Network Working Group                                        M. Mealling
Request for Comments: 3622                                VeriSign, Inc.
Category: Informational                                    February 2004

              A Uniform Resource Name (URN) Namespace for
                     the Liberty Alliance Project

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.


   This document describes a Uniform Resource Name (URN) namespace that
   will identify various objects within the Liberty Architecture for
   federated network identity.

1.  Introduction

   The Liberty Architecture seeks to provide federated network identity
   in such a way that enhances security, privacy and trust; thus
   creating a networked world across which individuals and businesses
   can engage in virtually any transaction without compromising the
   privacy and security of vital identity information.

   One fundamental component of this architecture is its use of XML [5],
   and specifically, XML Schema [7] and Namespaces [6].  These
   components require identifiers that will live far beyond the lifetime
   of the organization that produced them.  As such, a URN namespace for
   those components that adheres to the assumptions and policies of the
   Liberty specification is required.

   This namespace specification is for a formal namespace.

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RFC 3622               The Liberty URN Namespace           February 2004

2.  Specification Template

   Namespace ID:

      "liberty" requested.

   Registration Information:

      Registration Version Number: 1

      Registration Date: 2003-04-01

   Declared registrant of the namespace:

      Liberty Alliance Project

      c/o IEEE-ISTO

      445 Hoes Lane

      Piscataway, NJ 08855-1331, USA

   Declaration of structure:

      The Namespace Specific Strings (NSS) of all URNs assigned by
      Liberty will conform to the syntax defined in section 2.2 of RFC
      2141 [1].  In addition, all Liberty URN NSSs will consist of a
      left-to-right series of tokens delimited by colons.  The left-to-
      right sequence of colon-delimited tokens corresponds to descending
      nodes in a tree.  To the right of the lowest naming authority node
      there may be zero, one or more levels of hierarchical (although
      not in the RFC 2396 [2] sense of 'hierarchy') naming nodes
      terminating in a rightmost leaf node.  See the section entitled
      "Identifier assignment" below for more on the semantics of NSSs.
      This syntax convention is captured in the following normative ABNF
      [4] rules for Liberty NSSs:

      Liberty-NSS        =   1*(subStChar) 0*(":" 1*(subStChar))
      subStChar       =   trans / "%" HEXDIG HEXDIG
      trans           =   ALPHA / DIGIT / other / reserved
      other           =   "(" / ")" / "+" / "," / "-" / "." /
                          "=" / "@" / ";" / "$" /
                          "_" / "!" / "*" / "'"
      reserved        =   "%" / "/" / "?" / "#"

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RFC 3622               The Liberty URN Namespace           February 2004

      The exclusion of the colon from the list of "other" characters
      means that the colon can only occur as a delimiter between string
      tokens.  Note that this ABNF rule set guarantees that any valid
      Liberty NSS is also a valid RFC 2141 NSS.

      For example:


   Relevant ancillary documentation:

      Liberty Architecture Overview [3]

      Version 1.1

      Liberty Alliance Project

      January 15, 2003

   Identifier uniqueness considerations:

      Identifiers are assigned by the Liberty Project within its various
      standards.  In the process of publishing a specification all newly
      minted names are checked against the record of previously assigned

   Identifier persistence considerations:

      The assignment process guarantees that names are not reassigned
      and that the binding between the name and its resource is
      permanent, regardless of any standards or organizational changes.

   Process of identifier assignment:

      Names are assigned by the Liberty standards publication process.

   Process of identifier resolution:

      At this time no resolution mechanism is specified.

   Rules for Lexical Equivalence:

      Lexical equivalence of two Liberty namespace specific strings
      (NSSs) is defined as an exact, case-sensitive string match.  The
      Liberty Alliance will assign names of immediately subordinate

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RFC 3622               The Liberty URN Namespace           February 2004

      naming authorities in a case-insensitive fashion, so that there
      will not be two Liberty-subordinate naming authorities whose names
      differ only in case.

   Conformance with URN Syntax:

      There are no additional characters reserved.

   Validation mechanism:

      None other than verifying with the correct Liberty specifications.



3.  IANA Considerations

   This document includes a URN Namespace registration that has been
   entered into the IANA registry for URN NIDs.

4.  Community Considerations

   While there is no resolution mechanism for this namespace, the names
   themselves are used in public implementations of the Liberty
   specifications.  There are circumstances where objects from the
   Liberty system will become exposed to the general Internet.  In these
   cases, the use of the Liberty namespace will provide general
   interoperability benefits to the Internet at large.  Additionally,
   there may be subcomponents of the Liberty specifications that may be
   adopted by other standards, in which case the URNs used to identify
   those components and specifications can be easily used to enhance
   other, non-Liberty based, systems.

5.  Security Considerations

   Since there is no defined resolution mechanism for Liberty URNs it is
   difficult to authenticate the fact that a given namespace actually
   adheres to the standard, thus applications should be careful to not
   take some unverified sources assertion that what it is sending
   adheres to what the actual URN is assigned to.

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RFC 3622               The Liberty URN Namespace           February 2004

6.  References

6.1.  Normative References

   [1]  Moats, R., "URN Syntax", RFC 2141, May 1997.

   [2]  Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource
        Identifiers (URI): Generic Syntax", RFC 2396, August 1998.

   [3]  Hodges, J. and T. Watson, "Liberty Architecture Overview",
        Liberty 1.1, January 2003,

6.2.  Informative References

   [4]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
        Specifications: ABNF", RFC 2234, November 1997.

   [5]  Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler,
        "Extensible Markup Language (XML) 1.0 (2nd ed)", W3C REC-xml,
        October 2000, <>.

   [6]  Bray, T., Hollander, D. and A. Layman, "Namespaces in XML", W3C
        REC-xml-names, January 1999, <

   [7]  Thompson, H., Beech, D., Maloney, M. and N. Mendelsohn, "XML
        Schema Part 1: Structures", W3C REC-xmlschema-1, May 2001,

7.  Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   intellectual property or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; neither does it represent that it
   has made any effort to identify any such rights. Information on the
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in BCP-11. Copies of
   claims of rights made available for publication and any assurances of
   licenses to be made available, or the result of an attempt made to
   obtain a general license or permission for the use of such
   proprietary rights by implementors or users of this specification can
   be obtained from the IETF Secretariat.

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RFC 3622               The Liberty URN Namespace           February 2004

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights which may cover technology that may be required to practice
   this standard. Please address the information to the IETF Executive

8.  Author's Address

   Michael Mealling
   VeriSign, Inc.
   21345 Ridgetop Circle
   Dulles, VA  20166

   Phone: +1 678 581 9656

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RFC 3622               The Liberty URN Namespace           February 2004

9.  Full Copyright Statement

   Copyright (C) The Internet Society (2004).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
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   included on all such copies and derivative works.  However, this
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   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assignees.

   This document and the information contained herein is provided on an


   Funding for the RFC Editor function is currently provided by the
   Internet Society.

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