
protection [0] PKIProtection OPTIONAL,
extraCerts [1] SEQUENCE SIZE (1..MAX) OF Certificate OPTIONAL
}
PKIMessages ::= SEQUENCE SIZE (1..MAX) OF PKIMessage
Adams & Farrell Expires Oct. 2003 [Page 21]
The PKIHeader contains information which is common to many PKI
messages.
The PKIBody contains message-specific information.
The PKIProtection, when used, contains bits that protect the PKI
message.
The extraCerts field can contain certificates that may be useful to
the recipient. For example, this can be used by a CA or RA to present
an end entity with certificates that it needs to verify its own new
certificate (if, for example, the CA that issued the end entity's
certificate is not a root CA for the end entity). Note that this
field does not necessarily contain a certification path - the
recipient may have to sort, select from, or otherwise process the
extra certificates in order to use them.
3.1.1 PKI Message Header
All PKI messages require some header information for addressing and
transaction identification. Some of this information will also be
present in a transport-specific envelope; however, if the PKI message
is protected then this information is also protected (i.e., we make
no assumption about secure transport).
The following data structure is used to contain this information:
PKIHeader ::= SEQUENCE {
pvno INTEGER { cmp1999(1), cmp2000(2) },
sender GeneralName,
-- identifies the sender
recipient GeneralName,
-- identifies the intended recipient
messageTime [0] GeneralizedTime OPTIONAL,
-- time of production of this message (used when sender
-- believes that the transport will be "suitable"; i.e.,
-- that the time will still be meaningful upon receipt)
protectionAlg [1] AlgorithmIdentifier OPTIONAL,
-- algorithm used for calculation of protection bits
senderKID [2] KeyIdentifier OPTIONAL,
recipKID [3] KeyIdentifier OPTIONAL,
-- to identify specific keys used for protection
transactionID [4] OCTET STRING OPTIONAL,
-- identifies the transaction; i.e., this will be the same in
-- corresponding request, response and confirmation messages
senderNonce [5] OCTET STRING OPTIONAL,
recipNonce [6] OCTET STRING OPTIONAL,
-- nonces used to provide replay protection, senderNonce
Adams & Farrell Expires Oct. 2003 [Page 22]
-- is inserted by the creator of this message; recipNonce
-- is a nonce previously inserted in a related message by
-- the intended recipient of this message
freeText [7] PKIFreeText OPTIONAL,
-- this may be used to indicate context-specific instructions
-- (this field is intended for human consumption)
generalInfo [8] SEQUENCE SIZE (1..MAX) OF
InfoTypeAndValue OPTIONAL
-- this may be used to convey context-specific information
-- (this field not primarily intended for human consumption)
}
PKIFreeText ::= SEQUENCE SIZE (1..MAX) OF UTF8String
-- text encoded as UTF-8 String [RFC2279] (note: each UTF8String
-- MAY include an RFC 1766/RFC 3066 language tag to indicate the
-- language of the contained text -- see [RFC2482] for details)
The pvno field is fixed (at 2) for this version of this
specification.
The sender field contains the name of the sender of the PKIMessage.
This name (in conjunction with senderKID, if supplied) should be
sufficient to indicate the key to use to verify the protection on the
message. If nothing about the sender is known to the sending entity
(e.g., in the init. req. message, where the end entity may not know
its own Distinguished Name (DN), e-mail name, IP address, etc.), then
the "sender" field MUST contain a "NULL" value; that is, the
SEQUENCE OF relative distinguished names is of zero length. In such a
case the senderKID field MUST hold an identifier (i.e., a reference
number) which indicates to the receiver the appropriate shared secret
information to use to verify the message.
The recipient field contains the name of the recipient of the
PKIMessage. This name (in conjunction with recipKID, if supplied)
should be usable to verify the protection on the message.
The protectionAlg field specifies the algorithm used to protect the
message. If no protection bits are supplied (note that PKIProtection
is OPTIONAL) then this field MUST be omitted; if protection bits are
supplied then this field MUST be supplied.
senderKID and recipKID are usable to indicate which keys have been
used to protect the message (recipKID will normally only be required
where protection of the message uses Diffie-Hellman (DH) keys).
These fields MUST be used if required to uniquely identify a key
(e.g., if more than one key is associated with a given sender name)
and SHOULD be omitted otherwise.
Adams & Farrell Expires Oct. 2003 [Page 23]
The transactionID field within the message header is to be used to
allow the recipient of a message to correlate this with an ongoing
transaction. This is needed for all transactions that consist of
more than just a single request/response pair. For transactions that
consist of a single request/response pair the rules are as follows.
A client MAY populate the transactionID field of the request. If a
server receives such a request which has the transactionID field set,
then it MUST set the transactionID field of the response to the same
value; if a server receives such request with a missing transactionID
field then it MAY set transactionID field of the response.
For transactions that consist of more than just a single
request/response pair the rules are as follows. Clients SHOULD
generate a transactionID for the first request. If a server receives
such a request which has the transactionID field set, then it MUST set
the transactionID field of the response to the same value; if a server
receives such request with a missing transactionID field then it MUST
populate transactionID field of the response with a server-generated
ID. Subsequent requests and responses MUST all set the transactionID
field to the thus established value. In all cases where a
transactionID is being used, a given client MUST NOT have more than
one transaction with the same transactionID in progress at any time
(to a given server). Servers are free to require uniqueness of the
transactionID or not, as long as they are able to correctly associate
messages with the corresponding transaction. Typically this means
that a server will require the {client, transactionID} tuple to be
unique, or even the transactionID alone to be unique if it cannot
distinguish clients based on transport level information. A server
receiving the first message of a transaction (which requires more than
a single request/response pair) that contains a transactionID that
does not allow it to meet the above constraints (typically because
the transactionID is already in use) MUST send back an
ErrorMsgContent with a PKIFailureInfo of transactionIdInUse. It is
RECOMMENDED that the clients fill the transactionID field with 128 bits
of (pseudo-) random data for the start of a transaction to reduce the
probability of having the transactionID in use at the server.
The senderNonce and recipNonce fields protect the PKIMessage against
replay attacks. The senderNonce will typically be 128 bits of
(pseudo-) random data generated by the sender, whereas the recipNonce
is copied from the senderNonce of the previous message in the
transaction.
The messageTime field contains the time at which the sender created
the message. This may be useful to allow end entities to correct/check
their local time for consistency with the time on a central system.
The freeText field may be used to send a human-readable message to
the recipient (in any number of languages). The first language used
in this sequence indicates the desired language for replies.
The generalInfo field may be used to send machine-processable
additional data to the recipient. The following generalInfo extensions
are defined and MAY be supported.
Adams & Farrell Expires Oct. 2003 [Page 24]
3.1.1.1 ImplicitConfirm
This is used by the EE to inform the CA that it does not wish to send
a certificate confirmation for issued certificates.
implicitConfirm OBJECT IDENTIFIER ::= {id-it 13}
ImplicitConfirmValue ::= NULL
If the CA grants the request to the EE, it MUST put the same extension
in the PKIHeader of the response. If the EE does not find the
extension in the response, it MUST send the certificate confirmation.
3.1.1.2 ConfirmWaitTime
This is used by the CA to inform the EE how long it intends to wait for
the certificate confirmation before revoking the certificate and
deleting the transaction.
confirmWaitTime OBJECT IDENTIFIER ::= {id-it 14}
ConfirmWaitTimeValue ::= GeneralizedTime -- time CA will wait until
3.1.2 PKI Message Body
PKIBody ::= CHOICE { -- message-specific body elements & Section ref
ir [0] CertReqMessages, --Initialization Req (3.3.1)
ip [1] CertRepMessage, --Initialization Resp (3.3.2)
cr [2] CertReqMessages, --Certification Req (3.3.3)
cp [3] CertRepMessage, --Certification Resp (3.3.4)
p10cr [4] CertificationRequest, --PKCS #10 Cert. Req. [PKCS10]
-- the PKCS #10 certification request (see [PKCS10])
popdecc [5] POPODecKeyChallContent --pop Challenge (3.2.8)
popdecr [6] POPODecKeyRespContent, --pop Response (3.2.8)
kur [7] CertReqMessages, --Key Update Request (3.3.5)
kup [8] CertRepMessage, --Key Update Response (3.3.6)
krr [9] CertReqMessages, --Key Recovery Req (3.3.7)
krp [10] KeyRecRepContent, --Key Recovery Resp (3.3.8)
rr [11] RevReqContent, --Revocation Request (3.3.9)
rp [12] RevRepContent, --Revocation Response (3.3.10)
ccr [13] CertReqMessages, --Cross-Cert. Request (3.3.11)
ccp [14] CertRepMessage, --Cross-Cert. Resp (3.3.12)
ckuann [15] CAKeyUpdAnnContent, --CA Key Update Ann. (3.3.13)
cann [16] CertAnnContent, --Certificate Ann. (3.3.14)
rann [17] RevAnnContent, --Revocation Ann. (3.3.15)
crlann [18] CRLAnnContent, --CRL Announcement (3.3.16)
pkiconf [19] PKIConfirmContent, --Confirmation (3.3.17)
nested [20] NestedMessageContent, --Nested Message (3.1.3)
genm [21] GenMsgContent, --General Message (3.3.19)
genp [22] GenRepContent, --General Response (3.3.20)
error [23] ErrorMsgContent, --Error Message (3.3.21)
certConf [24] CertConfirmContent, --Certificate confirm (3.3.18)
pollReq [25] PollReqContent, --Polling request (3.3.22)
pollRep [26] PollRepContent --Polling response (3.3.22)
}
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The specific types are described in Section 3.3 below.
3.1.3 PKI Message Protection
Some PKI messages will be protected for integrity. (Note that if an
asymmetric algorithm is used to protect a message and the relevant
public component has been certified already, then the origin of the
message can also be authenticated. On the other hand, if the public
component is uncertified then the message origin cannot be
automatically authenticated, but may be authenticated via out-of-band
means.)
When protection is applied the following structure is used:
PKIProtection ::= BIT STRING
The input to the calculation of PKIProtection is the DER encoding of
the following data structure:
ProtectedPart ::= SEQUENCE {
header PKIHeader,
body PKIBody
}
There MAY be cases in which the PKIProtection BIT STRING is
deliberately not used to protect a message (i.e., this OPTIONAL field
is omitted) because other protection, external to PKIX, will instead
be applied. Such a choice is explicitly allowed in this
specification. Examples of such external protection include PKCS #7
[PKCS7] and Security Multiparts [RFC1847] encapsulation of the
PKIMessage (or simply the PKIBody (omitting the CHOICE tag), if the
relevant PKIHeader information is securely carried in the external
mechanism). It is noted, however, that many
such external mechanisms require that the end entity already
possesses a public-key certificate, and/or a unique Distinguished
Name, and/or other such infrastructure-related information. Thus,
they may not be appropriate for initial registration, key-recovery,
or any other process with "boot-strapping" characteristics. For
those cases it may be necessary that the PKIProtection parameter be
used. In the future, if/when external mechanisms are modified to
accommodate boot-strapping scenarios, the use of PKIProtection may
become rare or non-existent.
Depending on the circumstances the PKIProtection bits may contain a
Message Authentication Code (MAC) or signature. Only the following
cases can occur:
Adams & Farrell Expires Oct. 2003 [Page 26]
- shared secret information
In this case the sender and recipient share secret information
(established via out-of-band means or from a previous PKI management
operation). PKIProtection will contain a MAC value and the
protectionAlg will be the following (see also Appendix B2):
id-PasswordBasedMac OBJECT IDENTIFIER ::= {1 2 840 113533 7 66 13}
PBMParameter ::= SEQUENCE {
salt OCTET STRING,
owf AlgorithmIdentifier,
-- AlgId for a One-Way Function (SHA-1 recommended)
iterationCount INTEGER,
-- number of times the OWF is applied
mac AlgorithmIdentifier
-- the MAC AlgId (e.g., DES-MAC, Triple-DES-MAC [PKCS11],
} -- or HMAC [RFC2104, RFC2202])
In the above protectionAlg the salt value is appended to the shared
secret input. The OWF is then applied iterationCount times, where the
salted secret is the input to the first iteration and, for each
successive iteration, the input is set to be the output of the
previous iteration. The output of the final iteration (called
"BASEKEY" for ease of reference, with a size of "H") is what is used
to form the symmetric key. If the MAC algorithm requires a K-bit key
and K <= H, then the most significant K bits of BASEKEY are used. If
K > H, then all of BASEKEY is used for the most significant H bits of
the key, OWF("1" || BASEKEY) is used for the next most significant H
bits of the key, OWF("2" || BASEKEY) is used for the next most
significant H bits of the key, and so on, until all K bits have been
derived. [Here "N" is the ASCII byte encoding the number N and "||"
represents concatenation.]
Note: it is RECOMMENDED that the fields of PBMParameter remain
constant throughout the messages of a single transaction (e.g.,
ir/ip/certConf/pkiConf) in order to reduce the overhead associated
with PasswordBasedMac computation).
- DH key pairs
Where the sender and receiver possess Diffie-Hellman certificates
with compatible DH parameters, then in order to protect the message
the end entity must generate a symmetric key based on its private DH
key value and the DH public key of the recipient of the PKI message.
PKIProtection will contain a MAC value keyed with this derived
symmetric key and the protectionAlg will be the following:
Adams & Farrell Expires Oct. 2003 [Page 27]
id-DHBasedMac OBJECT IDENTIFIER ::= {1 2 840 113533 7 66 30}
DHBMParameter ::= SEQUENCE {
owf AlgorithmIdentifier,
-- AlgId for a One-Way Function (SHA-1 recommended)
mac AlgorithmIdentifier
-- the MAC AlgId (e.g., DES-MAC, Triple-DES-MAC [PKCS11],
} -- or HMAC [RFC2104, RFC2202])
In the above protectionAlg OWF is applied to the result of the
Diffie-Hellman computation. The OWF output (called "BASEKEY" for ease
of reference, with a size of "H") is what is used to form the
symmetric key. If the MAC algorithm requires a K-bit key and K <= H,
then the most significant K bits of BASEKEY are used. If K > H, then
all of BASEKEY is used for the most significant H bits of the key,
OWF("1" || BASEKEY) is used for the next most significant H bits of
the key, OWF("2" || BASEKEY) is used for the next most significant H
bits of the key, and so on, until all K bits have been derived. [Here
"N" is the ASCII byte encoding the number N and "||" represents
concatenation.]
- signature
In this case the sender possesses a signature key pair and simply signs
the PKI message. PKIProtection will contain the signature value and
the protectionAlg will be an AlgorithmIdentifier for a digital
signature (e.g., md5WithRSAEncryption or dsaWithSha-1).
- multiple protection
In cases where an end entity sends a protected PKI message to an RA,
the RA MAY forward that message to a CA, attaching its own protection
(which MAY be a MAC or a signature, depending on the information and
certificates shared between the RA and the CA). This is accomplished
by nesting the entire message sent by the end entity within a new PKI
message. The structure used is as follows.
NestedMessageContent ::= PKIMessages
(The use of PKIMessages, a SEQUENCE OF PKIMessage, lets the RA batch
the requests of several EEs in a single new message. For simplicity,
all messages in the batch MUST be of the same type (e.g., ir)).
If the RA wishes to modify the message(s) in some way (e.g., add
particular field values or new extensions), then it MAY create its own
desired PKIBody. The original PKIMessage from the EE MAY be included
in the generalInfo field of PKIHeader (to accommodate, for example,
cases in which the CA wishes to check POP or other information on the
original EE message). The infoType to be used in this situation is
{id-it 15} (see Section 3.3.19 for the value of id-it) and the
infoValue is PKIMessages (contents MUST be in the same order as the
requests in PKIBody).
3.2 Common Data Structures
Before specifying the specific types that may be placed in a PKIBody
we define some data structures that are used in more than one case.
Adams & Farrell Expires Oct. 2003 [Page 28]
3.2.1 Requested Certificate Contents
Various PKI management messages require that the originator of the
message indicate some of the fields that are required to be present
in a certificate. The CertTemplate structure allows an end entity or
RA to specify as much as it wishes about the certificate it requires.
CertTemplate is identical to a Certificate but with all fields
optional.
Note that even if the originator completely specifies the contents of
a certificate it requires, a CA is free to modify fields within the
certificate actually issued. If the modified certificate is
unacceptable to the requester, the requester MUST send back a certConf
message which either does not include this certificate (via a
CertHash), or does include this certificate (via a CertHash) along with
a status of "rejected". See Section 3.3.18 for the definition and use
of CertHash and the certConf message.
See Appendix D and [rfc2511bis] for CertTemplate syntax.
3.2.2 Encrypted Values
Where encrypted values (restricted, in this specification, to be
either private keys or certificates) are sent in PKI messages the
EncryptedValue data structure is used.
See [rfc2511bis] for EncryptedValue syntax.
Use of this data structure requires that the creator and intended
recipient respectively be able to encrypt and decrypt. Typically,
this will mean that the sender and recipient have, or are able to
generate, a shared secret key.
If the recipient of the PKIMessage already possesses a private key
usable for decryption, then the encSymmKey field MAY contain a
session key encrypted using the recipient's public key.
3.2.3 Status codes and Failure Information for PKI messages
All response messages will include some status information. The
following values are defined.
PKIStatus ::= INTEGER {
accepted (0),
-- you got exactly what you asked for
grantedWithMods (1),
-- you got something like what you asked for; the
-- requester is responsible for ascertaining the differences
rejection (2),
-- you don't get it, more information elsewhere in the message
Adams & Farrell Expires Oct. 2003 [Page 29]
waiting (3),
-- the request body part has not yet been processed; expect to
-- hear more later (note: proper handling of this status response
-- MAY use the polling req/rep PKIMessages specified in Section
-- 3.3.22; alternatively, polling in the underlying transport
-- layer MAY have some utility in this regard)
revocationWarning (4),
-- this message contains a warning that a revocation is
-- imminent
revocationNotification (5),
-- notification that a revocation has occurred
keyUpdateWarning (6)
-- update already done for the oldCertId specified in
-- the key update request message
}
Responders may use the following syntax to provide more information
about failure cases.
PKIFailureInfo ::= BIT STRING {
-- since we can fail in more than one way!
-- More codes may be added in the future if/when required.
badAlg (0),
-- unrecognized or unsupported Algorithm Identifier
badMessageCheck (1),
-- integrity check failed (e.g., signature did not verify)
badRequest (2),
-- transaction not permitted or supported
badTime (3),
-- messageTime was not sufficiently close to the system time,
-- as defined by local policy
badCertId (4),
-- no certificate could be found matching the provided criteria
badDataFormat (5),
-- the data submitted has the wrong format
wrongAuthority (6),
-- the authority indicated in the request is different from the
-- one creating the response token
incorrectData (7),
-- the requester's data is incorrect (used for notary services)
missingTimeStamp (8),
-- when the timestamp is missing but should be there (by policy)
badPOP (9),
-- the proof-of-possession failed
certRevoked (10),
-- the certificate has already been revoked
certConfirmed (11),
-- the certificate has already been confirmed
wrongIntegrity (12),
-- invalid integrity, password based instead of signature or
-- vice versa
badRecipientNonce (13),
-- invalid recipient nonce, either missing or wrong value
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timeNotAvailable (14),
-- the TSA's time source is not available
unacceptedPolicy (15),
-- the requested TSA policy is not supported by the TSA.
unacceptedExtension (16),
-- the requested extension is not supported by the TSA.
addInfoNotAvailable (17),
-- the additional information requested could not be understood
-- or is not available
badSenderNonce (18),
-- invalid sender nonce, either missing or wrong size
badCertTemplate (19),
-- invalid certificate template or missing mandatory information
signerNotTrusted (20),
-- signer of the message unknown or not trusted
transactionIdInUse (21),
-- the transaction identifier is already in use
unsupportedVersion (22),
-- the version of the message is not supported
notAuthorized (23),
-- the sender was not authorized to make the preceding request
-- or perform the preceding action
systemUnavail (24),
-- the request cannot be handled due to system unavailability
systemFailure (25),
-- the request cannot be handled due to system failure
duplicateCertReq (26)
-- certificate cannot be issued because a duplicate certificate
-- already exists
}
PKIStatusInfo ::= SEQUENCE {
status PKIStatus,
statusString PKIFreeText OPTIONAL,
failInfo PKIFailureInfo OPTIONAL
}
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3.2.4 Certificate Identification
In order to identify particular certificates the CertId data
structure is used.
See [rfc2511bis] for CertId syntax.
3.2.5 "Out-of-band" root CA public key
Each root CA must be able to publish its current public key via some
"out-of-band" means. While such mechanisms are beyond the scope of
this document, we define data structures which can support such
mechanisms.
There are generally two methods available: either the CA directly
publishes its self-signed certificate; or this information is
available via the Directory (or equivalent) and the CA publishes a
hash of this value to allow verification of its integrity before use.
OOBCert ::= Certificate
The fields within this certificate are restricted as follows:
- The certificate MUST be self-signed (i.e., the signature must be
verifiable using the SubjectPublicKeyInfo field);
- The subject and issuer fields MUST be identical;
- If the subject field is NULL then both subjectAltNames and
issuerAltNames extensions MUST be present and have exactly the same
value;
- The values of all other extensions must be suitable for a self-
signed certificate (e.g., key identifiers for subject and issuer
must be the same).
OOBCertHash ::= SEQUENCE {
hashAlg [0] AlgorithmIdentifier OPTIONAL,
certId [1] CertId OPTIONAL,
hashVal BIT STRING
-- hashVal is calculated over the DER encoding of the
-- self-signed certificate with the identifier certID.
}
The intention of the hash value is that anyone who has securely
received the hash value (via the out-of-band means) can verify a
self-signed certificate for that CA.
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3.2.6 Archive Options
Requesters may indicate that they wish the PKI to archive a private
key value using the PKIArchiveOptions structure
See [rfc2511bis] for PKIArchiveOptions syntax.
3.2.7 Publication Information
Requesters may indicate that they wish the PKI to publish a
certificate using the PKIPublicationInfo structure.
See [rfc2511bis] for PKIPublicationInfo syntax.
3.2.8 Proof-of-Possession Structures
If the certification request is for a signing key pair (i.e., a
request for a verification certificate), then the proof of possession
of the private signing key is demonstrated through use of the
POPOSigningKey structure.
See Appendix D and [rfc2511bis] for POPOSigningKey syntax, but note
that POPOSigningKeyInput has the following semantic stipulations in
this specification.
POPOSigningKeyInput ::= SEQUENCE {
authInfo CHOICE {
sender [0] GeneralName,
-- from PKIHeader (used only if an authenticated identity
-- has been established for the sender (e.g., a DN from a
-- previously-issued and currently-valid certificate))
publicKeyMAC PKMACValue
-- used if no authenticated GeneralName currently exists for
-- the sender; publicKeyMAC contains a password-based MAC
-- (using the protectionAlg AlgId from PKIHeader) on the
-- DER-encoded value of publicKey
},
publicKey SubjectPublicKeyInfo -- from CertTemplate
}
On the other hand, if the certification request is for an encryption
key pair (i.e., a request for an encryption certificate), then the
proof of possession of the private decryption key may be demonstrated
in one of three ways.
1) By the inclusion of the private key (encrypted) in the
CertRequest (in the thisMessage field of POPOPrivKey (see
Appendix D) or in the PKIArchiveOptions control structure,
depending upon whether or not archival of the private key
is also desired).
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2) By having the CA return not the certificate, but an encrypted
certificate (i.e., the certificate encrypted under a randomly-
generated symmetric key, and the symmetric key encrypted under
the public key for which the certification request is being
made) -- this is the "indirect" method mentioned previously in
Section 2.3.2. The end entity proves knowledge of the private
decryption key to the CA by providing the correct CertHash for
this certificate in the certConf message. This demonstrates POP
because the EE can only compute the correct CertHash if it is
able to recover the certificate, and it can only recover the
certificate if it is able to decrypt the symmetric key using the
required private key. Clearly, for this to work, the CA MUST NOT
publish the certificate until the certConf message arrives (when
certHash is to be used to demonstrate POP). See Section 3.3.18
for further details.
3) By having the end entity engage in a challenge-response
protocol (using the messages POPODecKeyChall and
POPODecKeyResp; see below) between CertReqMessages and
CertRepMessage -- this is the "direct" method mentioned
previously in Section 2.3.2. [This method would typically be
used in an environment in which an RA verifies POP and then
makes a certification request to the CA on behalf of the end
entity. In such a scenario, the CA trusts the RA to have done
POP correctly before the RA requests a certificate for the end
entity.] The complete protocol then looks as follows (note
that req' does not necessarily encapsulate req as a nested
message):
EE RA CA
---- req ---->
<--- chall ---
---- resp --->
---- req' --->
<--- rep -----
---- conf --->
<--- ack -----
<--- rep -----
---- conf --->
<--- ack -----
This protocol is obviously much longer than the 3-way exchange given
in choice (2) above, but allows a local Registration Authority to be
involved and has the property that the certificate itself is not
actually created until the proof of possession is complete. In some
environments a different order of the above messages may be required,
such as the following (this may be determined by policy):
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EE RA CA
---- req ---->
<--- chall ---
---- resp --->
---- req' --->
<--- rep -----
<--- rep -----
---- conf --->
---- conf --->
<--- ack -----
<--- ack -----
If the cert. request is for a key agreement key (KAK) pair, then the
POP can use any of the 3 ways described above for enc. key pairs,
with the following changes: (1) the parenthetical text of bullet 2)
is replaced with "(i.e., the certificate encrypted under the
symmetric key derived from the CA's private KAK and the public key
for which the certification request is being made)"; (2) the first
parenthetical text of the challenge field of "Challenge" below is
replaced with "(using PreferredSymmAlg (see Section 3.3.19.4 and
Appendix C5) and a symmetric key derived from the CA's private KAK
and the public key for which the certification request is being
made)". Alternatively, the POP can use the POPOSigningKey structure
given in [rfc2511bis] (where the alg field is DHBasedMAC and the
signature field is the MAC) as a fourth alternative for demonstrating
POP if the CA already has a D-H certificate that is known to the EE.
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The challenge-response messages for proof of possession of a private
decryption key are specified as follows (see [MvOV97, p.404] for
details). Note that this challenge-response exchange is associated
with the preceding cert. request message (and subsequent cert.
response and confirmation messages) by the transactionID used in the
PKIHeader and by the protection (MACing or signing) applied to the
PKIMessage.
POPODecKeyChallContent ::= SEQUENCE OF Challenge
-- One Challenge per encryption key certification request (in the
-- same order as these requests appear in CertReqMessages).
Challenge ::= SEQUENCE {
owf AlgorithmIdentifier OPTIONAL,
-- MUST be present in the first Challenge; MAY be omitted in any
-- subsequent Challenge in POPODecKeyChallContent (if omitted,
-- then the owf used in the immediately preceding Challenge is
-- to be used).
witness OCTET STRING,
-- the result of applying the one-way function (owf) to a
-- randomly-generated INTEGER, A. [Note that a different
-- INTEGER MUST be used for each Challenge.]
challenge OCTET STRING
-- the encryption (under the public key for which the cert.
-- request is being made) of Rand, where Rand is specified as
-- Rand ::= SEQUENCE {
-- int INTEGER,
-- - the randomly-generated INTEGER A (above)
-- sender GeneralName
-- - the sender's name (as included in PKIHeader)
-- }
}
Note that the size of Rand needs to be appropriate for encryption
under the public key of the requester. Given that "int" will
typically not be longer than 64 bits, this leaves well over 100 bytes
of room for the "sender" field when the modulus is 1024 bits. If, in
some environment, names are so long that they cannot fit (e.g., very
long DNs), then whatever portion will fit should be used (as long as
it includes at least the common name, and as long as the receiver is
able to deal meaningfully with the abbreviation).
POPODecKeyRespContent ::= SEQUENCE OF INTEGER
-- One INTEGER per encryption key certification request (in the
-- same order as these requests appear in CertReqMessages). The
-- retrieved INTEGER A (above) is returned to the sender of the
-- corresponding Challenge.
The text in this section provides several options with respect to POP
techniques. Using "SK" for "signing key", "EK" for "encryption key",
and "KAK" for "key agreement key", the techniques may be summarized as
follows:
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RAVerified;
SKPOP;
EKPOPThisMessage;
KAKPOPThisMessage;
KAKPOPThisMessageDHMAC;
EKPOPEncryptedCert;
KAKPOPEncryptedCert;
EKPOPChallengeResp; and
KAKPOPChallengeResp.
Given this array of options, it is natural to ask how an end entity
can know what is supported by the CA/RA (i.e., which options it may
use when requesting certificates). The following guidelines should
clarify this situation for EE implementers.
RAVerified. This is not an EE decision; the RA uses this if and only
if it has verified POP before forwarding the request on to the CA, so
it is not possible for the EE to choose this technique.
SKPOP. If the EE has a signing key pair, this is the only POP method
specified for use in the request for a corresponding certificate.
EKPOPThisMessage and KAKPOPThisMessage. It is an EE decision whether
or not to give up its private key to the CA/RA. If the EE decides to
reveal its key, then these are the only POP methods available in this
specification to achieve this (and the key pair type will determine
which of these two methods to use).
KAKPOPThisMessageDHMAC. The EE can only use this method if (1) the CA
has a DH certificate available for this purpose, and (2) the EE already
has a copy of this certificate. If both these conditions hold, then
this technique is clearly supported and may be used by the EE, if
desired.
EKPOPEncryptedCert, KAKPOPEncryptedCert, EKPOPChallengeResp,
KAKPOPChallengeResp. The EE picks one of these (in the
subsequentMessage field) in the request message, depending upon
preference and key pair type. The EE is not doing POP at this point;
it is simply indicating which method it wants to use. Therefore, if the
CA/RA replies with a "badPOP" error, the EE can re-request using the
other POP method chosen in subsequentMessage. Note, however, that this
specification encourages the use of the EncryptedCert choice and,
furthermore, says that the challenge-response would typically be used
when an RA is involved and doing POP verification. Thus, the EE should
be able to make an intelligent decision regarding which of these POP
methods to choose in the request message.
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3.3 Operation-Specific Data Structures
3.3.1 Initialization Request
An Initialization request message contains as the PKIBody a
CertReqMessages data structure which specifies the requested
certificate(s). Typically, SubjectPublicKeyInfo, KeyId, and Validity
are the template fields which may be supplied for each certificate
requested (see Appendix B profiles for further information). This
message is intended to be used for entities first initializing into
the PKI.
See Appendix D and [rfc2511bis] for CertReqMessages syntax.
3.3.2 Initialization Response
An Initialization response message contains as the PKIBody an
CertRepMessage data structure which has for each certificate
requested a PKIStatusInfo field, a subject certificate, and possibly
a private key (normally encrypted with a session key, which is itself
encrypted with the protocolEncrKey).
See Section 3.3.4 for CertRepMessage syntax. Note that if the PKI
Message Protection is "shared secret information" (see Section
3.1.3), then any certificate transported in the caPubs field may be
directly trusted as a root CA certificate by the initiator.
3.3.3 Certification Request
A Certification request message contains as the PKIBody
a CertReqMessages data structure which specifies the requested
certificates. This message is intended to be used for existing PKI
entities who wish to obtain additional certificates.
See Appendix D and [rfc2511bis] for CertReqMessages syntax.
Alternatively, the PKIBody MAY be a CertificationRequest (this
structure is fully specified by the ASN.1 structure
CertificationRequest given in [PKCS10]). This structure may be
required for certificate requests for signing key pairs when
interoperation with legacy systems is desired, but its use is
strongly discouraged whenever not absolutely necessary.
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3.3.4 Certification Response
A Certification response message contains as the PKIBody a
CertRepMessage data structure which has a status value for each
certificate requested, and optionally has a CA public key, failure
information, a subject certificate, and an encrypted private key.
CertRepMessage ::= SEQUENCE {
caPubs [1] SEQUENCE SIZE (1..MAX) OF Certificate OPTIONAL,
response SEQUENCE OF CertResponse
}
CertResponse ::= SEQUENCE {
certReqId INTEGER,
-- to match this response with corresponding request (a value
-- of -1 is to be used if certReqId is not specified in the
-- corresponding request)
status PKIStatusInfo,
certifiedKeyPair CertifiedKeyPair OPTIONAL,
rspInfo OCTET STRING OPTIONAL
-- analogous to the id-regInfo-utf8Pairs string defined
-- for regInfo in CertReqMsg [rfc2511bis]
}
CertifiedKeyPair ::= SEQUENCE {
certOrEncCert CertOrEncCert,
privateKey [0] EncryptedValue OPTIONAL,
-- see [rfc2511bis] for comment on encoding
publicationInfo [1] PKIPublicationInfo OPTIONAL
}
CertOrEncCert ::= CHOICE {
certificate [0] Certificate,
encryptedCert [1] EncryptedValue
}
Only one of the failInfo (in PKIStatusInfo) and certificate (in
CertifiedKeyPair) fields can be present in each CertResponse
(depending on the status). For some status values (e.g., waiting)
neither of the optional fields will be present.
Given an EncryptedCert and the relevant decryption key the
certificate may be obtained. The purpose of this is to allow a CA to
return the value of a certificate, but with the constraint that only
the intended recipient can obtain the actual certificate. The benefit
of this approach is that a CA may reply with a certificate even in
the absence of a proof that the requester is the end entity which can
use the relevant private key (note that the proof is not obtained
Adams & Farrell Expires Oct. 2003 [Page 39]
until the certConf message is received by the CA). Thus the CA will
not have to revoke that certificate in the event that something goes
wrong with the proof of possession (but MAY do so anyway, depending
upon policy).
3.3.5 Key update request content
For key update requests the CertReqMessages syntax is used.
Typically, SubjectPublicKeyInfo, KeyId, and Validity are the template
fields which may be supplied for each key to be updated. This
message is intended to be used to request updates to existing (non-
revoked and non-expired) certificates (therefore, it is sometimes
referred to as a "Certificate Update" operation). An update is a
replacement certificate containing either a new subject public key or
the current subject public key (although the latter practice may not
be appropriate for some environments).
See Appendix D and [rfc2511bis] for CertReqMessages syntax.
3.3.6 Key Update response content
For key update responses the CertRepMessage syntax is used. The
response is identical to the initialization response.
See Section 3.3.4 for CertRepMessage syntax.
3.3.7 Key Recovery Request content
For key recovery requests the syntax used is identical to the
initialization request CertReqMessages. Typically,
SubjectPublicKeyInfo and KeyId are the template fields which may be
used to supply a signature public key for which a certificate is
required (see Appendix B profiles for further information).
See Appendix D and [rfc2511bis] for CertReqMessages syntax. Note that
if a key history is required, the requester must supply a Protocol
Encryption Key control in the request message.
3.3.8 Key recovery response content
For key recovery responses the following syntax is used. For some
status values (e.g., waiting) none of the optional fields will be
present.
KeyRecRepContent ::= SEQUENCE {
status PKIStatusInfo,
newSigCert [0] Certificate OPTIONAL,
caCerts [1] SEQUENCE SIZE (1..MAX) OF
Certificate OPTIONAL,
keyPairHist [2] SEQUENCE SIZE (1..MAX) OF
CertifiedKeyPair OPTIONAL
}
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3.3.9 Revocation Request Content
When requesting revocation of a certificate (or several certificates)
the following data structure is used. The name of the requester is
present in the PKIHeader structure.
RevReqContent ::= SEQUENCE OF RevDetails
RevDetails ::= SEQUENCE {
certDetails CertTemplate,
-- allows requester to specify as much as they can about
-- the cert. for which revocation is requested
-- (e.g., for cases in which serialNumber is not available)
crlEntryDetails Extensions OPTIONAL
-- requested crlEntryExtensions
}
3.3.10 Revocation Response Content
The response to the above message. If produced, this is sent to the
requester of the revocation. (A separate revocation announcement
message MAY be sent to the subject of the certificate for which
revocation was requested.)
RevRepContent ::= SEQUENCE {
status SEQUENCE SIZE (1..MAX) OF PKIStatusInfo,
-- in same order as was sent in RevReqContent
revCerts [0] SEQUENCE SIZE (1..MAX) OF CertId OPTIONAL,
-- IDs for which revocation was requested (same order as status)
crls [1] SEQUENCE SIZE (1..MAX) OF CertificateList OPTIONAL
-- the resulting CRLs (there may be more than one)
}
3.3.11 Cross certification request content
Cross certification requests use the same syntax (CertReqMessages) as
for normal certification requests with the restriction that the key
pair MUST have been generated by the requesting CA and the private
key MUST NOT be sent to the responding CA. This request MAY also be
used by subordinate CAs to get their certificates signed by the parent
CA.
See Appendix D and [rfc2511bis] for CertReqMessages syntax.
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3.3.12 Cross certification response content
Cross certification responses use the same syntax (CertRepMessage) as
for normal certification responses with the restriction that no
encrypted private key can be sent.
See Section 3.3.4 for CertRepMessage syntax.
3.3.13 CA Key Update Announcement content
When a CA updates its own key pair the following data structure MAY
be used to announce this event.
CAKeyUpdAnnContent ::= SEQUENCE {
oldWithNew Certificate, -- old pub signed with new priv
newWithOld Certificate, -- new pub signed with old priv
newWithNew Certificate -- new pub signed with new priv
}
3.3.14 Certificate Announcement
This structure MAY be used to announce the existence of certificates.
Note that this message is intended to be used for those cases (if
any) where there is no pre-existing method for publication of
certificates; it is not intended to be used where, for example, X.500
is the method for publication of certificates.
CertAnnContent ::= Certificate
3.3.15 Revocation Announcement
When a CA has revoked, or is about to revoke, a particular
certificate it MAY issue an announcement of this (possibly upcoming)
event.
RevAnnContent ::= SEQUENCE {
status PKIStatus,
certId CertId,
willBeRevokedAt GeneralizedTime,
badSinceDate GeneralizedTime,
crlDetails Extensions OPTIONAL
-- extra CRL details(e.g., crl number, reason, location, etc.)
}
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A CA MAY use such an announcement to warn (or notify) a subject that
its certificate is about to be (or has been) revoked. This would
typically be used where the request for revocation did not come from
the subject concerned.
The willBeRevokedAt field contains the time at which a new entry will
be added to the relevant CRLs.
3.3.16 CRL Announcement
When a CA issues a new CRL (or set of CRLs) the following data
structure MAY be used to announce this event.
CRLAnnContent ::= SEQUENCE OF CertificateList
3.3.17 PKI Confirmation content
This data structure is used in the protocol exchange as the final
PKIMessage. Its content is the same in all cases - actually there is
no content since the PKIHeader carries all the required information.
PKIConfirmContent ::= NULL
Use of this message for certificate confirmation is NOT RECOMMENDED;
certConf SHOULD be used instead. The recipient on receiving a
PKIConfirm for a certificate response MAY treat it as a certConf
with all certificates being accepted.
3.3.18 Certificate Confirmation content
This data structure is used by the client to send a confirmation to the
CA/RA to accept or reject certificates.
CertConfirmContent ::= SEQUENCE OF CertStatus
CertStatus ::= SEQUENCE {
certHash OCTET STRING,
-- the hash of the certificate, using the same hash algorithm
-- as is used to create and verify the certificate signature
certReqId INTEGER,
-- to match this confirmation with the corresponding req/rep
statusInfo PKIStatusInfo OPTIONAL
}
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For any particular CertStatus, omission of the statusInfo field
indicates ACCEPTANCE of the specified certificate. Alternatively,
explicit status details (with respect to acceptance or rejection) MAY
be provided in the statusInfo field, perhaps for auditing purposes at
the CA/RA.
Within CertConfirmContent, omission of a CertStatus structure
corresponding to a certificate supplied in the previous response
message indicates REJECTION of the certificate. Thus, an empty
CertConfirmContent (a zero-length SEQUENCE) MAY be used to indicate
rejection of all supplied certificates. See Section 3.2.8, item (2),
for a discussion of the certHash field with respect to
proof-of-possession.
3.3.19 PKI General Message content
InfoTypeAndValue ::= SEQUENCE {
infoType OBJECT IDENTIFIER,
infoValue ANY DEFINED BY infoType OPTIONAL
}
-- Example InfoTypeAndValue contents include, but are not limited to
-- the following (see subsequent subsections for further details and
-- Appendix F for exact syntax):
--
-- { CAProtEncCert = {id-it 1}, Certificate }
-- { SignKeyPairTypes = {id-it 2}, SEQUENCE OF AlgorithmIdentifier }
-- { EncKeyPairTypes = {id-it 3}, SEQUENCE OF AlgorithmIdentifier }
-- { PreferredSymmAlg = {id-it 4}, AlgorithmIdentifier }
-- { CAKeyUpdateInfo = {id-it 5}, CAKeyUpdAnnContent }
-- { CurrentCRL = {id-it 6}, CertificateList }
--
-- where {id-it} = {id-pkix 4} = {1 3 6 1 5 5 7 4}
-- This construct MAY also be used to define new PKIX Certificate
-- Management Protocol request and response messages, or general-
-- purpose (e.g., announcement) messages for future needs or for
-- specific environments.
GenMsgContent ::= SEQUENCE OF InfoTypeAndValue
-- May be sent by EE, RA, or CA (depending on message content).
-- The OPTIONAL infoValue parameter of InfoTypeAndValue will typically
-- be omitted in GenMsg for some of the examples given above (i.e., it
-- will be used only in the corresponding GenRep message). The receiver
-- is free to ignore any contained OBJ. IDs that it does not recognize.
-- If sent from EE to CA, the empty set indicates that the CA may send
-- any/all information that it wishes.
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3.3.19.1 CA Protocol Encryption Certificate
This MAY be used by the EE to get from the CA a certificate to use to
protect sensitive information during the protocol.
GenMsg: {id-it 1}, <absent>
GenRep: {id-it 1}, Certificate | <absent>
EEs MUST ensure that the correct certificate is used for this purpose.
3.3.19.2 Signing Key Pair Types
This MAY be used by the EE to get the list of signature algorithms
(e.g., RSA, DSA) whose subject public key values the CA is willing to
certify. Note that for the purposes of this exchange, rsaEncryption
and rsaWithSHA1, for example, are considered to be equivalent; the
question being asked is, "Is the CA willing to certify an RSA public
key?"
GenMsg: {id-it 2}, <absent>
GenRep: {id-it 2}, SEQUENCE SIZE (1..MAX) OF AlgorithmIdentifier
3.3.19.3 Encryption/Key Agreement Key Pair Types
This MAY be used by the client to get the list of encryption/key
agreement algorithms whose subject public key values the CA is willing
to certify.
GenMsg: {id-it 3}, <absent>
GenRep: {id-it 3}, SEQUENCE SIZE (1..MAX) OF AlgorithmIdentifier
3.3.19.4 Preferred Symmetric Algorithm
This MAY be used by the client to get the CA-preferred symmetric
encryption algorithm for any confidential information that needs to
be exchanged between the EE and the CA (for example, if the EE wants
to send its private decryption key to the CA for archival purposes).
GenMsg: {id-it 4}, <absent>
GenRep: {id-it 4}, AlgorithmIdentifier
3.3.19.5 Updated CA Key Pair
This MAY be used by the CA to announce a CA key update event.
GenMsg: {id-it 5}, CAKeyUpdAnnContent
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3.3.19.6 CRL
This MAY be used by the client to get a copy of the latest CRL.
GenMsg: {id-it 6}, <absent>
GenRep: {id-it 6}, CertificateList
3.3.19.7 Unsupported Object Identifiers
This is used by the server to return a list of object identifiers that
it does not recognize or support from the list submitted by the client.
GenRep: {id-it 7}, SEQUENCE SIZE (1..MAX) OF OBJECT IDENTIFIER
3.3.19.8 Key Pair Parameters
This MAY be used by the EE to request the domain parameters to use
for generating the key pair for certain public-key algorithms. It can
be used, for example, to request the appropriate P, Q and G to generate
the DH/DSA key, or to request a set of well-known elliptic curves.
GenMsg: {id-it 10}, OBJECT IDENTIFIER -- (Algorithm object-id)
GenRep: {id-it 11}, AlgorithmIdentifier | <absent>
An absent infoValue in the GenRep indicates that the algorithm
specified in GenMsg is not supported.
EEs MUST ensure that the parameters are acceptable to it and that the
GenRep message is authenticated (to avoid substitution attacks).
3.3.19.9 Revocation Passphrase
This MAY be used by the EE to send a passphrase to a CA/RA for the
purpose of authenticating a later revocation request (in the case that
the appropriate signing private key is no longer available to
authenticate the request). See Appendix E for further details on the
use of this mechanism.
GenMsg: {id-it 12}, EncryptedValue
GenRep: {id-it 12}, <absent>
3.3.19.10 ImplicitConfirm
See Section 3.1.1.1 for the definition and use of {id-it 13}.
3.3.19.11 ConfirmWaitTime
See Section 3.1.1.2 for the definition and use of {id-it 14}.
3.3.19.12 Original PKIMessage
See Section 3.1.3 for the definition and use of {id-it 15}.
3.3.19.13 Supported Lanuage Tags
This MAY be used to determine the appropriate language tag to use in
subsequent messages. The sender sends its list of supported languages
(in order, most preferred to least); the receiver returns the one it
wishes to use. (Note: each UTF8String MUST include a language tag.)
If none of the offered tags are supported, an error MUST be returned.
GenMsg: {id-it 16}, SEQUENCE SIZE (1..MAX) OF UTF8String
GenRep: {id-it 16}, SEQUENCE SIZE (1) OF UTF8String
Adams & Farrell Expires Oct. 2003 [Page 46]
3.3.20 PKI General Response content
GenRepContent ::= SEQUENCE OF InfoTypeAndValue
-- Receiver MAY ignore any contained OIDs that it does not recognize.
Example GenRep that MAY be supported include those listed in the
subsections of 3.3.19.
3.3.21 Error Message content
This data structure MAY be used by EE, CA, or RA to convey error info.
ErrorMsgContent ::= SEQUENCE {
pKIStatusInfo PKIStatusInfo,
errorCode INTEGER OPTIONAL,
-- implementation-specific error codes
errorDetails PKIFreeText OPTIONAL
-- implementation-specific error details
}
This message MAY be generated at any time during a PKI transaction.
If the client sends this request the server MUST respond with a
PKIConfirm response, or another ErrorMsg if any part of the header
is not valid. Both sides MUST treat this message as the end of the
transaction (if a transaction is in progress).
If protection is desired on the message, the client MUST protect it
using the same technique (i.e., signature or MAC) as the starting
message of the transaction. The CA MUST always sign it with a
signature key.
3.3.22 Polling Request and Response
This pair of messages is intended to handle scenarios in which the
client needs to poll the server in order to determine the status of an
outstanding ir, cr, or kur transaction (i.e., when the "waiting"
PKIStatus has been received).
PollReqContent ::= SEQUENCE OF SEQUENCE {
certReqId INTEGER }
PollRepContent ::= SEQUENCE OF SEQUENCE {
certReqId INTEGER,
checkAfter INTEGER, -- time in seconds
reason PKIFreeText OPTIONAL }
The following clauses describe when polling messages are used, and how
they are used. It is assumed that multiple certConf messages can be
sent during transactions. There will be one sent in response to each
ip, cp, or kup containing a CertStatus for an approved certificate.
1. In response to an ip, cp, or kup message, an EE will send a certConf
for all approved certificates and, following the ack, a pollReq for all
pending certificates.
Adams & Farrell Expires Oct. 2003 [Page 47]
2. In respose to a pollReq, a CA/RA will return an ip, cp, or kup if
one or more of the pending certificates is ready; otherwise, it will
return a pollRep.
3. If the EE receives a pollRep, it will wait for at least as long as
the checkAfter value before sending another pollReq.
4. If an ip, cp, or kup is received in response to a pollReq, then it
will be treated in the same way as the initial response.
START
|
|
\/
Send ir
|
| ip
|
\/
Check status
of returned <-----------------------------+
certs |
| |
+----------------------------->|<-----------------------+ |
| | | |
| | | |
| (approved) \/ (waiting) | |
Add to <---------------- Check CertResponse -----------> Add to |
conf list for each certificate pending list |
/\ |
/ \ |
(conf list) / \ (empty conf list) |
/ \ ip |
/ \ +----------------------+
/ \ |
(empty pending list) / \ | pRep
END <--------- Send certConf Send pReq------------>Wait
| /\ /\ |
| | | |
+-----------------+ +---------------+
(pending list)
In the following exchange, the end entity is enrolling for two
certificates in one request.
Step End Entity PKI
--------------------------------------------------------------------
1 Format ir
2 -> ir ->
3 Handle ir
4 Manual intervention is
required for both certs.
5 <- ip <-
Adams & Farrell Expires Oct. 2003 [Page 48]
6 Process ip
7 Format pReq
8 -> pReq ->
9 Check status of cert requests
10 Certificates not ready
11 Format pRep
12 <- pRep <-
13 Wait
14 Format pReq
15 -> pReq ->
16 Check status of cert requests
17 One certificate is ready
18 Format ip
19 <- ip <-
20 Handle ip
21 Format certConf
22 -> certConf ->
23 Handle certConf
24 Format ack
25 <- pkiConf <-
26 Format pReq
27 -> pReq ->
28 Check status of certificate
29 Certificate is ready
30 Format ip
31 <- ip <-
31 Handle ip
32 Format certConf
33 -> certConf ->
34 Handle certConf
35 Format ack
36 <- pkiConf <-
4. Mandatory PKI Management functions
Some of the PKI management functions outlined in Section 1 above are
described in this section.
This section deals with functions that are "mandatory" in the sense
that all end entity and CA/RA implementations MUST be able to provide
the functionality described. This part is effectively the
profile of the PKI management functionality that MUST be supported.
Note, however, that the management functions described in this section
do not need to be accomplished using the PKI messages defined in
Section 3 if alternate means are suitable for a given environment (see
Appendix B for profiles of the PKIMessages that MUST be supported).
4.1 Root CA initialization
[See Section 1.2.2 for this document's definition of "root CA".]
A newly created root CA must produce a "self-certificate" which is a
Certificate structure with the profile defined for the "newWithNew"
certificate issued following a root CA key update.
Adams & Farrell Expires Oct. 2003 [Page 49]
In order to make the CA's self certificate useful to end entities
that do not acquire the self certificate via "out-of-band" means, the
CA must also produce a fingerprint for its certificate. End entities
that acquire this fingerprint securely via some "out-of-band" means
can then verify the CA's self-certificate and hence the other
attributes contained therein.
The data structure used to carry the fingerprint is the OOBCertHash.
4.2 Root CA key update
CA keys (as all other keys) have a finite lifetime and will have to
be updated on a periodic basis. The certificates NewWithNew,
NewWithOld, and OldWithNew (see Section 2.4.1) MAY be issued by the CA
to aid existing end entities who hold the current self-signed CA
certificate (OldWithOld) to transition securely to the new self-
signed CA certificate (NewWithNew), and to aid new end entities who
will hold NewWithNew to acquire OldWithOld securely for verification
of existing data.
4.3 Subordinate CA initialization
[See Section 1.2.2 for this document's definition of "subordinate
CA".]
From the perspective of PKI management protocols the initialization
of a subordinate CA is the same as the initialization of an end
entity. The only difference is that the subordinate CA must also
produce an initial revocation list.
4.4 CRL production
Before issuing any certificates a newly established CA (which issues
CRLs) must produce "empty" versions of each CRL which is to be
periodically produced.
4.5 PKI information request
When a PKI entity (CA, RA, or EE) wishes to acquire information about
the current status of a CA it MAY send that CA a request for such
information.
The CA must respond to the request by providing (at least) all of the
information requested by the requester. If some of the information
cannot be provided then an error must be conveyed to the requester.
If PKIMessages are used to request and supply this PKI information,
then the request MUST be the GenMsg message, the response MUST be the
GenRep message, and the error MUST be the Error message. These
messages are protected using a MAC based on shared secret information
(i.e., PasswordBasedMAC) or any other authenticated means (if the end
entity has an existing certificate).
Adams & Farrell Expires Oct. 2003 [Page 50]
4.6 Cross certification
The requester CA is the CA that will become the subject of the
cross-certificate; the responder CA will become the issuer of the
cross-certificate.
The requester CA must be "up and running" before initiating the
cross-certification operation.
4.6.1 One-way request-response scheme:
The cross-certification scheme is essentially a one way operation;
that is, when successful, this operation results in the creation of
one new cross-certificate. If the requirement is that cross-
certificates be created in "both directions" then each CA in turn
must initiate a cross-certification operation (or use another
scheme).
This scheme is suitable where the two CAs in question can already
verify each other's signatures (they have some common points of
trust) or where there is an out-of-band verification of the origin of
the certification request.
Detailed Description:
Cross certification is initiated at one CA known as the responder.
The CA administrator for the responder identifies the CA it wants to
cross certify and the responder CA equipment generates an
authorization code. The responder CA administrator passes this
authorization code by out-of-band means to the requester CA
administrator. The requester CA administrator enters the
authorization code at the requester CA in order to initiate the on-
line exchange.
The authorization code is used for authentication and integrity
purposes. This is done by generating a symmetric key based on the
authorization code and using the symmetric key for generating Message
Authentication Codes (MACs) on all messages exchanged. (Authentication
may alternatively be done using signatures instead of MACs, if the CAs
are able to retrieve and validate the required public keys by some
means, such as an out-of-band hash comparison.)
The requester CA initiates the exchange by generating a cross-
certification request (ccr) with a fresh random number(requester random
number). The requester CA then sends to the responder CA the ccr
message. The fields in this message are protected from modification
with a MAC based on the authorization code.
Upon receipt of the ccr message, the responder CA validates the message
and the MAC, saves the requester random number, and generates its own
random number (responder random number). It then
Adams & Farrell Expires Oct. 2003 [Page 51]
generates (and archives, if desired) a new requester certificate that
contains the requester CA public key and is signed with the responder
CA signature private key. The responder CA responds with the cross
certification response (ccp) message. The fields in this message are
protected from modification with a MAC based on the authorization code.
Upon receipt of the ccp message, the requester CA validates the message
(including the received random numbers) and the MAC. The requester CA
responds with the certConf message. The fields in this message are
protected from modification with a MAC based on the authorization
code. The requester CA MAY write the requester certificate to the
Repository as an aid to later certificate path construction.
Upon receipt of the certConf message, the responder CA validates the
message and the MAC, and sends back an acknowledgment using the
PKIConfirm message. It MAY also publish the requester certificate as
an aid to later path construction.
Notes:
1. The ccr message must contain a "complete" certification request,
that is, all fields except the serial number (including, e.g., a
BasicConstraints extension) must be specified by the requester CA.
2. The ccp message SHOULD contain the verification certificate of the
responder CA - if present, the requester CA must then verify this
certificate (for example, via the "out-of-band" mechanism).
(A simpler, non-interactive model of cross-certification may also be
envisioned, in which the issuing CA acquires the subject CA's public
key from some repository, verifies it via some out-of-band mechanism,
and creates and publishes the cross-certificate without the subject
CA's explicit involvement. This model may be perfectly legitimate for
many environments, but since it does not require any protocol message
exchanges, its detailed description is outside the scope of this
specification.)
Adams & Farrell Expires Oct. 2003 [Page 52]
4.7 End entity initialization
As with CAs, end entities must be initialized. Initialization of end
entities requires at least two steps:
- acquisition of PKI information
- out-of-band verification of one root-CA public key
(other possible steps include the retrieval of trust condition
information and/or out-of-band verification of other CA public keys).
4.7.1 Acquisition of PKI information
The information REQUIRED is:
- the current root-CA public key
- (if the certifying CA is not a root-CA) the certification path
from the root CA to the certifying CA together with appropriate
revocation lists
- the algorithms and algorithm parameters which the certifying CA
supports for each relevant usage
Adams & Farrell Expires Oct. 2003 [Page 53]
Additional information could be required (e.g., supported extensions
or CA policy information) in order to produce a certification request
which will be successful. However, for simplicity we do not mandate
that the end entity acquires this information via the PKI messages.
The end result is simply that some certification requests may fail
(e.g., if the end entity wants to generate its own encryption key but
the CA doesn't allow that).
The required information MAY be acquired as described in Section 4.5.
4.7.2 Out-of-Band Verification of Root-CA Key
An end entity must securely possess the public key of its root CA.
One method to achieve this is to provide the end entity with the CA's
self-certificate fingerprint via some secure "out-of-band" means. The
end entity can then securely use the CA's self-certificate.
See Section 4.1 for further details.
4.8 Certificate Request
An initialized end entity MAY request an additional certificate at any
time (for any purpose). This request will be made using the
certification request (cr) message. If the end entity already
possesses a signing key pair (with a corresponding verification
certificate), then this cr message will typically be protected by the
entity's digital signature. The CA returns the new certificate (if
the request is successful) in a CertRepMessage.
4.9 Key Update
When a key pair is due to expire the relevant end entity MAY request
a key update - that is, it MAY request that the CA issue a new
certificate for a new key pair (or, in certain circumstances, a new
certificate for the same key pair). The request is made using a key
update request (kur) message (referred to, in some environments, as a
"Certificate Update" operation). If the end entity already possesses
a signing key pair (with a corresponding verification certificate),
then this message will typically be protected by the entity's digital
signature. The CA returns the new certificate (if the request is
successful) in a key update response (kup) message, which is
syntactically identical to a CertRepMessage.
Adams & Farrell Expires Oct. 2003 [Page 54]
5. Version Negotiation
This section defines version negotiation used to support older
protocols between client and servers.
If a client knows the protocol version(s) supported by the server
(e.g. from a previous PKIMessage exchange or via some out-of-band
means) then it MUST send a PKIMessage with the highest version
supported by both it and the server. If a client does not know what
version(s) the server supports then it MUST send a PKIMessage using
the highest version it supports.
If a server receives a message with a version that it supports, then
the version of the response message MUST be the same as the received
version. If a server receives a message with a version higher or
lower than it supports, then it MUST send back an ErrorMsg
with the unsupportedVersion bit set (in the failureInfo field of the
pKIStatusInfo). If the received version is higher than the highest
supported version then the version in the error message MUST be the
highest version the server supports; if the received version is lower
than the lowest supported version then the version in the error
message MUST be the lowest version the server supports.
If a client gets back an ErrorMsgContent with the unsupportedVersion
bit set and a version it supports, then it MAY retry the request with
that version.
5.1 Supporting RFC 2510 implementations
RFC 2510 did not specify the behaviour of implementations receiving
versions they did not understand since there was only one version in
existence. With the introduction of the present revision of the
specification, the following versioning behaviour is recommended.
5.1.1 Clients talking to RFC 2510 servers
If, after sending a cmp2000 message, a client receives an
ErrorMsgContent with a version of cmp1999 then it MUST abort the
current transaction. It MAY subsequently retry the transaction
using version cmp1999 messages.
If client receives a non-error PKIMessage with a version of cmp1999
then it MAY decide to continue the transaction (if the transaction
hasn't finished) using RFC 2510 semantics. If it does not choose to
do so and the transaction is not finished, then it MUST abort the
transaction and send an ErrorMsgContent with a version of cmp1999.
5.1.2 Servers receiving version cmp1999 PKIMessages
If a server receives a version cmp1999 message it MAY revert to RFC
2510 behaviour and respond with version cmp1999 messages. If it does
not choose to do so, then it MUST send back an ErrorMsgContent as
described above in Section 5.
Adams & Farrell Expires Oct. 2003 [Page 55]
SECURITY CONSIDERATIONS
This entire memo is about security mechanisms.
Some cryptographic considerations are worth explicitly spelling out. In
the protocols specified above, when an end entity is required to
prove possession of a decryption key, it is effectively challenged to
decrypt something (its own certificate). This scheme (and many
others!) could be vulnerable to an attack if the possessor of the
decryption key in question could be fooled into decrypting an
arbitrary challenge and returning the cleartext to an attacker.
Although in this specification a number of other failures in security
are required in order for this attack to succeed, it is conceivable
that some future services (e.g., notary, trusted time) could
potentially be vulnerable to such attacks. For this reason we re-
iterate the general rule that implementations should be very careful
about decrypting arbitrary "ciphertext" and revealing recovered
"plaintext" since such a practice can lead to serious security
vulnerabilities.
Note also that exposing a private key to the CA/RA as a proof-of-
possession technique can carry some security risks (depending upon
whether or not the CA/RA can be trusted to handle such material
appropriately). Implementers are advised to exercise caution in
selecting and using this particular POP mechanism.
A small subgroup attack during a Diffie-Hellman key exchange may be
carried out as follows. A malicious end entity may deliberately
choose D-H parameters that enable him/her to derive (a significant
number of bits of) the D-H private key of the CA during a key
archival or key recovery operation. Armed with this knowledge, the
EE would then be able to retrieve the decryption private key of
another unsuspecting end entity, EE2, during EE2's legitimate key
archival or key recovery operation with that CA. In order to avoid
the possibility of such an attack, two courses of action are
available. (1) The CA may generate a fresh D-H key pair to be used
as a protocol encryption key pair for each EE with which it
interacts. (2) The CA may enter into a key validation protocol (not
specified in this document) with each requesting end entity to ensure
that the EE's protocol encryption key pair will not facilitate this
attack. Option (1) is clearly simpler (requiring no extra protocol
exchanges from either party) and is therefore RECOMMENDED.
Adams & Farrell Expires Oct. 2003 [Page 56]
Normative References
[COR95] ISO/IEC JTC 1/SC 21, Technical Corrigendum 2 to ISO/IEC
9594-8: 1990 & 1993 (1995:E), July 1995.
[MvOV97] A. Menezes, P. van Oorschot, S. Vanstone, "Handbook of
Applied Cryptography", CRC Press, 1997.
[RFC2104] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC: Keyed
Hashing for Message Authentication", RFC 2104, February
1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2202] Cheng, P. and R. Glenn, "Test Cases for HMAC-MD5 and HMAC-
SHA-1", RFC 2202, September 1997.
[RFC2279] Yergeau, F., "UTF-8, A Transformation Format of ISO 10646",
RFC 2279, January 1998.
[RFC2482] Whistler, K., Adams, G., "Language Tagging in Unicode
Plain Text", RFC 2482, January 1999.
[rfc2511bis] Myers, M., Adams, C., Solo, D. and D. Kemp, "Certificate
Request Message Format", Internet Draft, work in progress
(see also Appendix D in this specification for some
behavioral clarifications to the rfc2511bis ASN.1 module
definition).
[RFC3066] Alvestrand, H., "Tags for the Identification of Languages",
RFC 3066, January, 2001.
[X509-AM] ISO/IEC JTC1/SC 21, Draft Amendments DAM 4 to ISO/IEC
9594-2, DAM 2 to ISO/IEC 9594-6, DAM 1 to ISO/IEC 9594-7,
and DAM 1 to ISO/IEC 9594-8 on Certificate Extensions, 1
December, 1996.
Informative References
[PKCS7] RSA Laboratories, "The Public-Key Cryptography Standards
(PKCS)", RSA Data Security Inc., Redwood City, California,
November 1993 Release.
[PKCS10] RSA Laboratories, "The Public-Key Cryptography Standards
(PKCS)", RSA Data Security Inc., Redwood City, California,
November 1993 Release. (See also Nystrom, M. and B. Kaliski,
"PKCS #10: Certification Request Syntax Specification,
Version 1.7", RFC 2986, November 2000.)
Adams & Farrell Expires Oct. 2003 [Page 57]
[PKCS11] RSA Laboratories, The Public-Key Cryptography Standards -
"PKCS #11 v2.10: Cryptographic Token Interface Standard",
RSA Security Inc., December 1999.
[RFC1766] Alvestrand, H., "Tags for the Identification of Languages",
RFC 1766, March 1995.
[RFC1847] Galvin, J., Murphy, S. Crocker, S. and N. Freed, "Security
Multiparts for MIME: Multipart/Signed and Multipart/
Encrypted", RFC 1847, October 1995.
[RFC2559] Boeyen, S., Howes, T., Richard, P., "Internet X.509
Public Key Infrastructure, Operational Protocols: LDAPv2",
RFC 2559, April 1999.
[RFC2585] Housley, R., Hoffman, P., "Internet X.509 Public Key
Infrastructure, Operational Protocols: FTP and HTTP",
RFC 2585, May 1999.
Acknowledgements
The authors gratefully acknowledge the contributions of various
members of the IETF PKIX Working Group and the ICSA CA-talk mailing
list (a list solely devoted to discussing CMP interoperability
efforts). Many of these contributions significantly clarified and
improved the utility of this specification.
Authors' Addresses
Carlisle Adams
Entrust, Inc.
1000 Innovation Drive,
Ottawa, Ontario
Canada K2K 3E7
EMail: cadams@entrust.com
Stephen Farrell
Baltimore Technologies
39 Parkgate Street
Dublin 8
IRELAND
EMail: stephen.farrell@baltimore.ie
Adams & Farrell Expires Oct. 2003 [Page 58]
APPENDIX A: Reasons for the presence of RAs
The reasons which justify the presence of an RA can be split into
those which are due to technical factors and those which are
organizational in nature. Technical reasons include the following.
-If hardware tokens are in use, then not all end entities will have
the equipment needed to initialize these; the RA equipment can
include the necessary functionality (this may also be a matter of
policy).
-Some end entities may not have the capability to publish
certificates; again, the RA may be suitably placed for this.
-The RA will be able to issue signed revocation requests on behalf
of end entities associated with it, whereas the end entity may not
be able to do this (if the key pair is completely lost).
Some of the organizational reasons which argue for the presence of an
RA are the following.
-It may be more cost effective to concentrate functionality in the
RA equipment than to supply functionality to all end entities
(especially if special token initialization equipment is to be
used).
-Establishing RAs within an organization can reduce the number of
CAs required, which is sometimes desirable.
-RAs may be better placed to identify people with their
"electronic" names, especially if the CA is physically remote from
the end entity.
-For many applications there will already be in place some
administrative structure so that candidates for the role of RA are
easy to find (which may not be true of the CA).
Adams & Farrell Expires Oct. 2003 [Page 59]
Appendix B. PKI Management Message Profiles (REQUIRED).
This appendix contains detailed profiles for those PKIMessages which
MUST be supported by conforming implementations (see Section 4).
Profiles for the PKIMessages used in the following PKI management
operations are provided:
- initial registration/certification
- basic authenticated scheme
- certificate request
- key update
B1. General Rules for interpretation of these profiles.
1. Where OPTIONAL or DEFAULT fields are not mentioned in individual
profiles, they SHOULD be absent from the relevant message (i.e., a
receiver can validly reject a message containing such fields as
being syntactically incorrect).
Mandatory fields are not mentioned if they have an obvious value
(e.g., in this version of the specification, pvno is always 2).
2. Where structures occur in more than one message, they are
separately profiled as appropriate.
3. The algorithmIdentifiers from PKIMessage structures are profiled
separately.
4. A "special" X.500 DN is called the "NULL-DN"; this means a DN
containing a zero-length SEQUENCE OF RelativeDistinguishedNames
(its DER encoding is then '3000'H).
5. Where a GeneralName is required for a field but no suitable
value is available (e.g., an end entity produces a request before
knowing its name) then the GeneralName is to be an X.500 NULL-DN
(i.e., the Name field of the CHOICE is to contain a NULL-DN).
This special value can be called a "NULL-GeneralName".
6. Where a profile omits to specify the value for a GeneralName
then the NULL-GeneralName value is to be present in the relevant
PKIMessage field. This occurs with the sender field of the
PKIHeader for some messages.
7. Where any ambiguity arises due to naming of fields, the profile
names these using a "dot" notation (e.g., "certTemplate.subject"
means the subject field within a field called certTemplate).
8. Where a "SEQUENCE OF types" is part of a message, a zero-based
array notation is used to describe fields within the SEQUENCE OF
(e.g., crm[0].certReq.certTemplate.subject refers to a
subfield of the first CertReqMsg contained in a request message).
9. All PKI message exchanges in Sections B4-B6 require a certConf
message to be sent by the initiating entity and a PKIConfirm to be
sent by the responding entity. The PKIConfirm is not included in
some of the profiles given since its body is NULL and its header
contents are clear from the context. Any authenticated means can
be used for the protectionAlg (e.g., password-based MAC, if shared
secret information is known, or signature).
Adams & Farrell Expires Oct. 2003 [Page 60]
B2. Algorithm Use Profile
The following table contains definitions of algorithm uses within PKI
management protocols. The columns in the table are:
Name: an identifier used for message profiles
Use: description of where and for what the algorithm is used
Mandatory: an AlgorithmIdentifier which MUST be supported by
conforming implementations
Others: alternatives to the mandatory AlgorithmIdentifier
Name Use Mandatory Others
MSG_SIG_ALG Protection of PKI DSA/SHA-1 RSA/MD5,
messages using signature ECDSA, ...
MSG_MAC_ALG protection of PKI PasswordBasedMac HMAC,
messages using MACing X9.9...
SYM_PENC_ALG symmetric encryption of 3-DES (3-key- RC5,
an end entity's private EDE, CBC mode) CAST-128...
key where symmetric
key is distributed
out-of-band
PROT_ENC_ALG asymmetric algorithm D-H RSA,
used for encryption of ECDH, ...
(symmetric keys for
encryption of) private
keys transported in
PKIMessages
PROT_SYM_ALG symmetric encryption 3-DES (3-key- RC5,
algorithm used for EDE, CBC mode) CAST-128...
encryption of private
key bits (a key of this
type is encrypted using
PROT_ENC_ALG)
Mandatory AlgorithmIdentifiers and Specifications:
DSA/SHA-1:
AlgId: {1 2 840 10040 4 3};
NIST, FIPS PUB 186: Digital Signature Standard, 1994;
Public Modulus size: 1024 bits.
PasswordBasedMac:
{1 2 840 113533 7 66 13}, with SHA-1 {1 3 14 3 2 26} as the owf
parameter and HMAC-SHA1 {1 3 6 1 5 5 8 1 2} as the mac parameter;
(this specification), along with
NIST, FIPS PUB 180-1: Secure Hash Standard, April 1995;
H. Krawczyk, M. Bellare, R. Canetti, "HMAC: Keyed-Hashing for Message
Authentication", Internet Request for Comments 2104, February 1997.
HMAC key size: 160 bits (i.e., "K" = "H" in Section 3.1.3, "Shared
secret information")
Adams & Farrell Expires Oct. 2003 [Page 61]
3-DES:
{1 2 840 113549 3 7};
(used in RSA's BSAFE and in S/MIME).
D-H:
AlgId: {1 2 840 10046 2 1};
ANSI X9.42;
Public Modulus Size: 1024 bits.
DomainParameters ::= SEQUENCE {
p INTEGER, -- odd prime, p=jq +1
g INTEGER, -- generator, g^q = 1 mod p
q INTEGER, -- prime factor of p-1
j INTEGER OPTIONAL, -- cofactor, j>=2
validationParms ValidationParms OPTIONAL
}
ValidationParms ::= SEQUENCE {
seed BIT STRING, -- seed for prime generation
pGenCounter INTEGER -- parameter verification
}
B3. Proof of Possession Profile
POP fields for use (in signature field of pop field of
ProofOfPossession structure) when proving possession of a private
signing key which corresponds to a public verification key for which
a certificate has been requested.
Field Value Comment
algorithmIdentifier MSG_SIG_ALG only signature protection is
allowed for this proof
signature present bits calculated using MSG_SIG_ALG
<<Proof of possession of a private decryption key which corresponds
to a public encryption key for which a certificate has been requested
does not use this profile; the CertHash field of the certConf message
is used instead.>>
Not every CA/RA will do Proof-of-Possession (of signing key,
decryption key, or key agreement key) in the PKIX-CMP in-band
certification request protocol (how POP is done MAY ultimately be a
policy issue which is made explicit for any given CA in its
publicized Policy OID and Certification Practice Statement).
However, this specification MANDATES that CA/RA entities MUST do POP
(by some means) as part of the certification process. All end
entities MUST be prepared to provide POP (i.e., these components of
the PKIX-CMP protocol MUST be supported).
Adams & Farrell Expires Oct. 2003 [Page 62]
B4. Initial Registration/Certification (Basic Authenticated Scheme)
An (uninitialized) end entity requests a (first) certificate from a
CA. When the CA responds with a message containing a certificate, the
end entity replies with a certificate confirmation. The CA sends a
PKIConfirm back, closing the transaction. All messages are
authenticated.
This scheme allows the end entity to request certification of a
locally-generated public key (typically a signature key). The end
entity MAY also choose to request the centralized generation and
certification of another key pair (typically an encryption key pair).
Certification may only be requested for one locally generated public
key (for more, use separate PKIMessages).
The end entity MUST support proof-of-possession of the private key
associated with the locally-generated public key.
Preconditions:
1. The end entity can authenticate the CA's signature based on
out-of-band means
2. The end entity and the CA share a symmetric MACing key
Message flow:
Step# End entity PKI
1 format ir
2 -> ir ->
3 handle ir
4 format ip
5 <- ip <-
6 handle ip
7 format certConf
8 -> certConf ->
9 handle certConf
10 format PKIConf
11 <- PKIConf <-
12 handle PKIConf
For this profile, we mandate that the end entity MUST include all
(i.e., one or two) CertReqMsg in a single PKIMessage and that the PKI
(CA) MUST produce a single response PKIMessage which contains the
complete response (i.e., including the OPTIONAL second key pair, if
it was requested and if centralized key generation is supported). For
simplicity, we also mandate that this message MUST be the final one
(i.e., no use of "waiting" status value).
The end entity has an out of band interaction with the CA/RA. This
transaction established the shared secret, the referenceNumber and
OPTIONALLY the distinguished name used for both sender and subject
name in the certificate template. It is RECOMMENDED that the shared
secret be at least 12 characters long.
Adams & Farrell Expires Oct. 2003 [Page 63]
ir:
Field Value
recipient CA name
-- the name of the CA who is being asked to produce a certificate
protectionAlg MSG_MAC_ALG
-- only MAC protection is allowed for this request, based on
-- initial authentication key
senderKID referenceNum
-- the reference number which the CA has previously issued to
-- the end entity (together with the MACing key)
transactionID present
-- implementation-specific value, meaningful to end entity.
-- [If already in use at the CA then a rejection message MUST be
-- produced by the CA]
senderNonce present
-- 128 (pseudo-)random bits
freeText any valid value
Adams & Farrell Expires Oct. 2003 [Page 64]
body ir (CertReqMessages)
only one or two CertReqMsg
are allowed
-- if more certificates are required requests MUST be packaged in
-- separate PKIMessages
CertReqMsg one or two present
-- see below for details, note: crm[0] means the first (which MUST
-- be present), crm[1] means the second (which is OPTIONAL, and used
-- to ask for a centrally-generated key)
crm[0].certReq. fixed value of zero
certReqId
-- this is the index of the template within the message
crm[0].certReq present
certTemplate
-- MUST include subject public key value, otherwise unconstrained
crm[0].pop... optionally present if public key
POPOSigningKey from crm[0].certReq.certTemplate is
a signing key
-- proof of possession MAY be required in this exchange (see Section
-- B3 for details)
crm[0].certReq. optionally present
controls.archiveOptions
-- the end entity MAY request that the locally-generated private key
-- be archived
crm[0].certReq. optionally present
controls.publicationInfo
-- the end entity MAY ask for publication of resulting cert.
crm[1].certReq fixed value of one
certReqId
-- the index of the template within the message
crm[1].certReq present
certTemplate
-- MUST NOT include actual public key bits, otherwise unconstrained
-- (e.g., the names need not be the same as in crm[0]). Note that
-- subjectPublicKeyInfo MAY be present and contain an
-- AlgorithmIdentifier followed by a zero-length BIT STRING for the
-- subjectPublicKey if it is desired to inform the CA/RA of algorithm
-- and parameter preferences regarding the to-be-generated key pair.
crm[1].certReq. present [object identifier MUST be PROT_ENC_ALG]
controls.protocolEncrKey
-- if centralized key generation is supported by this CA, this
-- short-term asymmetric encryption key (generated by the end entity)
-- will be used by the CA to encrypt (a symmetric key used to encrypt)
-- a private key generated by the CA on behalf of the end entity
crm[1].certReq. optionally present
controls.archiveOptions
crm[1].certReq. optionally present
controls.publicationInfo
protection present
-- bits calculated using MSG_MAC_ALG
Adams & Farrell Expires Oct. 2003 [Page 65]
ip:
Field Value
sender CA name
-- the name of the CA who produced the message
messageTime present
-- time at which CA produced message
protectionAlg MS_MAC_ALG
-- only MAC protection is allowed for this response
senderKID referenceNum
-- the reference number which the CA has previously issued to the
-- end entity (together with the MACing key)
transactionID present
-- value from corresponding ir message
senderNonce present
-- 128 (pseudo-)random bits
recipNonce present
-- value from senderNonce in corresponding ir message
freeText any valid value
body ip (CertRepMessage)
contains exactly one response
for each request
-- The PKI (CA) responds to either one or two requests as appropriate.
-- crc[0] denotes the first (always present); crc[1] denotes the
-- second (only present if the ir message contained two requests and
-- if the CA supports centralized key generation).
crc[0]. fixed value of zero
certReqId
-- MUST contain the response to the first request in the corresponding
-- ir message
crc[0].status. present, positive values allowed:
status "accepted", "grantedWithMods"
negative values allowed:
"rejection"
crc[0].status. present if and only if
failInfo crc[0].status.status is "rejection"
crc[0]. present if and only if
certifiedKeyPair crc[0].status.status is
"accepted" or "grantedWithMods"
certificate present unless end entity's public
key is an encryption key and POP
is done in this in-band exchange
encryptedCert present if and only if end entity's
public key is an encryption key and
POP done in this in-band exchange
publicationInfo optionally present
-- indicates where certificate has been published (present at
-- discretion of CA)
Adams & Farrell Expires Oct. 2003 [Page 66]
crc[1]. fixed value of one
certReqId
-- MUST contain the response to the second request in the
-- corresponding ir message
crc[1].status. present, positive values allowed:
status "accepted", "grantedWithMods"
negative values allowed:
"rejection"
crc[1].status. present if and only if
failInfo crc[0].status.status is "rejection"
crc[1]. present if and only if
certifiedKeyPair crc[0].status.status is "accepted"
or "grantedWithMods"
certificate present
privateKey present (see Appendix D)
publicationInfo optionally present
-- indicates where certificate has been published (present at
-- discretion of CA)
protection present
-- bits calculated using MSG_MAC_ALG
extraCerts optionally present
-- the CA MAY provide additional certificates to the end entity
certConf:
Field Value
sender present
-- same as in ir
recipient CA name
-- the name of the CA who was asked to produce a certificate
transactionID present
-- value from corresponding ir and ip messages
senderNonce present
-- 128 (pseudo-) random bits
recipNonce present
-- value from senderNonce in corresponding ip message
protectionAlg MSG_MAC_ALG
-- only MAC protection is allowed for this message. The MAC is
-- based on the initial auth'n key shared between the EE and the CA.
senderKID referenceNum
-- the reference number which the CA has previously issued to the
-- end entity (together with the MACing key)
body certConf
-- see Section 3.3.18 for the contents of the certConf fields
-- Note: two CertStatus structures are required if both an
-- encryption and a signing certificate were sent.
protection present
-- bits calculated using MSG_MAC_ALG
Adams & Farrell Expires Oct. 2003 [Page 67]
PKIConf:
Field Value
sender present
-- same as in ip
recipient present
-- sender name from certConf
transactionID present
-- value from certConf message
senderNonce present
-- 128 (pseudo-) random bits
recipNonce present
-- value from senderNonce from certConf message
protectionAlg MSG_MAC_ALG
-- only MAC protection is allowed for this message.
senderKID referenceNum
body PKIConf
protection present
-- bits calculated using MSG_MAC_ALG
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B5. Certificate Request
An (initialized) end entity requests a certificate from a CA (for any
reason). When the CA responds with a message containing a
certificate, the end entity replies with a certificate confirmation.
The CA replies with a PKIConfirm, to close the transaction. All
messages are authenticated.
The profile for this exchange is identical to that given in Section
B4 with the following exceptions:
- sender name SHOULD be present
- protectionAlg of MSG_SIG_ALG MUST be supported (MSG_MAC_ALG MAY
also be supported) in request, response, certConfirm and
PKIConfirm messages;
- senderKID and recipKID are only present if required for message
verification;
- body is cr or cp;
- body may contain one or two CertReqMsg structures, but either
CertReqMsg may be used to request certification of a locally-
generated public key or a centrally-generated public key (i.e.,
the position-dependence requirement of Section B4 is removed);
- protection bits are calculated according to the protectionAlg
field.
B6. Key Update Request
An (initialized) end entity requests a certificate from a CA (to
update the key pair and/or corresponding certificate that it already
possesses). When the CA responds with a message containing a
certificate, the end entity replies with a certificate confirmation.
The CA replies with a PKIConfirm, to close the transaction. All
messages are authenticated.
The profile for this exchange is identical to that given in Section
B4 with the following exceptions:
- sender name SHOULD be present
- protectionAlg of MSG_SIG_ALG MUST be supported (MSG_MAC_ALG MAY
also be supported) in request, response, certConfirm and
PKIConfirm messages;
- senderKID and recipKID are only present if required for message
verification;
- body is kur or kup;
- body may contain one or two CertReqMsg structures, but either
CertReqMsg may be used to request certification of a locally-
generated public key or a centrally-generated public key (i.e.,
the position-dependence requirement of Section B4 is removed);
- protection bits are calculated according to the protectionAlg
field;
- regCtrl OldCertId SHOULD be used (unless it is clear to both
sender and receiver - by means not specified in this document -
that it is not needed).
Adams & Farrell Expires Oct. 2003 [Page 69]
Appendix C. PKI Management Message Profiles (OPTIONAL).
This appendix contains detailed profiles for those PKIMessages which
MAY be supported by implementations (in addition to the messages which
MUST be supported - see Section 4 and Appendix B).
Profiles for the PKIMessages used in the following PKI management
operations are provided:
- root CA key update
- information request/response
- cross-certification request/response (1-way)
- in-band initialization using external identity certificate
<<Later versions of this document may extend the above to include
profiles for the operations listed below (along with other
operations, if desired).>>
- revocation request
- certificate publication
- CRL publication
C1. General Rules for interpretation of these profiles.
(Identical to Appendix B1.)
C2. Algorithm Use Profile
(Identical to Appendix B2.)
C3. "Self-signed" certificates
Profile of how a Certificate structure may be "self-signed". These
structures are used for distribution of "root" CA public keys. This
can occur in one of three ways (see Section 2.4 above for a
description of the use of these structures):
Type Function
newWithNew a true "self-signed" certificate; the contained public
key MUST be usable to verify the signature (though this
provides only integrity and no authentication whatsoever)
oldWithNew previous root CA public key signed with new private key
newWithOld new root CA public key signed with previous private key
Adams & Farrell Expires Oct. 2003 [Page 70]
<<Such certificates (including relevant extensions) must contain
"sensible" values for all fields. For example, when present
subjectAltName MUST be identical to issuerAltName, and when present
keyIdentifiers must contain appropriate values, et cetera.>>
C4. Root CA Key Update
A root CA updates its key pair. It then produces a CA key update
announcement message which can be made available (via some
transport mechanism) to the relevant end entities. A confirmation
message is NOT REQUIRED from the end entities.
ckuann message:
Field Value Comment
sender CA name CA name
body ckuann(CAKeyUpdAnnContent)
oldWithNew present see Section C3 above
newWithOld present see Section C3 above
newWithNew present see Section C3 above
extraCerts optionally present can be used to "publish"
certificates (e.g.,
certificates signed using
the new private key)
C5. PKI Information request/response
The end entity sends general message to the PKI requesting details
which will be required for later PKI management operations. RA/CA
responds with general response. If an RA generates the response then
it will simply forward the equivalent message which it previously
received from the CA, with the possible addition of certificates
to the extraCerts fields of the PKIMessage. A confirmation message is
NOT REQUIRED from the end entity.
Message Flows:
Step# End entity PKI
1 format genm
2 -> genm ->
3 handle genm
4 produce genp
5 <- genp <-
6 handle genp
Adams & Farrell Expires Oct. 2003 [Page 71]
genM:
Field Value
recipient CA name
-- the name of the CA as contained in issuerAltName extensions or
-- issuer fields within certificates
protectionAlg MSG_MAC_ALG or MSG_SIG_ALG
-- any authenticated protection alg.
SenderKID present if required
-- must be present if required for verification of message protection
freeText any valid value
body genr (GenReqContent)
GenMsgContent empty SEQUENCE
-- all relevant information requested
protection present
-- bits calculated using MSG_MAC_ALG or MSG_SIG_ALG
genP:
Field Value
sender CA name
-- name of the CA which produced the message
protectionAlg MSG_MAC_ALG or MSG_SIG_ALG
-- any authenticated protection alg.
senderKID present if required
-- must be present if required for verification of message protection
body genp (GenRepContent)
CAProtEncCert present (object identifier one
of PROT_ENC_ALG), with relevant
value
-- to be used if end entity needs to encrypt information for the CA
-- (e.g., private key for recovery purposes)
SignKeyPairTypes present, with relevant value
-- the set of signature algorithm identifiers which this CA will
-- certify for subject public keys
EncKeyPairTypes present, with relevant value
-- the set of encryption/key agreement algorithm identifiers which
-- this CA will certify for subject public keys
PreferredSymmAlg present (object identifier one
of PROT_SYM_ALG) , with relevant
value
-- the symmetric algorithm which this CA expects to be used in later
-- PKI messages (for encryption)
CAKeyUpdateInfo optionally present, with
relevant value
-- the CA MAY provide information about a relevant root CA key pair
-- using this field (note that this does not imply that the responding
-- CA is the root CA in question)
Adams & Farrell Expires Oct. 2003 [Page 72]
CurrentCRL optionally present, with relevant value
-- the CA MAY provide a copy of a complete CRL (i.e., fullest possible
-- one)
protection present
-- bits calculated using MSG_MAC_ALG or MSG_SIG_ALG
extraCerts optionally present
-- can be used to send some certificates to the end entity. An RA MAY
-- add its certificate here.
C6. Cross certification request/response (1-way)
Creation of a single cross-certificate (i.e., not two at once). The
requesting CA MAY choose who is responsible for publication of the
cross-certificate created by the responding CA through use of the
PKIPublicationInfo control.
Preconditions:
1. Responding CA can verify the origin of the request (possibly
requiring out-of-band means) before processing the request.
2. Requesting CA can authenticate the authenticity of the origin of
the response (possibly requiring out-of-band means) before
processing the response
The use of certificate confirmation and the corresponding server
confirmation is determined by the generalInfo field in the PKIHeader
(see Section 3.1.1). The following profile does not mandate support
for either confirmation.
Message Flows:
Step# Requesting CA Responding CA
1 format ccr
2 -> ccr ->
3 handle ccr
4 produce ccp
5 <- ccp <-
6 handle ccp
Adams & Farrell Expires Oct. 2003 [Page 73]
ccr:
Field Value
sender Requesting CA name
-- the name of the CA who produced the message
recipient Responding CA name
-- the name of the CA who is being asked to produce a certificate
messageTime time of production of message
-- current time at requesting CA
protectionAlg MSG_SIG_ALG
-- only signature protection is allowed for this request
senderKID present if required
-- must be present if required for verification of message protection
recipKID present if required
-- must be present if required for verification of message protection
transactionID present
-- implementation-specific value, meaningful to requesting CA.
-- [If already in use at responding CA then a rejection message
-- MUST be produced by responding CA]
senderNonce present
-- 128 (pseudo-)random bits
freeText any valid value
body ccr (CertReqMessages)
only one CertReqMsg
allowed
-- if multiple cross certificates are required they MUST be packaged
-- in separate PKIMessages
certTemplate present
-- details follow
version v1 or v3
-- <<v3 STRONGLY RECOMMENDED>>
signingAlg present
-- the requesting CA must know in advance with which algorithm it
-- wishes the certificate to be signed
subject present
-- may be NULL-DN only if subjectAltNames extension value proposed
validity present
-- MUST be completely specified (i.e., both fields present)
issuer present
-- may be NULL-DN only if issuerAltNames extension value proposed
publicKey present
-- the key to be certified (which must be for a signing algorithm)
extensions optionally present
-- a requesting CA must propose values for all extensions which it
-- requires to be in the cross-certificate
POPOSigningKey present
-- see "Proof of possession profile" (Section B3)
protection present
-- bits calculated using MSG_SIG_ALG
extraCerts optionally present
-- MAY contain any additional certificates that requester wishes
-- to include
Adams & Farrell Expires Oct. 2003 [Page 74]
ccp:
Field Value
sender Responding CA name
-- the name of the CA who produced the message
recipient Requesting CA name
-- the name of the CA who asked for production of a certificate
messageTime time of production of message
-- current time at responding CA
protectionAlg MSG_SIG_ALG
-- only signature protection is allowed for this message
senderKID present if required
-- must be present if required for verification of message
-- protection
recipKID present if required
transactionID present
-- value from corresponding ccr message
senderNonce present
-- 128 (pseudo-)random bits
recipNonce present
-- senderNonce from corresponding ccr message
freeText any valid value
body ccp (CertRepMessage)
only one CertResponse allowed
-- if multiple cross certificates are required they MUST be packaged
-- in separate PKIMessages
response present
status present
PKIStatusInfo.status present
-- if PKIStatusInfo.status is one of:
-- accepted, or
-- grantedWithMods,
-- then certifiedKeyPair MUST be present and failInfo MUST be absent
failInfo present depending on
PKIStatusInfo.status
-- if PKIStatusInfo.status is:
-- rejection
-- then certifiedKeyPair MUST be absent and failInfo MUST be present
-- and contain appropriate bit settings
certifiedKeyPair present depending on
PKIStatusInfo.status
certificate present depending on
certifiedKeyPair
-- content of actual certificate must be examined by requesting CA
-- before publication
protection present
-- bits calculated using MSG_SIG_ALG
extraCerts optionally present
-- MAY contain any additional certificates that responder wishes
-- to include
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C7. In-band initialization using external identity certificate
An (uninitialized) end entity wishes to initialize into the PKI with
a CA, CA-1. It uses, for authentication purposes, a pre-existing
identity certificate issued by another (external) CA, CA-X. A trust
relationship must already have been established between CA-1 and CA-X
so that CA-1 can validate the EE identity certificate signed by CA-X.
Furthermore, some mechanism must already have been established within
the Personal Security Environment (PSE) of the EE that would allow it
to authenticate and verify PKIMessages signed by CA-1 (as one example,
the PSE may contain a certificate issued for the public key of CA-1,
signed by another CA that the EE trusts on the basis of out-of-band
authentication techniques).
The EE sends an initialization request to start the transaction.
When CA-1 responds with a message containing the new certificate, the
end entity replies with a certificate confirmation. CA-1 replies with
a PKIConfirm to close the transaction. All messages are signed (the EE
messages are signed using the private key corresponding to the public
key in its external identity certificate; the CA-1 messages are signed
using the private key corresponding to the public key in a certificate
that can be chained to a trust anchor in the EE's PSE).
The profile for this exchange is identical to that given in Section
B4 with the following exceptions:
- the EE and CA-1 do not share a symmetric MACing key (i.e., there is
no out-of-band shared secret information between these entities);
- sender name in ir MUST be present (and identical to the subject
name present in the external identity certificate);
- protectionAlg of MSG_SIG_ALG MUST be used in all messages;
- external identity cert. MUST be carried in ir extraCerts field
- senderKID and recipKID are not used;
- body is ir or ip;
- protection bits are calculated according to the protectionAlg
field.
Adams & Farrell Expires Oct. 2003 [Page 76]
Appendix D: Request Message Behavioral Clarifications
The following definitions are from rfc2511bis. They are included here
in order to codify behavioral clarifications to that request
message; otherwise, all syntax and semantics are identical to rfc2511bis.
CertRequest ::= SEQUENCE {
certReqId INTEGER,
certTemplate CertTemplate,
controls Controls OPTIONAL }
-- If certTemplate is an empty SEQUENCE (i.e., all fields omitted), then
-- controls MAY contain the id-regCtrl-altCertTemplate control, specifying
-- a template for a certificate other than an X.509v3 public-key
-- certificate. Conversely, if certTemplate is not empty (i.e., at least
-- one field is present), then controls MUST NOT contain id-regCtrl-
-- altCertTemplate. The new control is defined as follows:
id-regCtrl-altCertTemplate OBJECT IDENTIFIER ::= {id-regCtrl 7}
AltCertTemplate ::= AttributeTypeAndValue
POPOSigningKey ::= SEQUENCE {
poposkInput [0] POPOSigningKeyInput OPTIONAL,
algorithmIdentifier AlgorithmIdentifier,
signature BIT STRING }
-- **********
-- * For the purposes of this specification, the ASN.1 comment given
-- * in rfc2511bis pertains not only to certTemplate, but also to
-- * the altCertTemplate control. That is,
-- **********
-- * The signature (using "algorithmIdentifier") is on the DER-encoded
-- * value of poposkInput (i.e., the "value" OCTETs of the
-- * POPOSigningKeyInput DER). NOTE: If CertReqMsg certReq certTemplate
-- * (or the altCertTemplate control) contains the subject and publicKey
-- * values, then poposkInput MUST be omitted and the signature MUST be
-- * computed on the DER-encoded value of CertReqMsg certReq (or the DER-
-- * encoded value of AltCertTemplate). If certTemplate/altCertTemplate
-- * does not contain both the subject and public key values (i.e., if
-- * it contains only one of these, or neither), then poposkInput MUST
-- * be present and MUST be signed.
-- **********
POPOPrivKey ::= CHOICE {
thisMessage [0] BIT STRING,
-- **********
-- * the type of "thisMessage" is given as BIT STRING in
-- * rfc2511bis; it should be "EncryptedValue" (in accordance with
-- * Section 3.2.2 of this specification). Therefore, this document makes
-- * the behavioral clarification of specifying that the contents of
-- * "thisMessage" MUST be encoded as an EncryptedValue and then wrapped
-- * in a BIT STRING. This allows the necessary conveyance and protection
-- * of the private key while maintaining bits-on-the-wire compatibility
-- * with rfc2511bis.
-- **********
subsequentMessage [1] SubsequentMessage,
dhMAC [2] BIT STRING }
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Appendix E: The Use of "Revocation Passphrase"
A revocation request must incorporate suitable security mechanisms,
including proper authentication, in order to reduce the probability of
successful denial-of-service attacks. A digital signature on the request
- MANDATORY to support within this specification if revocation requests
are supported - can provide the authentication required, but there are
circumstances under which an alternative mechanism may be desirable (e.g.,
when the private key is no longer accessible and the entity wishes to
request a revocation prior to re-certification of another key pair). In
order to accommodate such circumstances, a PasswordBasedMAC on the
request is also MANDATORY to support within this specification (subject
to local security policy for a given environment) if revocation requests
are supported and if shared secret information can be established
between the requester and the responder prior to the need for revocation.
A mechanism that has seen use in some environments is "revocation
passphrase", in which a value of sufficient entropy (i.e., a relatively
long passphrase rather than a short password) is shared between (only)
the entity and the CA/RA at some point prior to revocation, and this
value is later used to authenticate the revocation request.
In this specification, the following technique to establish shared secret
information (i.e., a revocation passphrase) is OPTIONAL to support. Its
precise use in CMP messages is as follows.
- The OID and value specified in Section 3.3.19.9 MAY be sent in a
GenMsg message at any time, or MAY be sent in the generalInfo field
of the PKIHeader of any PKIMessage at any time. (In particular, the
EncryptedValue may be sent in the header of the certConf message that
confirms acceptance of certificates requested in an initialization
request or certificate request message.) This conveys a revocation
passphrase chosen by the entity (i.e., the decrypted bytes of the
encValue field) to the relevant CA/RA; furthermore, the transfer is
accomplished with appropriate confidentiality characteristics (since
the passphrase is encrypted under the CA/RA's protocolEncryptionKey).
- If a CA/RA receives the revocation passphrase (OID and value specified
in Section 3.3.19.9) in a GenMsg, it MUST construct and send a GenRep
message which includes the OID (with absent value) specified in
Section 3.3.19.9. If the CA/RA receives the revocation passphrase
in the generalInfo field of a PKIHeader of any PKIMessage, it MUST
include the OID (with absent value) in the generalInfo field of the
PKIHeader of the corresponding response PKIMessage. If the CA/RA is
unable to return the appropriate response message for any
reason, it MUST send an error message with a status of "rejection"
and, optionally, a failInfo reason set.
- The valueHint field of EncryptedValue MAY contain a key identifier
(chosen by the entity, along with the passphrase itself) to assist
in later retrieval of the correct passphrase (e.g., when the
revocation request is constructed by the entity and received by the
CA/RA).
Adams & Farrell Expires Oct. 2003 [Page 78]
- The revocation request message is protected by a PasswordBasedMAC,
with the revocation passphrase as the key. If appropriate, the
senderKID field in the PKIHeader MAY contain the value previously
transmitted in valueHint.
Using the technique specified above, the revocation passphrase may be
initially established and updated at any time without requiring extra
messages or out-of-band exchanges. For example, the revocation request
message itself (protected and authenticated through a MAC that uses the
revocation passphrase as a key) may contain in the PKIHeader a new
revocation passphrase to be used for authenticating future revocation
requests for any of the entity's other certificates. In some
environments this may be preferable to mechanisms that reveal the
passphrase in the revocation request message, since this can allow a
denial-of-service attack in which the revealed passphrase is used by
an unauthorized third party to authenticate revocation requests on the
entity's other certificates. However, because the passphrase is not
revealed in the request message, there is no requirement that the
passphrase must always be updated when a revocation request is made
(that is, the same passphrase MAY be used by an entity to authenticate
revocation requests for different certificates at different times).
Furthermore, the above technique can provide strong cryptographic
protection over the entire revocation request message even when a
digital signature is not used. Techniques that do authentication of
the revocation request by simply revealing the revocation passphrase
typically do not provide cryptographic protection over the fields of
the request message (so that a request for revocation of one certificate
may be modified by an unauthorized third party to a request for
revocation of another certificate for that entity).
Adams & Farrell Expires Oct. 2003 [Page 79]
Appendix F: "Compilable" ASN.1 Module using 1988 Syntax
PKIXCMP {iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0) id-mod-cmp2000(16)}
DEFINITIONS EXPLICIT TAGS ::=
BEGIN
-- EXPORTS ALL --
IMPORTS
Certificate, CertificateList, Extensions, AlgorithmIdentifier,
UTF8String -- if required; otherwise, comment out
FROM PKIX1Explicit88 {iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7)
id-mod(0) id-pkix1-explicit-88(1)}
GeneralName, KeyIdentifier
FROM PKIX1Implicit88 {iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7)
id-mod(0) id-pkix1-implicit-88(2)}
CertTemplate, PKIPublicationInfo, EncryptedValue, CertId,
CertReqMessages
FROM PKIXCRMF {iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7)
id-mod(0) id-mod-crmf(5)}
-- see also the behavioral clarifications to CRMF codified in
-- Appendix D of this specification
CertificationRequest
FROM PKCS-10 {iso(1) member-body(2) us(840) rsadsi(113549)
pkcs(1) pkcs-10(10) modules(1) pkcs-10(1)}
-- (specified in RFC 2986 with 1993 ASN.1 syntax and IMPLICIT
-- tags). Alternatively, implementers may directly include
-- the [PKCS10] syntax in this module
;
Adams & Farrell Expires Oct. 2003 [Page 80]
-- the rest of the module contains locally-defined OIDs and constructs --
CMPCertificate ::= CHOICE {
x509v3PKCert Certificate
}
-- This syntax, while bits-on-the-wire compatible with the standard
-- X.509 definition of "Certificate", allows the possibility of future
-- certificate types (such as X.509 attribute certificates, WAP WTLS
-- certificates, or other kinds of certificates) within this
-- certificate management protocol, should a need ever arise to support
-- such generality. Those implementations that do not foresee a need to
-- ever support other certificate types MAY, if they wish, comment out
-- the above structure and "un-comment" the following one prior to
-- compiling this ASN.1 module. (Note that interoperability with
-- implementations that don't do this will be unaffected by this change.)
-- CMPCertificate ::= Certificate
PKIMessage ::= SEQUENCE {
header PKIHeader,
body PKIBody,
protection [0] PKIProtection OPTIONAL,
extraCerts [1] SEQUENCE SIZE (1..MAX) OF CMPCertificate OPTIONAL
}
PKIMessages ::= SEQUENCE SIZE (1..MAX) OF PKIMessage
PKIHeader ::= SEQUENCE {
pvno INTEGER { cmp1999(1), cmp2000(2) },
sender GeneralName,
-- identifies the sender
recipient GeneralName,
-- identifies the intended recipient
Adams & Farrell Expires Oct. 2003 [Page 81]
messageTime [0] GeneralizedTime OPTIONAL,
-- time of production of this message (used when sender
-- believes that the transport will be "suitable"; i.e.,
-- that the time will still be meaningful upon receipt)
protectionAlg [1] AlgorithmIdentifier OPTIONAL,
-- algorithm used for calculation of protection bits
senderKID [2] KeyIdentifier OPTIONAL,
recipKID [3] KeyIdentifier OPTIONAL,
-- to identify specific keys used for protection
transactionID [4] OCTET STRING OPTIONAL,
-- identifies the transaction; i.e., this will be the same in
-- corresponding request, response, certConf, and PKIConf messages
senderNonce [5] OCTET STRING OPTIONAL,
recipNonce [6] OCTET STRING OPTIONAL,
-- nonces used to provide replay protection, senderNonce
-- is inserted by the creator of this message; recipNonce
-- is a nonce previously inserted in a related message by
-- the intended recipient of this message
freeText [7] PKIFreeText OPTIONAL,
-- this may be used to indicate context-specific instructions
-- (this field is intended for human consumption)
generalInfo [8] SEQUENCE SIZE (1..MAX) OF
InfoTypeAndValue OPTIONAL
-- this may be used to convey context-specific information
-- (this field not primarily intended for human consumption)
}
PKIFreeText ::= SEQUENCE SIZE (1..MAX) OF UTF8String
-- text encoded as UTF-8 String [RFC2279] (note: each UTF8String
-- MAY include an RFC 1766/RFC 3066 language tag to indicate the
-- language of the contained text - see [RFC2482] for details)
PKIBody ::= CHOICE { -- message-specific body elements
ir [0] CertReqMessages, --Initialization Request
ip [1] CertRepMessage, --Initialization Response
cr [2] CertReqMessages, --Certification Request
cp [3] CertRepMessage, --Certification Response
p10cr [4] CertificationRequest, --imported from [PKCS10]
popdecc [5] POPODecKeyChallContent, --pop Challenge
popdecr [6] POPODecKeyRespContent, --pop Response
kur [7] CertReqMessages, --Key Update Request
kup [8] CertRepMessage, --Key Update Response
krr [9] CertReqMessages, --Key Recovery Request
krp [10] KeyRecRepContent, --Key Recovery Response
rr [11] RevReqContent, --Revocation Request
rp [12] RevRepContent, --Revocation Response
Adams & Farrell Expires Oct. 2003 [Page 82]
ccr [13] CertReqMessages, --Cross-Cert. Request
ccp [14] CertRepMessage, --Cross-Cert. Response
ckuann [15] CAKeyUpdAnnContent, --CA Key Update Ann.
cann [16] CertAnnContent, --Certificate Ann.
rann [17] RevAnnContent, --Revocation Ann.
crlann [18] CRLAnnContent, --CRL Announcement
pkiconf [19] PKIConfirmContent, --Confirmation
nested [20] NestedMessageContent, --Nested Message
genm [21] GenMsgContent, --General Message
genp [22] GenRepContent, --General Response
error [23] ErrorMsgContent, --Error Message
certConf [24] CertConfirmContent, --Certificate confirm
pollReq [25] PollReqContent, --Polling request
pollRep [26] PollRepContent --Polling response
}
PKIProtection ::= BIT STRING
ProtectedPart ::= SEQUENCE {
header PKIHeader,
body PKIBody
}
id-PasswordBasedMac OBJECT IDENTIFIER ::= {1 2 840 113533 7 66 13}
PBMParameter ::= SEQUENCE {
salt OCTET STRING,
-- note: implementations MAY wish to limit acceptable sizes
-- of this string to values appropriate for their environment
-- in order to reduce the risk of denial-of-service attacks
owf AlgorithmIdentifier,
-- AlgId for a One-Way Function (SHA-1 recommended)
iterationCount INTEGER,
-- number of times the OWF is applied
-- note: implementations MAY wish to limit acceptable sizes
-- of this integer to values appropriate for their environment
-- in order to reduce the risk of denial-of-service attacks
mac AlgorithmIdentifier
-- the MAC AlgId (e.g., DES-MAC, Triple-DES-MAC [PKCS11],
} -- or HMAC [RFC2104, RFC2202])
id-DHBasedMac OBJECT IDENTIFIER ::= {1 2 840 113533 7 66 30}
DHBMParameter ::= SEQUENCE {
owf AlgorithmIdentifier,
-- AlgId for a One-Way Function (SHA-1 recommended)
mac AlgorithmIdentifier
-- the MAC AlgId (e.g., DES-MAC, Triple-DES-MAC [PKCS11],
} -- or HMAC [RFC2104, RFC2202])
NestedMessageContent ::= PKIMessages
PKIStatus ::= INTEGER {
accepted (0),
-- you got exactly what you asked for
grantedWithMods (1),
Adams & Farrell Expires Oct. 2003 [Page 83]
-- you got something like what you asked for; the
-- requester is responsible for ascertaining the differences
rejection (2),
-- you don't get it, more information elsewhere in the message
waiting (3),
-- the request body part has not yet been processed; expect to hear
-- more later (note: proper handling of this status response MAY
-- use the polling req/rep PKIMessages specified in Section 3.3.22;
-- alternatively, polling in the underlying transport layer MAY
-- have some utility in this regard)
revocationWarning (4),
-- this message contains a warning that a revocation is
-- imminent
revocationNotification (5),
-- notification that a revocation has occurred
keyUpdateWarning (6)
-- update already done for the oldCertId specified in
-- CertReqMsg
}
PKIFailureInfo ::= BIT STRING {
-- since we can fail in more than one way!
-- More codes may be added in the future if/when required.
badAlg (0),
-- unrecognized or unsupported Algorithm Identifier
badMessageCheck (1),
-- integrity check failed (e.g., signature did not verify)
badRequest (2),
-- transaction not permitted or supported
badTime (3),
-- messageTime was not sufficiently close to the system time,
-- as defined by local policy
badCertId (4),
-- no certificate could be found matching the provided criteria
badDataFormat (5),
-- the data submitted has the wrong format
wrongAuthority (6),
-- the authority indicated in the request is different from the
-- one creating the response token
incorrectData (7),
-- the requester's data is incorrect (for notary services)
missingTimeStamp (8),
-- when the timestamp is missing but should be there (by policy)
badPOP (9),
-- the proof-of-possession failed
certRevoked (10),
-- the certificate has already been revoked
certConfirmed (11),
-- the certificate has already been confirmed
wrongIntegrity (12),
-- invalid integrity, password based instead of signature or
-- vice versa
badRecipientNonce (13),
-- invalid recipient nonce, either missing or wrong value
Adams & Farrell Expires Oct. 2003 [Page 84]
timeNotAvailable (14),
-- the TSA's time source is not available
unacceptedPolicy (15),
-- the requested TSA policy is not supported by the TSA.
unacceptedExtension (16),
-- the requested extension is not supported by the TSA.
addInfoNotAvailable (17),
-- the additional information requested could not be understood
-- or is not available
badSenderNonce (18),
-- invalid sender nonce, either missing or wrong size
badCertTemplate (19),
-- invalid cert. template or missing mandatory information
signerNotTrusted (20),
-- signer of the message unknown or not trusted
transactionIdInUse (21),
-- the transaction identifier is already in use
unsupportedVersion (22),
-- the version of the message is not supported
notAuthorized (23),
-- the sender was not authorized to make the preceding request
-- or perform the preceding action
systemUnavail (24),
-- the request cannot be handled due to system unavailability
systemFailure (25),
-- the request cannot be handled due to system failure
duplicateCertReq (26)
-- certificate cannot be issued because a duplicate certificate
-- already exists
}
PKIStatusInfo ::= SEQUENCE {
status PKIStatus,
statusString PKIFreeText OPTIONAL,
failInfo PKIFailureInfo OPTIONAL
}
Adams & Farrell Expires Oct. 2003 [Page 85]
OOBCert ::= CMPCertificate
OOBCertHash ::= SEQUENCE {
hashAlg [0] AlgorithmIdentifier OPTIONAL,
certId [1] CertId OPTIONAL,
hashVal BIT STRING
-- hashVal is calculated over the DER encoding of the
-- self-signed certificate with the identifier certID.
}
POPODecKeyChallContent ::= SEQUENCE OF Challenge
-- One Challenge per encryption key certification request (in the
-- same order as these requests appear in CertReqMessages).
Challenge ::= SEQUENCE {
owf AlgorithmIdentifier OPTIONAL,
-- MUST be present in the first Challenge; MAY be omitted in any
-- subsequent Challenge in POPODecKeyChallContent (if omitted,
-- then the owf used in the immediately preceding Challenge is
-- to be used).
witness OCTET STRING,
-- the result of applying the one-way function (owf) to a
-- randomly-generated INTEGER, A. [Note that a different
-- INTEGER MUST be used for each Challenge.]
challenge OCTET STRING
-- the encryption (under the public key for which the cert.
-- request is being made) of Rand, where Rand is specified as
-- Rand ::= SEQUENCE {
-- int INTEGER,
-- - the randomly-generated INTEGER A (above)
-- sender GeneralName
-- - the sender's name (as included in PKIHeader)
-- }
}
POPODecKeyRespContent ::= SEQUENCE OF INTEGER
-- One INTEGER per encryption key certification request (in the
-- same order as these requests appear in CertReqMessages). The
-- retrieved INTEGER A (above) is returned to the sender of the
-- corresponding Challenge.
CertRepMessage ::= SEQUENCE {
caPubs [1] SEQUENCE SIZE (1..MAX) OF CMPCertificate OPTIONAL,
response SEQUENCE OF CertResponse
}
Adams & Farrell Expires Oct. 2003 [Page 86]
CertResponse ::= SEQUENCE {
certReqId INTEGER,
-- to match this response with corresponding request (a value
-- of -1 is to be used if certReqId is not specified in the
-- corresponding request)
status PKIStatusInfo,
certifiedKeyPair CertifiedKeyPair OPTIONAL,
rspInfo OCTET STRING OPTIONAL
-- analogous to the id-regInfo-utf8Pairs string defined
-- for regInfo in CertReqMsg [rfc2511bis]
}
CertifiedKeyPair ::= SEQUENCE {
certOrEncCert CertOrEncCert,
privateKey [0] EncryptedValue OPTIONAL,
-- see [rfc2511bis] for comment on encoding
publicationInfo [1] PKIPublicationInfo OPTIONAL
}
CertOrEncCert ::= CHOICE {
certificate [0] CMPCertificate,
encryptedCert [1] EncryptedValue
}
KeyRecRepContent ::= SEQUENCE {
status PKIStatusInfo,
newSigCert [0] CMPCertificate OPTIONAL,
caCerts [1] SEQUENCE SIZE (1..MAX) OF
CMPCertificate OPTIONAL,
keyPairHist [2] SEQUENCE SIZE (1..MAX) OF
CertifiedKeyPair OPTIONAL
}
RevReqContent ::= SEQUENCE OF RevDetails
RevDetails ::= SEQUENCE {
certDetails CertTemplate,
-- allows requester to specify as much as they can about
-- the cert. for which revocation is requested
-- (e.g., for cases in which serialNumber is not available)
crlEntryDetails Extensions OPTIONAL
-- requested crlEntryExtensions
}
RevRepContent ::= SEQUENCE {
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status SEQUENCE SIZE (1..MAX) OF PKIStatusInfo,
-- in same order as was sent in RevReqContent
revCerts [0] SEQUENCE SIZE (1..MAX) OF CertId OPTIONAL,
-- IDs for which revocation was requested (same order as status)
crls [1] SEQUENCE SIZE (1..MAX) OF CertificateList OPTIONAL
-- the resulting CRLs (there may be more than one)
}
CAKeyUpdAnnContent ::= SEQUENCE {
oldWithNew CMPCertificate, -- old pub signed with new priv
newWithOld CMPCertificate, -- new pub signed with old priv
newWithNew CMPCertificate -- new pub signed with new priv
}
CertAnnContent ::= CMPCertificate
RevAnnContent ::= SEQUENCE {
status PKIStatus,
certId CertId,
willBeRevokedAt GeneralizedTime,
badSinceDate GeneralizedTime,
crlDetails Extensions OPTIONAL
-- extra CRL details(e.g., crl number, reason, location, etc.)
}
CRLAnnContent ::= SEQUENCE OF CertificateList
CertConfirmContent ::= SEQUENCE OF CertStatus
CertStatus ::= SEQUENCE {
certHash OCTET STRING,
-- the hash of the certificate, using the same hash algorithm
-- as is used to create and verify the certificate signature
certReqId INTEGER,
-- to match this confirmation with the corresponding req/rep
statusInfo PKIStatusInfo OPTIONAL
}
PKIConfirmContent ::= NULL
Adams & Farrell Expires Oct. 2003 [Page 88]
InfoTypeAndValue ::= SEQUENCE {
infoType OBJECT IDENTIFIER,
infoValue ANY DEFINED BY infoType OPTIONAL
}
-- Example InfoTypeAndValue contents include, but are not limited to,
-- the following (un-comment in this ASN.1 module and use as
-- appropriate for a given environment):
--
-- id-it-caProtEncCert OBJECT IDENTIFIER ::= {id-it 1}
-- CAProtEncCertValue ::= CMPCertificate
-- id-it-signKeyPairTypes OBJECT IDENTIFIER ::= {id-it 2}
-- SignKeyPairTypesValue ::= SEQUENCE OF AlgorithmIdentifier
-- id-it-encKeyPairTypes OBJECT IDENTIFIER ::= {id-it 3}
-- EncKeyPairTypesValue ::= SEQUENCE OF AlgorithmIdentifier
-- id-it-preferredSymmAlg OBJECT IDENTIFIER ::= {id-it 4}
-- PreferredSymmAlgValue ::= AlgorithmIdentifier
-- id-it-caKeyUpdateInfo OBJECT IDENTIFIER ::= {id-it 5}
-- CAKeyUpdateInfoValue ::= CAKeyUpdAnnContent
-- id-it-currentCRL OBJECT IDENTIFIER ::= {id-it 6}
-- CurrentCRLValue ::= CertificateList
-- id-it-unsupportedOIDs OBJECT IDENTIFIER ::= {id-it 7}
-- UnsupportedOIDsValue ::= SEQUENCE OF OBJECT IDENTIFIER
-- id-it-keyPairParamReq OBJECT IDENTIFIER ::= {id-it 10}
-- KeyPairParamReqValue ::= OBJECT IDENTIFIER
-- id-it-keyPairParamRep OBJECT IDENTIFIER ::= {id-it 11}
-- KeyPairParamRepValue ::= AlgorithmIdentifer
-- id-it-revPassphrase OBJECT IDENTIFIER ::= {id-it 12}
-- RevPassphraseValue ::= EncryptedValue
-- id-it-implicitConfirm OBJECT IDENTIFIER ::= {id-it 13}
-- ImplicitConfirmValue ::= NULL
-- id-it-confirmWaitTime OBJECT IDENTIFIER ::= {id-it 14}
-- ConfirmWaitTimeValue ::= GeneralizedTime
-- id-it-origPKIMessage OBJECT IDENTIFIER ::= {id-it 15}
-- OrigPKIMessageValue ::= PKIMessages
-- id-it-suppLangTags OBJECT IDENTIFIER ::= {id-it 16}
-- SuppLangTagsValue ::= SEQUENCE OF UTF8String
--
-- where
--
-- id-pkix OBJECT IDENTIFIER ::= {iso(1) identified-organization(3)
-- dod(6) internet(1) security(5) mechanisms(5) pkix(7)}
-- and
-- id-it OBJECT IDENTIFIER ::= {id-pkix 4}
--
--
-- This construct MAY also be used to define new PKIX Certificate
-- Management Protocol request and response messages, or general-
-- purpose (e.g., announcement) messages for future needs or for
-- specific environments.
Adams & Farrell Expires Oct. 2003 [Page 89]
GenMsgContent ::= SEQUENCE OF InfoTypeAndValue
-- May be sent by EE, RA, or CA (depending on message content).
-- The OPTIONAL infoValue parameter of InfoTypeAndValue will typically
-- be omitted for some of the examples given above. The receiver is
-- free to ignore any contained OBJ. IDs that it does not recognize.
-- If sent from EE to CA, the empty set indicates that the CA may send
-- any/all information that it wishes.
GenRepContent ::= SEQUENCE OF InfoTypeAndValue
-- Receiver MAY ignore any contained OIDs that it does not recognize.
ErrorMsgContent ::= SEQUENCE {
pKIStatusInfo PKIStatusInfo,
errorCode INTEGER OPTIONAL,
-- implementation-specific error codes
errorDetails PKIFreeText OPTIONAL
-- implementation-specific error details
}
PollReqContent ::= SEQUENCE OF SEQUENCE {
certReqId INTEGER
}
PollRepContent ::= SEQUENCE OF SEQUENCE {
certReqId INTEGER,
checkAfter INTEGER, -- time in seconds
reason PKIFreeText OPTIONAL
}
END -- of CMP module
Adams & Farrell Expires Oct. 2003 [Page 90]
Appendix G: Registration of MIME Type for E-Mail or HTTP use
To: ietf-types@iana.org
Subject: Registration of MIME media type application/pkixcmp
MIME media type name: application
MIME subtype name: pkixcmp
Required parameters: -
Optional parameters: -
Encoding considerations:
Content may contain arbitrary octet values (the ASN.1 DER encoding of
a PKI message, as defined in the IETF PKIX Working Group
specifications). base64 encoding is required for MIME e-mail; no
encoding is necessary for HTTP.
Security considerations:
This MIME type may be used to transport Public-Key Infrastructure
(PKI) messages between PKI entities. These messages are defined by
the IETF PKIX Working Group and are used to establish and maintain an
Internet X.509 PKI. There is no requirement for specific security
mechanisms to be applied at this level if the PKI messages themselves
are protected as defined in the PKIX specifications.
Interoperability considerations: -
Published specification: this document
Applications which use this media type:
Applications using certificate management, operational, or ancillary
protocols (as defined by the IETF PKIX Working Group) to send PKI
messages via E-Mail or HTTP.
Additional information:
Magic number (s): -
File extension (s): ".PKI"
Macintosh File Type Code (s): -
Person and email address to contact for further information:
Carlisle Adams, cadams@entrust.com
Intended usage: COMMON
Author/Change controller: Carlisle Adams
Adams & Farrell Expires Oct. 2003 [Page 91]
Full Copyright Statement
Copyright (C) The Internet Society (2001). 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. 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 must be
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.
Adams & Farrell Expires Oct. 2003 [Page 92]