Network Working Group                                        M. Mealling
Internet-Draft                                            VeriSign, Inc.
Expires: October 10, 2003                                 April 11, 2003

            A URN Namespace For The Liberty Alliance Project

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
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Copyright Notice

   Copyright (C) The Internet Society (2003). All Rights Reserved.


   This document describes a URN namespace that will identify various
   objects within the Liberty Architecture for federated network

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.

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   One fundamental component of this architecture is its use of XML [4],
   and specifically, XML Schema [6] and Namespaces [5]. 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.

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
         RFC2141 [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

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         authority node there may be zero, one or more levels of
         hierarchical (although not in the RFC  2396 [3] 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 [2] rules for Liberty NSSs:

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

          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 RFC2141 NSS.

         For example:


   Relevant ancillary documentation:

         Liberty Architecture Overview [7]

         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 names.

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   Identifier persistence considerations:

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

   Process of identifier assignment:

         Names are assigned by the Liberty standards publication

   Process of identifier resolution:

         At this time no resolution mechanism is specified.

   Rules for Lexical Equivalence:

         The entire URN is case-insensitive.

   Conformance with URN Syntax:

         There are no additional characters reserved.

   Validation mechanism:

         None other than verifying with the correct Liberty



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3. IANA Considerations

   This document includes a URN Namespace registration that is to be
   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 be careful to
   not take some unverified sources assertion that what it is sending
   adheres to what the actual URN is assigned to.


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

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

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

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

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

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

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

Author's Address

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

   Phone: +1 678 581 9656

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

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