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IETF RFC 5917
Clearance Sponsor Attribute
Last modified on Saturday, June 5th, 2010
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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/RFC 5917.
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 [RFC 5280] and attribute
certificates [RFC 5755]. This attribute is only meaningful as a
companion of the clearance attribute [RFC 5755] [RFC 5912]. 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 [RFC 3114] 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 [RFC 5280]. 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 [RFC 5280]
and attribute certificates [RFC 5755]. 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 [RFC 2119].
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 [RFC 5755] [RFC 5912] 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
[RFC 5280], which MUST use the UTF8String CHOICE, with a minimum size
of 1 character and a maximum of 64 characters.
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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
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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
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC 5280] 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.
[RFC 5755] Farrell, S., Housley, R., and S. Turner, "An Internet
Attribute Certificate Profile for Authorization", RFC
5755, January 2010.
[RFC 5912] 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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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
[RFC 3114] Nicolls, W., "Implementing Company Classification Policy
with the S/MIME Security Label", RFC 3114, May 2002.
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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 [RFC 5912]
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 [RFC 5912]
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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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
Turner Informational PAGE 7
Clearance Sponsor Attribute
RFC TOTAL SIZE: 11618 bytes
PUBLICATION DATE: Saturday, June 5th, 2010
LEGAL RIGHTS: The IETF Trust (see BCP 78)
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