rfc2797.txt

PKIX的RFC英文文档

Network Working Group                                            M. Myers
Request for Comments: 2797                                       VeriSign
Category: Standards Track                                          X. Liu
                                                                    Cisco
                                                                J. Schaad
                                                                Microsoft
                                                             J. Weinstein
                                                               April 2000


                Certificate Management Messages over CMS

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

Abstract

   This document defines a Certificate Management protocol using CMS
   (CMC).  This protocol addresses two immediate needs within the
   Internet PKI community:

   1. The need for an interface to public key certification products and
      services based on [CMS] and [PKCS10], and
   2. The need in [SMIMEV3] for a certificate enrollment protocol for
      DSA-signed certificates with Diffie-Hellman public keys.

   A small number of additional services are defined to supplement the
   core certificate request service.

   Throughout this specification the term CMS is used to refer to both
   [CMS] and [PKCS7].  For both signedData and envelopedData, CMS is a
   superset of the PKCS7. In general, the use of PKCS7 in this document
   is aligned to the Cryptographic Message Syntax [CMS] that provides a
   superset of the PKCS7 syntax. The term CMC refers to this
   specification.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC 2119].



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RFC 2797        Certificate Management Messages over CMS      April 2000


1.  Protocol Requirements

   -  The protocol is to be based as much as possible on the existing
      CMS, PKCS#10 and CRMF specifications.
   -  The protocol must support the current industry practice of a
      PKCS#10 request followed by a PKCS#7 response as a subset of the
      protocol.
   -  The protocol needs to easily support the multi-key enrollment
      protocols required by S/MIME and other groups.
   -  The protocol must supply a way of doing all operations in a
      single-round trip.  When this is not possible the number of round
      trips is to be minimized.
   -  The protocol will be designed such that all key generation can
      occur on the client.
   -  The mandatory algorithms must superset the required algorithms for
      S/MIME.
   -  The protocol will contain POP methods. Optional provisions for
      multiple-round trip POP will be made if necessary.
   -  The protocol will support deferred and pending responses to
      certificate request for cases where external procedures are
      required to issue a certificate.
   -  The protocol needs to support arbitrary chains of local
      registration authorities as intermediaries between certificate
      requesters and issuers.

2.  Protocol Overview

   An enrollment transaction in this specification is generally composed
   of a single round trip of messages.  In the simplest case an
   enrollment request is sent from the client to the server and an
   enrollment response is then returned from the server to the client.
   In some more complicated cases, such as delayed certificate issuance
   and polling for responses, more than one round trip is required.

   This specification supports two different request messages and two
   different response messages.

   Public key certification requests can be based on either the PKCS10
   or CRMF object.  The two different request messages are (a) the bare
   PKCS10 (in the event that no other services are needed), and (b) the
   PKCS10 or CRMF message wrapped in a CMS encapsulation as part of a
   PKIData object.

   Public key certification responses are based on the CMS signedData
   object.  The response may be either (a) a degenerate CMS signedData
   object (in the event no other services are needed), or (b) a
   ResponseBody object wrapped in a CMS signedData object.




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RFC 2797        Certificate Management Messages over CMS      April 2000


   No special services are provided for doing either renewal (new
   certificates with the same key) or re-keying (new certificates on new
   keys) of clients.  Instead a renewal/re-key message looks the same as
   any enrollment message, with the identity proof being supplied by
   existing certificates from the CA.

   A provision exists for Local Registration Authorities (LRAs) to
   participate in the protocol by taking client enrollment messages,
   wrapping them in a second layer of enrollment message with additional
   requirements or statements from the LRA and then passing this new
   expanded request on to the Certification Authority.

   This specification makes no assumptions about the underlying
   transport mechanism.  The use of CMS is not meant to imply an email-
   based transport.

   Optional services available through this specification are
   transaction management, replay detection (through nonces), deferred
   certificate issuance, certificate revocation requests and
   certificate/CRL retrieval.

2.1  Terminology

   There are several different terms, abbreviations and acronyms used in
   this document that we define here for convenience and consistency of
   usage:

   "End-Entity" (EE) refers to the entity that owns a key pair and for
      whom a certificate is issued.
   "LRA" or "RA" refers to a (Local) Registration Authority.  A
      registration authority acts as an intermediary between an End-
      Entity and a Certification Authority.  Multiple RAs can exist
      between the End-Entity and the Certification Authority.
   "CA" refers to a Certification Authority.  A Certification Authority
      is the entity that performs the actual issuance of a certificate.
   "Client" refers to an entity that creates a PKI request.  In this
      document both RAs and End-Entities can be clients.
   "Server" refers to the entities that process PKI requests and create
      PKI responses.  CAs and RAs can be servers in this document.
   "PKCS#10" refers the Public Key Cryptography Standard #10.  This is
      one of a set of standards defined by RSA Laboratories in the
      1980s.  PKCS#10 defines a Certificate Request Message syntax.
   "CRMF" refers to the Certificate Request Message Format RFC [CRMF].
      We are using certificate request message format defined in this
      document as part of our management protocol.
   "CMS" refers to the Cryptographic Message Syntax RFC [CMS].  This
      document provides for basic cryptographic services including
      encryption and signing with and without key management.



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RFC 2797        Certificate Management Messages over CMS      April 2000


   "POP" is an acronym for "Proof of Possession".  POP refers to a value
      that can be used to prove that the private key corresponding to a
      public key is in the possession and can be used by an end-entity.
   "Transport wrapper" refers to the outermost CMS wrapping layer.

2.2  Protocol Flow Charts

   Figure 1 shows the Simple Enrollment Request and Response messages.
   The contents of these messages are detailed in Sections 4.1 and 4.3
   below.

    Simple PKI Request                      Simple PKI Response
    -------------------------               --------------------------

    +----------+                            +------------------+
    | PKCS #10 |                            | CMS "certs-only" |
    +----------+--------------+             |     message      |
    |                         |             +------------------+------+
    | Certificate Request     |             |                         |
    |                         |             | CMS Signed Data,        |
    | Subject Name            |             |   no signerInfo         |
    | Subject Public Key Info |             |                         |
    |   (K_PUB)               |             | signedData contains one |
    | Attributes              |             | or more certificates in |
    |                         |             | the "certificates"      |
    +-----------+-------------+             | portion of the          |
                | signed with |             | signedData.             |
                | matching    |             |                         |
                | K_PRIV      |             | encapsulatedContentInfo |
                +-------------+             | is empty.               |
                                            |                         |
                                            +--------------+----------+
                                                           | unsigned |
                                                           +----------+

               Figure 1: Simple PKI Request and Response Messages















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    Full PKI Request                        Full PKI Response
    -----------------------                 ------------------------

    +----------------+                      +----------------+
    | CMS signedData |                      | CMS signedData |
    |     object     |                      |     object     |
    +----------------+--------+             +----------------+--------+
    |                         |             |                         |
    | PKIData object          |             | ResponseBody object     |
    |                         |             |                         |
    | Sequence of:            |             | Sequence of:            |
    | <enrollment attribute>* |             | <enrollment attribute>* |
    | <certification request>*|             | <CMS object>*           |
    | <CMS objects>*          |             | <other message>*        |
    | <other message>*        |             |                         |
    |                         |             | where * == zero or more |
    | where * == zero or more |             |                         |
    |                         |             | All certificates issued |
    | Certificate requests    |             | as part of the response |
    | are CRMF or PKCS#10     |             | are included in the     |
    | objects. Attributes are |             | "certificates" portion  |
    | (OID, ANY defined by    |             | of the signedData.      |
    | OID) pairs.             |             | Relevant CA certs and   |
    |                         |             | CRLs can be included as |
    +-------+-----------------+             | well.                   |
            | signed (keypair |             |                         |
            | used may be pre-|             +---------+---------------+
            | existing or     |                       | signed by the |
            | identified in   |                       | CA or an LRA  |
            | the request)    |                       +---------------+
            +-----------------+

               Figure 2: Full PKI Request and Response Messages

   Figure 2 shows the Full Enrollment Request and Response messages.
   The contents of these messages are detailed in Sections 4.2 and 4.4
   below.

3.  Protocol Elements

   This section covers each of the different elements that may be used
   to construct enrollment request and enrollment response messages.
   Section 4 will cover how to build the enrollment request and response
   messages.







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RFC 2797        Certificate Management Messages over CMS      April 2000


3.1  PKIData Object

   The new content object PKIData has been defined for this protocol.
   This new object is used as the body of the full PKI request message.
   The new body is identified by:

     id-cct-PKIData  OBJECT IDENTIFIER ::= { id-cct 2 }

   The ASN.1 structure corresponding to this new content type is:

   PKIData ::= SEQUENCE {
         controlSequence    SEQUENCE SIZE(0..MAX) OF TaggedAttribute,
         reqSequence        SEQUENCE SIZE(0..MAX) OF TaggedRequest,
         cmsSequence        SEQUENCE SIZE(0..MAX) OF TaggedContentInfo,
         otherMsgSequence   SEQUENCE SIZE(0..MAX) OF OtherMsg
   }

   -- controlSequence consists of a sequence of control attributes.  The
   control attributes defined in this document are found in section 5.
   As control sequences are defined by OIDs, other parties can define
   additional control attributes. Unrecognized OIDs MUST result in no
   part of the request being successfully processed.