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Versions: 00 01 02 03 04 05 06 rfc6711                     Informational
Network Working Group                                       L. Johansson
Internet-Draft                                                  NORDUNet
Intended status: Informational                               May 4, 2012
Expires: November 5, 2012


         An IANA registry for Level of Assurance (LoA) Profiles
                    draft-johansson-loa-registry-06

Abstract

   This document establishes an IANA registry for Level of Assurance
   (LoA) Profiles.  The registry is intended to be used as an aid to
   discovering such LoA definitions in protocols that use an LoA
   concept, including SAML 2.0 and OpenID Connect.

Requirements Language

   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].

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 5, 2012.

Copyright Notice

   Copyright (c) 2012 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



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   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.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Name of Registry . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Registration Template  . . . . . . . . . . . . . . . . . . . .  4
     3.1.  Example Registration . . . . . . . . . . . . . . . . . . .  5
     3.2.  Note on the Example  . . . . . . . . . . . . . . . . . . .  6
   4.  Registration Policy  . . . . . . . . . . . . . . . . . . . . .  6
     4.1.  Reviewer Expectations  . . . . . . . . . . . . . . . . . .  7
   5.  Registry Semantics . . . . . . . . . . . . . . . . . . . . . .  7
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  8
   9.  Changes  . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     9.1.  since -00  . . . . . . . . . . . . . . . . . . . . . . . .  8
     9.2.  since -01  . . . . . . . . . . . . . . . . . . . . . . . .  8
     9.3.  since -02  . . . . . . . . . . . . . . . . . . . . . . . .  9
     9.4.  since -03  . . . . . . . . . . . . . . . . . . . . . . . .  9
     9.5.  since -04  . . . . . . . . . . . . . . . . . . . . . . . .  9
     9.6.  since -05  . . . . . . . . . . . . . . . . . . . . . . . .  9
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 10
     10.2. Informative References . . . . . . . . . . . . . . . . . . 10
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10




















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1.  Introduction

   This document establishes an IANA registry for Level of Assurance
   Profiles.

   Quoting from sstc.saml-assurance-profile
   [OASIS.sstc.saml-assurance-profile] we find the following definition
   of the concept of 'level of assurance':

   _Many existing (and potential) SAML federation deployments have
   adopted a "levels of assurance" (or LOA) model for categorizing the
   wide variety of authentication methods into a small number of levels,
   typically based on some notion of the strength of the authentication.
   Federation members (service providers or "relying parties") then
   decide which level of assurance is required to access specific
   protected resources, based on some assessment of "value" or "risk"._

   Another definition of a 'level of assurance' is given in RFC4949
   [RFC4949] which also identifies the roots of such profiles in the
   NIST special publication series, in particular SP 800-63 [SP63].
   Level of Assurance profiles are used in various protocols, including
   the Security Assertion Markup Language (SAML) version 2.0 and OpenID
   Connect.

   Several so called trust frameworks and identity federations now
   exist, some of which define one or more Level of Assurance (LoA).
   The purpose of this specification is to create an IANA registry where
   such LoA definitions can be discovered.  While the quote above
   references SAML the notion of a "level of assurance" has gained wide-
   spread acceptance and should be treated as a protocol-independent
   concept.  The proposed IANA registry attempts to reflects this.

   Although the registry will contain URIs that reference SAML
   Authentication Context Profiles other protocols may use such URIs to
   identify levels of assurance definitions without relying on or
   transmitting their SAML XML definitions.  Use of the registry by
   protocols other than SAML is encouraged.

   For instance OpenID Connect defines the standard claim 'acr' as a
   identifier that may reference a SAML Authentication Context Class
   even though OpenID Connect is not itself based on XML or SAML.

   Protocol designers who want to reference the registry should be aware
   that registered LoAs may depend on assumptions that do not carry over
   to all protocols and that such assumptions may vary among the
   protocols for which the LoAs were originally registered.





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2.  Name of Registry

   The name of the registry shall be "Level of Assurance Profile", in
   plural "Level of Assurance Profiles".  The term LoA is an
   abbreviation of Level of Assurance.


3.  Registration Template

   The following information must be provided with each registration:

   URI:  A URI referencing a Level of Assurance Profile.  This is the
      registry key.

   Context Class:  A valid XML schema definition for the SAML 2.0 LoA
      Context Class fulfilling the requirements of sstc.saml-assurance-
      profile [OASIS.sstc.saml-assurance-profile].  The registry key
      (the URI) is the unique identifier for the Context Class.

   Name:  A string uniquely and unambiguously identifying the LoA for
      use in protocols where URIs are not appropriate.

   Informational URL:  A URL containing auxilliary information.  This
      URL must minimally reference contact information for the
      administrative authority of the level of assurance definition and
      must use either the http or https schemes.

   Note that it is possible for a single SAML Authentication Context
   Class to contain definitions of multiple URIs.  In that case a
   separate registration is to be used for each URI.  Both the name and
   the URI are to uniquely and unambigously identify the LoA.  The name
   is meant to be used in protocols where URIs are not appropriate.  In
   addition the requester is expected to provide basic contact
   information and the name of the organization on behalf of which the
   LoA definition is registered.

   The Name is defined by the following ABNF (as defined in RFC5234
   [RFC5234]):
   label = ( ALPHA / DIGIT )
   name = label 1*( label / "-" / "." / "_" )











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   The elements defined by the following ABNF productions represent a
   set of reserved values for the Name element and are not to be
   registered:
   reserved = loa / al / num
   loa = ( "l" / "L" ) ( "o" / "O" ) ( "a" / "A") *DIGIT
   al = ( "a" / "A") ( "l" / "L") *DIGIT
   num = *DIGIT
   The reason for excluding these productions is a desire to avoid a
   race to register overly generic LoA profiles under names like "AL1"
   or "LOA2".

3.1.  Example Registration

   1.  Name of requester: J. Random User

   2.  E-mail address of requester: jrandom@example.com

   3.  Organization of requester: Example Trust Frameworks LLP

   4.  Requested registration:

   URI  http://foo.example.com/assurance/loa-1

   Name  foo-loa-1

   Information URL  https://foo.example.com/assurance/

























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   SAML 2.0 Authentication Context Class Definition
   <?xml version="1.0" encoding="UTF-8"?>
   <xs:schema
       targetNamespace="http://foo.example.com/assurance/loa-1"
       xmlns:xs="http://www.w3.org/2001/XMLSchema"
       xmlns="http://foo.example.com/assurance/loa-1"
       finalDefault="extension"
       blockDefault="substitution"
       version="2.0">
     <xs:redefine
        schemaLocation="saml-schema-authn-context-loa-profile.xsd">
         <xs:annotation>
             <xs:documentation>
                 Class identifier:
                     http://foo.example.com/assurance/loa-1
                     Defines Level 1 of the Foo Assurance Framework
             </xs:documentation>
         </xs:annotation>
         <xs:complexType name="GoverningAgreementRefType">
           <xs:complexContent>
             <xs:restriction base="GoverningAgreementRefType">
               <xs:attribute name="governingAgreementRef"
                 type="xs:anyURI"
                 fixed="https://foo.example.com/assurance/"
                 use="required"/>
               </xs:restriction>
           </xs:complexContent>
         </xs:complexType>
     </xs:redefine>
   </xs:schema>

3.2.  Note on the Example

   The example is borrowed (slightly modified) from sstc.saml-assurance-
   profile [OASIS.sstc.saml-assurance-profile].  The example should not
   be registered.


4.  Registration Policy

   The registry is to be operated under the "Expert Review" policy from
   RFC5226 [RFC5226] employing a pool of experts.  IANA is kindly asked
   to do rough randomized load-balancing among the experts and also do
   an initial review of each submission to ensure that the name is and
   URI are unique within the registry.  The review criteria are outlined
   below.

   Registrations that reference multiple LoAs in a consistent set of



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   policies - for instance when a trust framework defines multiple
   levels of assurance - the registered LoA Name and URIs should be
   consistently named so that they identified as belonging to the same
   set of registrations.  For instance fruitLoA1,fruitLoA2 and fruitLoA3
   is preferred over apple,pear and banana when these Names refer to a
   single set of policies defining 3 LoAs.

4.1.  Reviewer Expectations

   The expectation of the IANA LoA Registry is that it contain
   registrations of bona fide Level of Assurance Profiles while not
   presenting a very high bar for entry.

   Expert reviewers are expected to verify that:

   o  the registration is consistent and that the provided XML fulfills
      the requirements of sstc.saml-assurance-profile
      [OASIS.sstc.saml-assurance-profile].

   o  the Name element is clearly associated with the registered LoA
      Profile and is not a reserved value.

   o  the URI and Name elements are not already registered.

   o  the Information URL can be expected to be stable and permanent.

   Note that multiple registrations may share a common Informational
   URL.

   The reviewers should exclude registrations where the Name does not
   unambiguously identify the LoA definition or where the Name is a
   simple variation on one of the reserved names.

   Expert reviewers are expected to allow registrations made in good
   faith that fulfil these requirements.


5.  Registry Semantics

   The intended use for this registry is to serve as a basis for
   discovery of LoA definitions that might for instance be used by
   protocol-specific (eg SAML 2.0 or OpenID Connect) management tools.

   Note that consumers of the registry, being implementations of
   [OASIS.sstc.saml-ass], are expected to allow configuration of LoA
   URIs at system deploy-time.  If multiple sources of LOA URIs are
   permitted in addition to the registry (eg manual input) then it is
   important to avoid collisions with URIs found in the registry.



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   The presence of an entry in the registry does not imply any semantic
   or quality beyond that which results from the review done by the
   expert reviewer as part of the registration process.


6.  IANA Considerations

   This document sets up a registry with IANA making the whole document
   a set of considerations for IANA.


7.  Security Considerations

   The registry is not a federation or trust framework.  Consumers of
   the registry are strongly advised to review the information about an
   LoA before relying on it.


8.  Acknowledgements

   RL 'Bob' Morgan, Scott Cantor, Lucy Lynch and John Bradley were
   involved in the initial discussions around this idea and contributed
   to the semantics of the registry.  The various versions of the draft
   were socialized in the Kantara Federation Interoperability WG and in
   other parts of the identity community.


9.  Changes

   Note to the RFC editor: This section should be removed before
   publication.

9.1.  since -00

   o  Clarified the security considerations wrt the status of the IANA
      registry.

   o  Text in the introduction that explains that the registry can be
      used by other protocols than SAML and that this is encouraged.

9.2.  since -01

   o  Allow for registration of short identifiers.








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9.3.  since -02

   o  Make the text less explicitly dependent on SAML.

   o  Include OpenID Connect reference.

   o  Corrected the SSTC reference

   o  Reserve numeric-only LoA names (eg '1')

9.4.  since -03

   o  comments from PROTO writeup, AD and document shepherd

   o  remove initial list of reviewers - it will be decided by IESG

   o  example registration

9.5.  since -04

   o  ABNF fixes

   o  example registration

   o  policy for consistent naming across multiple related registrations

   o  minor nits

9.6.  since -05

   o  clarified introduction by re-arranging paragraphs

   o  removed RFC2119-language

   o  clarified security considerations section

   o  clarified reviewer expectations

   o  corrected the example

   o  corrected reference to IANA Expert Review policy

   o  included ABNF reference

   o  expectations on Information URI stability

   o  limit the allowed Information URI scheme




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   o  various nits


10.  References

10.1.  Normative References

   [OASIS.sstc.saml-assurance-profile]
              Morgan, RL., Madsen, PM., and S. Cantor, "SAML V2.0
              Identity Assurance Profiles Version 1.0", November 2010.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

10.2.  Informative References

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              RFC 4949, August 2007.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [SP63]     NIST, "Electronic Authentication Guideline, NIST Special
              Publication 800-63", June 2004.


Author's Address

   Leif Johansson
   NORDUNet
   Tulegatan 11
   Stockholm
   Sweden

   Email: leifj@nordu.net












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