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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.

Turner Informational [Page 1] RFC 5917 Clearance Sponsor Attribute June 2010

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.

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 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

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 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.

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 [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.

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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

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 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

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