Internet Engineering Task Force (IETF)                         S. Turner
Request for Comments: 5917                                          IECA
Category: Informational                                        June 2010
ISSN: 2070-1721


                      Clearance Sponsor Attribute

Abstract

   This document defines the clearance sponsor attribute.  It indicates
   the entity that sponsored (i.e., granted) the clearance.  This
   attribute is intended for use in public key certificates and
   attribute certificates that also include the clearance attribute.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any
   errata, and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5917.

Copyright Notice

   Copyright (c) 2010 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

1.  Introduction

   This document specifies the clearance sponsor attribute.  It is
   included in public key certificates [RFC5280] and attribute
   certificates [RFC5755].  This attribute is only meaningful as a
   companion of the clearance attribute [RFC5755] [RFC5912].  The
   clearance sponsor is the entity (e.g., agency, department, or
   organization) that granted the clearance to the subject named in the
   certificate.  For example, the clearance sponsor for a subject
   asserting the Amoco clearance values [RFC3114] could be
   "Engineering".

   This attribute may be used in automated authorization decisions.  For
   example, a web server deciding whether to allow a user access could
   check that the clearance sponsor present in the user's certificate is
   on an "approved" list.  This check is performed in addition to
   certification path validation [RFC5280].  The mechanism for managing
   the "approved" list is beyond the scope of this document.

   NOTE: This document does not provide an equivalent Lightweight
   Directory Access Protocol (LDAP) schema specification as this
   attribute is initially targeted at public key certificates [RFC5280]
   and attribute certificates [RFC5755].  Definition of an equivalent
   LDAP schema is left to a future specification.

1.1.  Terminology

   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 [RFC2119].

1.2.  ASN.1 Syntax Notation

   The attribute is defined using ASN.1 [X.680], [X.681], [X.682], and
   [X.683].

2.  Clearance Sponsor

   The clearance sponsor attribute, which is only meaningful if the
   clearance attribute [RFC5755] [RFC5912] is also present, indicates
   the sponsor of the clearance of the subject with which this attribute
   is associated.  The clearance sponsor attribute is a DirectoryString
   [RFC5280], which MUST use the UTF8String CHOICE, with a minimum size
   of 1 character and a maximum of 64 characters.

   The following object identifier identifies the sponsor attribute:

   id-clearanceSponsor OBJECT IDENTIFIER ::= {
     joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101)
     dod(2) infosec(1) attributes(5) 68
   }

   The ASN.1 syntax for the clearance sponsor attribute is as follows:

   at-clearanceSponsor ATTRIBUTE ::= {
     TYPE                   DirectoryString { ub-clearance-sponsor }
                            ( WITH COMPONENTS { utf8String PRESENT } )
     EQUALITY MATCHING RULE caseIgnoreMatch
     IDENTIFIED BY          id-clearanceSponsor
   }

   ub-clearance-sponsor INTEGER ::= 64

   There MUST only be one value of clearanceSponsor associated with a
   particular certificate.  Distinct sponsors MUST be represented in
   separate certificates.

   When an environment uses the Clearance Sponsor attribute, it is
   important that the same representation of the sponsor be used
   throughout the environment (e.g., using the same acronym).  Further,
   the value in this attribute is not meant to be globally unique.  When
   included in certificates, it is unique within the scope of the
   issuer.

3.  Security Considerations

   If this attribute is used as part of an authorization process, the
   procedures employed by the entity that assigns each clearance sponsor
   value must ensure that the correct value is applied.  Including this
   attribute in a public key certificate or attribute certificate
   ensures that the value for the clearance sponsor is integrity
   protected.

   The certificate issuer and clearance sponsor are not necessarily the
   same entity.  If they are separate entities, then the mechanism used
   by the clearance sponsor to convey to the certificate issuer that the
   clearance sponsor did in fact grant the clearance to the subject
   needs to be protected from unauthorized modification.

   If two entities are verifying each other's certificates, they do not
   share the same issuer, and they use the same clearance sponsor value
   (e.g., a United Kingdom PKI includes "MoD" and a New Zealand PKI also
   includes "MoD"), then the relying party has two choices: 1) accept

   the two strings as equivalent, or 2) indicate the sponsor as well as
   the trust anchor.  To solve this problem, a mechanism, which is
   outside the scope of this specification, could be developed to allow
   a relying party to group together issuers that share a same context
   within which sponsor names have a unique significance.

   While values of DirectoryString can include the NUL (U+0000) code
   point, values used to represent clearance sponsors typically would
   not.  Implementations of the caseIgnoreMatch rule must, per X.501,
   consider all of the assertion value and attribute value in matching
   and hence protect against truncation attacks.

4.  References

4.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, May 2008.

   [RFC5755]  Farrell, S., Housley, R., and S. Turner, "An Internet
              Attribute Certificate Profile for Authorization", RFC
              5755, January 2010.

   [RFC5912]  Schaad, J. and P. Hoffman, "New ASN.1 Modules for the
              Public Key Infrastructure Using X.509 (PKIX)", RFC 5912,
              June 2010.

   [X.520]    ITU-T Recommendation X.520 (2002) | ISO/IEC 9594-6:2002,
              Information technology - The Directory:Selected Attribute
              Types.

   [X.680]    ITU-T Recommendation X.680 (2002) | ISO/IEC 8824-1:2002,
              Information technology - Abstract Syntax Notation One
              (ASN.1): Specification of basic notation.

   [X.681]    ITU-T Recommendation X.681 (2002) | ISO/IEC 8824-2:2002,
              Information Technology - Abstract Syntax Notation One:
              Information Object Specification.

   [X.682]    ITU-T Recommendation X.682 (2002) | ISO/IEC 8824-3:2002,
              Information Technology - Abstract Syntax Notation One:
              Constraint Specification.

   [X.683]    ITU-T Recommendation X.683 (2002) | ISO/IEC 8824-4:2002,
              Information Technology - Abstract Syntax Notation One:
              Parameterization of ASN.1 Specifications.

4.2.  Informative References

   [RFC3114]  Nicolls, W., "Implementing Company Classification Policy
              with the S/MIME Security Label", RFC 3114, May 2002.

Appendix A.  ASN.1 Module

   This appendix provides the normative ASN.1 [X.680] definitions for
   the structures described in this specification using ASN.1 as defined
   in [X.680], [X.681], [X.682], and [X.683].

   ClearanceSponsorAttribute-2008
     { joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101)
       dod(2) infosec(1) modules(0)
       id-clearanceSponsorAttribute-2008(35) }

   DEFINITIONS IMPLICIT TAGS ::=

   BEGIN

   -- EXPORTS ALL --

   IMPORTS

   -- Imports from New PKIX ASN.1 [RFC5912]

     DirectoryString
       PKIX1Explicit-2009
         { iso(1) identified-organization(3) dod(6) internet(1)
           security(5) mechanisms(5) pkix(7) id-mod(0)
           id-pkix1-explicit-02(51) }

   -- Imports from New PKIX ASN.1 [RFC5912]

     ATTRIBUTE
       FROM PKIX-CommonTypes-2009
         { iso(1) identified-organization(3) dod(6) internet(1)
           security(5) mechanisms(5) pkix(7) id-mod(0)
           id-mod-pkixCommon-02(57) }

   -- Imports from ITU-T X.520 [X.520]

     caseIgnoreMatch
       FROM SelectedAttributeTypes
         { joint-iso-itu-t ds(5) module(1) selectedAttributeTypes(5) 4 }

   ;

   -- sponsor attribute OID and syntax

   id-clearanceSponsor OBJECT IDENTIFIER ::= {
     joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101)
     dod(2) infosec(1) attributes(5) 68

   }

   at-clearanceSponsor ATTRIBUTE ::= {
     TYPE                   DirectoryString { ub-clearance-sponsor }
                            ( WITH COMPONENTS { utf8String PRESENT } )
     EQUALITY MATCHING RULE caseIgnoreMatch
     IDENTIFIED BY          id-clearanceSponsor
   }

   ub-clearance-sponsor INTEGER ::= 64

   END

Author's Address

   Sean Turner
   IECA, Inc.
   3057 Nutley Street, Suite 106
   Fairfax, VA 22031
   USA

   EMail: turners@ieca.com