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Versions: (RFC 2510) 00 01 02 03 04 05 06 07 08 09 RFC 4210

Internet Draft                                                   C. Adams
PKIX Working Group                                          Entrust, Inc.
December, 2001                                                 S. Farrell
Expires in 6 Months                                Baltimore Technologies


                Internet X.509 Public Key Infrastructure
                    Certificate Management Protocols
                   <draft-ietf-pkix-rfc2510bis-06.txt>

Status of this Memo


   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that other
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
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   This Internet-Draft will expire in June, 2002.  Comments or
   suggestions for improvement may be made on the "ietf-pkix" mailing
   list, or directly to the authors.

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.


Abstract

   This document describes the Internet X.509 Public Key Infrastructure
   (PKI) Certificate Management Protocols. Protocol messages are defined
   for all relevant aspects of certificate creation and management.
   Note that "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].


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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

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

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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




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   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.


























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      +---+     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.






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      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.



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   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





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   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. 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.











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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



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   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).





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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.





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   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.









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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.







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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


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   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





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         -- 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.






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   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.

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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 June 2002                  [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 June 2002                  [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.

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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





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         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 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





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   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

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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.


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   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      <-

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   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.

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   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 public key.  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).



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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



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   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.)


















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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































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   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.











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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.


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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.












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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.

   [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.

   [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.

   [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).




Adams & Farrell               Expires June 2002                  [Page 57]

   [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.

   [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.



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 June 2002                  [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).

















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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 June 2002                  [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")

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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).



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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 June 2002                  [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


































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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

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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 June 2002                  [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 June 2002                  [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


































Adams & Farrell               Expires June 2002                  [Page 68]

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 June 2002                  [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 June 2002                  [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 June 2002                  [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 June 2002                  [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











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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


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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.

















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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).


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 - 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).























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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

      ;













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--  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

















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      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





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      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),

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      -- 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

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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 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
  }















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  OOBCert ::= CMPCertificate

  OOBCertHash ::= SEQUENCE {
      hashAlg     [0] AlgorithmIdentifier     OPTIONAL,
      certId      [1] CertId                  OPTIONAL,
      hashVal         BIT STRING
      -- hashVal is calculated over DER encoding of the
      -- subjectPublicKey field of the corresponding cert.
  }

  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 June 2002                  [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













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  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.






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  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 June 2002                  [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 June 2002                  [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
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   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
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   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.


























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