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Internet Engineering Task Force (IETF)                         S. TurnerRequest for Comments: 5917                                          IECACategory: Informational                                        June 2010ISSN: 2070-1721Clearance Sponsor AttributeAbstract   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; seeSection 2 of RFC 5741.   Information about the current status of this document, any   errata, and how to provide feedback on it may be obtained athttp://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 toBCP 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 20101.  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.Turner                        Informational                     [Page 2]

RFC 5917               Clearance Sponsor Attribute             June 2010   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) acceptTurner                        Informational                     [Page 3]

RFC 5917               Clearance Sponsor Attribute             June 2010   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.  References4.1.  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",RFC5755, 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.Turner                        Informational                     [Page 4]

RFC 5917               Clearance Sponsor Attribute             June 2010   [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.Turner                        Informational                     [Page 5]

RFC 5917               Clearance Sponsor Attribute             June 2010Appendix 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) 68Turner                        Informational                     [Page 6]

RFC 5917               Clearance Sponsor Attribute             June 2010   }   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   ENDAuthor's Address   Sean Turner   IECA, Inc.   3057 Nutley Street, Suite 106   Fairfax, VA 22031   USA   EMail: turners@ieca.comTurner                        Informational                     [Page 7]