rfc2559.txt

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Network Working Group                                      S. Boeyen
Request for Comments: 2559                                   Entrust
Updates: 1778                                               T. Howes
Category: Standards Track                                   Netscape
                                                          P. Richard
                                                               Xcert
                                                          April 1999


                Internet X.509 Public Key Infrastructure
                     Operational Protocols - LDAPv2

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 (1999).  All Rights Reserved.

1.  Abstract

   The protocol described in this document is designed to satisfy some
   of the operational requirements within the Internet X.509 Public Key
   Infrastructure (IPKI).  Specifically, this document addresses
   requirements to provide access to Public Key Infrastructure (PKI)
   repositories for the purposes of retrieving PKI information and
   managing that same information.  The mechanism described in this
   document is based on the Lightweight Directory Access Protocol (LDAP)
   v2, defined in RFC 1777, defining a profile of that protocol for use
   within the IPKI and updates encodings for certificates and revocation
   lists from RFC 1778. Additional mechanisms addressing PKIX
   operational requirements are specified in separate documents.

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

2.  Introduction

   This specification is part of a multi-part standard for development
   of a Public Key Infrastructure (PKI) for the Internet. This
   specification addresses requirements to provide retrieval of X.509
   PKI information, including certificates and CRLs from a repository.
   This specification also addresses requirements to add, delete and



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   modify PKI information in a repository. A profile based on the LDAP
   version 2 protocol is provided to satisfy these requirements.

3.  Model

   The PKI components, as defined in PKIX Part 1, which are involved in
   PKIX operational protocol interactions include:

      -  End Entities
      -  Certification Authorities (CA)
      -  Repository

   End entities and CAs using LDAPv2, retrieve PKI information from the
   repository using a subset of the LDAPv2 protocol.

   CAs populate the repository with PKI information using a subset of
   the LDAPv2 protocol.

4.  Lightweight Directory Access Protocol (LDAP)

   The following sections examine the retrieval of PKI information from
   a repository and management of PKI information in a repository. A
   profile of the LDAPv2 protocol is defined for providing these
   services.

   Section 5 satisfies the requirement to retrieve PKI information (a
   certificate, CRL, or other information of interest) from an entry in
   the repository, where the retrieving entity (either an end entity or
   a CA) has knowledge of the name of the entry. This is termed
   "repository read".

   Section 6 satisfies the same requirement as 5 for the situation where
   the name of the entry is not known, but some other related
   information which may optionally be used as a filter against
   candidate entries in the repository, is known.  This is termed
   "repository search".

   Section 7 satisfies the requirement of CAs to add, delete and modify
   PKI information information (a certificate, CRL, or other information
   of interest)in the repository. This is termed "repository modify".

   The subset of LDAPv2 needed to support each of these functions is
   described below.  Note that the repository search service is a
   superset of the repository read service in terms of the LDAPv2
   functionality needed.

   Note that all tags are implicit by default in the ASN.1 definitions
   that follow.



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5.  LDAP Repository Read

   To retrieve information from an entry corresponding to the subject or
   issuer name of a certificate, requires a subset of the following
   three LDAP operations:

     BindRequest (and BindResponse)
     SearchRequest (and SearchResponse)
     UnbindRequest

   The subset of each REQUIRED operation is given below.

5.1.  Bind

5.1.1.  Bind Request

   The full LDAP v2 Bind Request is defined in RFC 1777.

   An application providing a LDAP repository read service MUST
   implement the following subset of this operation:

      BindRequest ::=
        [APPLICATION 0] SEQUENCE {
           version      INTEGER (2),
           name         LDAPDN, -- MUST accept NULL LDAPDN
           simpleauth [0] OCTET STRING  -- MUST accept NULL simple
           }

   An application providing a LDAP repository read service MAY implement
   other aspects of the BindRequest as well.

   Different services may have different security requirements.  Some
   services may allow anonymous search, others may require
   authentication. Those services allowing anonymous search may choose
   only to allow search based on certain criteria and not others.

   A LDAP repository read service SHOULD implement some level of
   anonymous search access. A LDAP repository read service MAY implement
   authenticated search access.

5.1.2.  Bind Response

   The full LDAPv2 BindResponse is described in RFC 1777.

   An application providing a LDAP repository read service MUST
   implement this entire protocol element, though only the following
   error codes may be returned from a Bind operation:




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       success                      (0),
       operationsError              (1),
       protocolError                (2),
       authMethodNotSupported       (7),
       noSuchObject                 (32),
       invalidDNSyntax              (34),
       inappropriateAuthentication  (48),
       invalidCredentials           (49),
       busy                         (51),
       unavailable                  (52),
       unwillingToPerform           (53),
       other                        (80)

5.2.  Search

5.2.1.  Search Request

   The full LDAPv2 SearchRequest is defined in RFC 1777.

   An application providing a LDAP repository read service MUST
   implement the following subset of the SearchRequest.

      SearchRequest ::=
        [APPLICATION 3] SEQUENCE {
           baseObject     LDAPDN,
           scope             ENUMERATED {
                             baseObject   (0),
                                        },
           derefAliases   ENUMERATED {
                             neverDerefAliases   (0),
                                     },
           sizeLimit      INTEGER (0),
           timeLimit      INTEGER (0),
           attrsOnly      BOOLEAN, -- FALSE only
           filter         Filter,
           attributes     SEQUENCE OF AttributeType
                               }

      Filter ::=
        CHOICE {
          present        [7] AttributeType, -- "objectclass" only
                 }

   This subset of the LDAPv2 SearchRequest allows the LDAPv2 "read"
   operation: a base object search with a filter testing for the
   existence of the objectClass attribute.





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   An application providing a LDAP repository read service MAY implement
   other aspects of the SearchRequest as well.

5.2.2.

   The full LDAPv2 SearchResponse is defined in RFC 1777.

   An application providing a LDAP repository read service over LDAPv2
   MUST implement the full SearchResponse.

   Note that in the case of multivalued attributes such as
   userCertificate a SearchResponse containing this attribute will
   include all values, assuming the requester has sufficient access
   permissions.  The application/relying party may need to select an
   appropriate value to be used. Also note that retrieval of a
   certificate from a named entry does not guarantee that the
   certificate will include that same Distinguished Name (DN) and in
   some cases the subject DN in the certificate may be NULL.

5.3.  Unbind

   The full LDAPv2 UnbindRequest is defined in RFC 1777.

   An application providing a LDAP repository read service MUST
   implement the full UnbindRequest.

6.  LDAP Repository Search

   To search, using arbitrary criteria, for an entry in a repository
   containing a certificate, CRL, or other information of interest,
   requires a subset of the following three LDAP operations:

     BindRequest (and BindResponse)
     SearchRequest (and SearchResponse)
     UnbindRequest

   The subset of each operation REQUIRED is given below.

6.1.  Bind

   The BindRequest and BindResponse subsets needed are the same as those
   described in Section 5.1.

   The full LDAP v2 Bind Request is defined in RFC 1777.







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6.2.  Search

6.2.1.  Search Request

   The full LDAPv2 SearchRequest is defined in RFC 1777.

   An application providing a LDAP repository search service MUST
   implement the following subset of the SearchRequest protocol unit.

      SearchRequest ::=
        [APPLICATION 3] SEQUENCE {
           baseObject     LDAPDN,
           scope          ENUMERATED {
                               baseObject     (0),
                               singleLevel    (1),
                               wholeSubtree   (2)
                                     },
           derefAliases   ENUMERATED {
                               neverDerefAliases     (0),
                                     },
           sizeLimit      INTEGER (0 .. maxInt),
           timeLimit      INTEGER (0 .. maxInt),
           attrsOnly      BOOLEAN,  -- FALSE only
           filter         Filter,
           attributes     SEQUENCE OF AttributeType
                                }

   All aspects of the SearchRequest MUST be supported, except for the
   following:

   - Only the neverDerefAliases value of derefAliases needs to be
     supported

   - Only the FALSE value for attrsOnly needs to be supported

   This subset provides a more general search capability.  It is a
   superset of the SearchRequest subset defined in Section 5.2.1. The
   elements added to this service are:

   - singleLevel and wholeSubtree scope needs to be supported

   - sizeLimit is included

   - timeLimit is included

   - Enhanced filter capability





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   An application providing a LDAP repository search service MAY
   implement other aspects of the SearchRequest as well.

6.2.2.  Search Response

   The full LDAPv2 SearchResponse is defined in RFC 1777.

   An application providing a LDAP repository search service over LDAPv2
   MUST implement the full SearchResponse.

6.3.  Unbind

   An application providing a LDAP repository search service MUST
   implement the full UnbindRequest.

7.  LDAP Repository Modify

   To add, delete and modify PKI information in a repository  requires a
   subset of the following LDAP operations:

     BindRequest (and BindResponse)
     ModifyRequest (and ModifyResponse)
     AddRequest (and AddResponse)
     DelRequest (and DelResponse