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
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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. 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) accept Turner 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. 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. 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 2010 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 Turner 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
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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