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ABFAB                                                         J. Howlett
Internet-Draft                                                     Janet
Intended status: Informational                                S. Hartman
Expires: August 29, 2013                               Painless Security
                                                       February 25, 2013


   A RADIUS Attribute, Binding, Profiles, Name Identifier Format, and
                     Confirmation Methods for SAML
                      draft-ietf-abfab-aaa-saml-05

Abstract

   This document specifies a RADIUS attribute, a binding, a name
   identifier format, two profiles, and two confirmation methods for the
   Security Assertion Mark-up Language (SAML).  The attribute provides
   RADIUS encapsulation of SAML protocol messages, and the binding
   describes the use of this attribute, and the SAML protocol messages
   within, with RADIUS transport.  The two profiles describe the
   application of this binding for ABFAB authentication and assertion
   query/request respectively.  The name identifier format allows a
   subject to be named using an NAI, and the subject confirmation
   methods allow queries to be issued for a principal without needing to
   explicitly name the intended subject within the request.  These
   artefacts have been defined to permit application in scenarios other
   than ABFAB, such as network access.

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 August 29, 2013.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.



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   This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents

   1.  TODO . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   4.  RADIUS SAML-Message Attribute  . . . . . . . . . . . . . . . .  6
   5.  SAML RADIUS Binding  . . . . . . . . . . . . . . . . . . . . .  7
     5.1.  Required Information . . . . . . . . . . . . . . . . . . .  7
     5.2.  Operation  . . . . . . . . . . . . . . . . . . . . . . . .  7
       5.2.1.  Use of XML Signatures  . . . . . . . . . . . . . . . .  8
       5.2.2.  Metadata Considerations  . . . . . . . . . . . . . . .  8
   6.  Network Access Identifier Name Identifier Format . . . . . . .  8
   7.  ABFAB Authentication Profile . . . . . . . . . . . . . . . . .  8
     7.1.  Required Information . . . . . . . . . . . . . . . . . . .  9
     7.2.  Profile Overview . . . . . . . . . . . . . . . . . . . . .  9
     7.3.  Profile Description  . . . . . . . . . . . . . . . . . . . 11
       7.3.1.  User Agent Request to Relying Party  . . . . . . . . . 11
       7.3.2.  Relying Party Issues <samlp:AuthnRequest> to
               Identity Provider  . . . . . . . . . . . . . . . . . . 11
       7.3.3.  Identity Provider Identifies Principal . . . . . . . . 11
       7.3.4.  Identity Provider Issues <samlp:Response> to
               Relying Party  . . . . . . . . . . . . . . . . . . . . 12
       7.3.5.  Relying Party Grants or Denies Access to Principal . . 12
     7.4.  Use of Authentication Request Protocol . . . . . . . . . . 12
       7.4.1.  <samlp:AuthnRequest> Usage . . . . . . . . . . . . . . 12
       7.4.2.  <samlp:Response message> Usage . . . . . . . . . . . . 13
       7.4.3.  samlp:Response Message Processing Rules  . . . . . . . 13
       7.4.4.  Unsolicited Responses  . . . . . . . . . . . . . . . . 14
       7.4.5.  Use of the SAML RADIUS Binding . . . . . . . . . . . . 14
       7.4.6.  Use of XML Signatures  . . . . . . . . . . . . . . . . 14
       7.4.7.  Metadata Considerations  . . . . . . . . . . . . . . . 14
   8.  ABFAB Assertion Query/Request Profile  . . . . . . . . . . . . 14
     8.1.  Required Information . . . . . . . . . . . . . . . . . . . 15
     8.2.  Profile Overview . . . . . . . . . . . . . . . . . . . . . 15
     8.3.  Profile Description  . . . . . . . . . . . . . . . . . . . 16
       8.3.1.  Differences from the SAML V2.0 Assertion
               Query/Request Profile  . . . . . . . . . . . . . . . . 16
       8.3.2.  Use of the SAML RADIUS Binding . . . . . . . . . . . . 16
       8.3.3.  Use of XML Signatures  . . . . . . . . . . . . . . . . 16
       8.3.4.  Metadata Considerations  . . . . . . . . . . . . . . . 16
   9.  RADIUS State Confirmation Methods  . . . . . . . . . . . . . . 16
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
   11. Security Considerations  . . . . . . . . . . . . . . . . . . . 17
   12. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 17
     12.1. RADIUS Attributes  . . . . . . . . . . . . . . . . . . . . 17
     12.2. ABFAB Parameters . . . . . . . . . . . . . . . . . . . . . 17
     12.3. Registration of the ABFAB URN Namespace  . . . . . . . . . 18
   13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18



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     13.1. Normative References . . . . . . . . . . . . . . . . . . . 18
     13.2. Informative References . . . . . . . . . . . . . . . . . . 19

















































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1.  TODO

   o  What NAI do we use in Access-Requests for Assertion Query/
      Requests?  Possibly define well-known user@realm value for AA,
      etc?  We probably also need a way to map NAI names to entityIDs.

   o  Clean up use of terminology (e.g., "principal") to ensure
      consistency with other ABFAB docs.

2.  Introduction

   The SAML RADIUS attribute, binding, profiles, name identifier format
   and confirmation methods are motivated by the requirements of the
   ABFAB architecture [I-D.ietf-abfab-arch].  In this architecture, it
   is often desirable to convey Security Assertion Mark-up Language
   (SAML) protocol messages between a SAML requester and SAML responder.
   This can be used, for example, to allow a Relying Party to request a
   SAML assertion from an Identity Provider that describes a particular
   principal.

   SAML typically only considers the of use HTTP-based transports, known
   as bindings [OASIS.saml-bindings-2.0-os], which are primarily
   intended for use with the SAML V2.0 Web Browser Single Sign-On
   Profile [OASIS.saml-profiles-2.0-os].  However the goal of ABFAB is
   to extend the applicability of federated identity beyond the Web to
   other applications by building on the AAA framework.  Consequently
   there exists a requirement for SAML to integrate with the AAA
   framework and protocols such as RADIUS [RFC2865] and Diameter
   [RFC3588], in addition to HTTP.

   A companion specification [I-D.jones-diameter-abfab] specifies
   equivalent funtionality for Diameter.

   In summary this document specifies:

   o  A SAML RADIUS attribute that defines how to encapsulate a SAML
      protocol message within a RADIUS attribute.

   o  A SAML RADIUS binding that defines how SAML requesters and
      responders can exchange SAML protocol messages.

   o  An Authentication Profile that defines how the SAML RADIUS binding
      is used to effect SAML-based authentication and authorization.

   o  An Assertion Query/Request Profile that defines how the SAML
      RADIUS binding is used to effect SAML-based assertion request.





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   o  Two subject confirmation methods for indicating that a user or
      machine principal respectively is the subject of an assertion.

   This document aspires to the guidelines stipulated by
   [OASIS.saml-bindings-2.0-os] and [OASIS.saml-profiles-2.0-os] for
   defining new SAML bindings and profiles respectively, and other
   conventions applied formally or otherwise within SAML.  In particular
   where this document provides a 'Required Information' section for the
   binding and profiles that enumerate:

   o  A URI that uniquely identifies the protocol binding or profile

   o  Postal or electronic contact information for the author

   o  A reference to previously defined bindings or profiles that the
      new binding updates or obsoletes

   o  In the case of a profile, any SAML confirmation method identifiers
      defined and/or utilized by the profile

3.  Conventions

   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 [RFC2119].

4.  RADIUS SAML-Message Attribute

   This attribute contains a SAML [OASIS.saml-core-2.0-os] protocol
   message.  Where multiple SAML-Message attributes are included in a
   RADIUS message, the Message fields of these attributes are to be
   concatenated to form a single SAML message.

   A summary of the SAML-Message format is shown below.  The fields are
   transmitted from left to right.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |         SAML Message...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                    Figure 1








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   Type:  TBD

   Length:  >=3

   Message:  The Message field is one or more octets containing a SAML
      message.  If larger than a single attribute, the SAML message data
      MUST be split on 253-octet boundaries over as many attributes as
      necessary.  The SAML message is reconstructed by concatenating the
      contents of all SAML-Message attributes.

5.  SAML RADIUS Binding

   The SAML RADIUS binding defines how RADIUS [RFC2865] can be used to
   enable a RADIUS client and server to exchange SAML protocol messages.

5.1.  Required Information

   Identification: urn:ietf:params:abfab:bindings:radius

   Contact information: iesg@ietf.org

   Updates: None.

5.2.  Operation

   RADIUS can be used over multiple underlying transports; this binding
   calls out the use of Transport Layer Security (TLS) Encryption for
   RADIUS as REQUIRED [I-D.ietf-radext-radsec] to provide
   confidentiality, improve integrity protection and support the use of
   longer SAML messages.

   Implementations of this profile MAY use RADIUS packet fragmentation
   [I-D.perez-radext-radius-fragmentation] to permit transport of longer
   SAML messages over RADIUS UDP transport.

   The system model used for SAML conversations over RADIUS is a simple
   request-response model, using the RADIUS SAML-Message attribute
   defined in Section 4 to encapsulate the SAML protocol messages.

   1.  The RADIUS client, acting as a SAML requester, MAY transmit a
       SAML request element within a RADIUS Access-Request message.
       This message MUST include a single instance of the RADIUS User-
       Name attribute whose value MUST conform to the Network Access
       Identifier [RFC4282] scheme.  The SAML requester MUST NOT include
       more than one SAML request element.

   2.  The RADIUS server, acting as a SAML responder, MAY return a SAML
       protocol message within a RADIUS Access-Accept or Access-Reject



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       message.  These messages necessarily conclude a RADIUS exchange
       and therefore this is the only opportunity for the SAML responder
       to send a response in the context of this exchange.  The SAML
       responder MUST NOT include more than one SAML response.  A SAML
       responder that refuses to perform a message exchange with the
       SAML requester MUST silently discard the SAML request.

   A SAML responder MAY also return an unsolicited response (a SAML
   response generated and emitted in the absence of a request from a
   SAML requester).

   This binding is intended to be composed with other uses of RADIUS,
   such as network access.  Therefore, other arbitrary RADIUS attributes
   MAY be used in either the request or response.

   In the case of a SAML processing error and successful authentication,
   the RADIUS server SHOULD include a SAML-specified <samlp:Status>
   element in the SAML response that is transported within the Access-
   Accept packet sent by the RADIUS server.

   In the case of a SAML processing error and failed authentication, the
   RADIUS server MAY include a SAML-specified <samlp:Status> element in
   the SAML response that is transported within the Access-Reject packet
   sent by the RADIUS server.

5.2.1.  Use of XML Signatures

   This bindings calls for the use of SAML elements that support XML
   signatures.  To promote interoperability implementations of this
   binding MUST NOT require the use of XML signatures.  Implementations
   MAY choose to use XML signatures, but this usage is outside of the
   scope of this binding.

5.2.2.  Metadata Considerations

   There are no metadata considerations particular to this binding.

6.  Network Access Identifier Name Identifier Format

   URI: urn:ietf:params:abfab:nameid-format:nai

   Indicates that the content of the element is in the form of a Network
   Access Identifier (NAI) using the syntax described by [RFC4282].

7.  ABFAB Authentication Profile

   In the scenario supported by the ABFAB Authentication Profile, a
   Principal controlling a User Agent requests access to a Relying



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   Party.  The User Agent and Relying Party uses EAP to authenticate the
   Principal.  The Relying Party, acting as an EAP pass-through
   authenticator, acts as a conduit for the EAP frames emitted by the
   User Agent and an EAP server which acts as the Principal's Identity
   Provider.  If the Identity Provider successfully authenticates the
   Principal, it produces an authentication assertion which is consumed
   by the Relying Party.  During this process, a name identifier might
   also be established between the Relying Party and the Identity
   Provider.

7.1.  Required Information

   Identification: urn:ietf:params:abfab:profiles:authentication

   Contact information: iesg@ietf.org

   SAML Confirmation Method Identifiers: The SAML V2.0 "sender vouches"
   confirmation method identifier,
   urn:oasis:names:tc:SAML:2.0:cm:sender-vouches, is used by this
   profile.

   Updates: None.

7.2.  Profile Overview

   To implement this scenario a profile of the SAML Authentication
   Request protocol is used in conjuction with the SAML RADIUS binding
   defined in Section 5, and EAP.

   This profile is based on the SAML V2.0 Web Browser Single Sign-On
   Profile [OASIS.saml-profiles-2.0-os].  There are some important
   differences, specifically:

   Authentication:  This profile requires the use of EAP, although not a
      particular EAP authentication method.  This allows the use of a
      variety of different EAP authentication mechanisms.

   Bindings:  This profile does not require the use of HTTP-based
      bindings.  Instead all SAML protocol messages are transported
      using the SAML RADIUS binding defined in Section 5.  This is
      intended to reduce the number of bindings that implementations
      must support to be interoperable.

   Requests:  The profile does not permit the Relying Party to name the
      <saml:Subject> of the <samlp:AuthnRequest>.  This is intended to
      simplify implementation and interoperability.





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   Responses:  The profile only permits the Identity Provider to return
      a single assertion that must contain exactly one authentication
      statement.  Other statements may be included within this assertion
      at the discretion of the Identity Provider.  This is intended to
      simplify implementation and interoperability.

   Figure 1 below illustrates the flow of messages within this profile.

     User Agent          Relying Party             Identity Provider
         |                     |                           |
         |         (1)         |                           |
         | - - - - - - - - - > |                           |
         |                     |                           |
         |                     |            (2)            |
         |                     | - - - - - - - - - - - - > |
         |                     |                           |
         |              (3)    |                           |
         | < - - - - - - - - - |- - - - - - - - - - - - -> |
         |                     |                           |
         |                     |            (4)            |
         |                     | < - - - - - - - - - - - - |
         |                     |                           |
         |         (5)         |                           |
         | < - - - - - - - - - |                           |
         |                     |                           |
         V                     V                           V

   The following steps are described by the profile.  Within an
   individual step, there may be one or more actual message exchanges.

                                 Figure 1

   1.  User Agent Request to Relying Party (Section 7.3.1): In step 1,
       the Principal, via a User Agent, makes a request for a secured
       resource at the Relying Party.  The Relying Party determines that
       no security context for the User Agent exists and initiates EAP
       authentication of the Principal.

   2.  Relying Party Issues <samlp:AuthnRequest> to Identity Provider
       (Section 7.3.2).  In step 2, the Relying Party may optionally
       issue a <samlp:AuthnRequest> message to be delivered to the
       Identity Provider using the SAML RADIUS binding.

   3.  Identity Provider Identifies Principal (Section 7.3.3).  In step
       3, the Principal is identified by the Identity Provider using EAP
       authentication, while honoring any requirements imposed by the
       Relying Party in the <samlp:AuthnRequest> message if provided.




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   4.  Identity Provider Issues <samlp:Response> to Relying Party
       (Section 7.3.4).  In step 4, the Identity Provider issues a
       <samlp:Response> message to the Relying Party using the SAML
       RADIUS binding.  The response either indicates an error or
       includes an authentication statement in exactly one assertion.

   5.  Relying Party Grants or Denies Access to Principal
       (Section 7.3.5).  In step 5, having received the response from
       the Identity Provider, the Relying Party can respond to the
       Principal's User Agent with its own error, or can establish its
       own security context for the Principal and return the requested
       resource.

7.3.  Profile Description

   The ABFAB Authentication Profile is a profile of the SAML V2.0
   Authentication Request Protocol [OASIS.saml-core-2.0-os].  Where this
   specification conflicts with Core, the former takes precedence.

7.3.1.  User Agent Request to Relying Party

   The profile is initiated by an arbitrary User Agent request to the
   Relying Party.  There are no restrictions on the form of the request.
   The Relying Party is free to use any means it wishes to associate the
   subsequent interactions with the original request.  The Relying
   Party, acting as an EAP authenticator, sends an EAP-Identity/Request
   message to the User Agent, acting as an EAP peer.

7.3.2.  Relying Party Issues <samlp:AuthnRequest> to Identity Provider

   The Relying Party, on receiving the EAP-Identity/Response message
   from the User Agent, MUST send it towards the Identity Provider using
   RADIUS as described in [RFC3579].  The Relying Party MAY include a
   <samlp:AuthnRequest> within this RADIUS Access-Request message using
   the SAML RADIUS binding.  The next hop destination MAY be the
   Identity Provider or alternatively an intermediate RADIUS proxy.

   Profile-specific rules for the contents of the <samlp:AuthnRequest>
   element are given in Section 7.4.1.

7.3.3.  Identity Provider Identifies Principal

   The Identity Provider MUST establish the identity of the Principal
   using EAP authentication, or else it will return an error.  If the
   ForceAuthn attribute on the <samlp:AuthnRequest> element (if sent by
   the requester) is present and true, the Identity Provider MUST
   freshly establish this identity rather than relying on any existing
   session state it may have with the Principal (for example, TLS state



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   that may be used for session resumption).  Otherwise, and in all
   other respects, the Identity Provider may use any EAP method to
   authenticate the Principal, subject to the requirements of Section
   5.8 of [I-D.ietf-abfab-gss-eap] and any others called out in the
   <samlp:AuthnRequest> message.

7.3.4.  Identity Provider Issues <samlp:Response> to Relying Party

   The Identity Provider MUST conclude the EAP authentication in a
   manner consistent with the EAP authentication result, and MAY issue a
   <samlp:Response> message to the Relying Party consisent with the
   authentication result and as described in [OASIS.saml-core-2.0-os]
   and delivered to the Relying Party using the SAML RADIUS binding.

   Profile-specific rules regarding the contents of the <samlp:Response>
   element are given in Section 7.4.2.

7.3.5.  Relying Party Grants or Denies Access to Principal

   If issued by the Identity Provider, the Relying Party MUST process
   the <samlp:Response> message and any enclosed <saml:Assertion>
   elements as described in [OASIS.saml-core-2.0-os].  Any subsequent
   use of the <saml:Assertion> elements is at the discretion of the
   Relying Party, subject to any restrictions on use contained within
   the assertions themselves or previously established out-of-band
   policy governing interactions between the Identity Provider and the
   Relying Party.

7.4.  Use of Authentication Request Protocol

   This profile is based on the Authentication Request Protocol defined
   in [OASIS.saml-core-2.0-os].  In the nomenclature of actors
   enumerated in section 3.4, the Relying Party is the requester, the
   User Agent is the attesting entity and the Principal is the Requested
   Subject.

7.4.1.  <samlp:AuthnRequest> Usage

   A Relying Party MAY include any message content described in
   [OASIS.saml-core-2.0-os], section 3.4.1.  All processing rules are as
   defined in [OASIS.saml-core-2.0-os].

   If the Identity Provider cannot or will not satisfy the request, it
   MAY respond with a <samlp:Response> message containing an appropriate
   error status code or codes.

   If the Relying Party wishes to permit the Identity Provider to
   establish a new identifier for the principal if none exists, it MUST



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   include a <saml:NameIDPolicy> element with the AllowCreate attribute
   set to "true".  Otherwise, only a principal for whom the Identity
   Provider has previously established an identifier usable by the
   Relying Party can be authenticated successfully.

   The Relying Party MUST NOT include a <saml:Subject> element in the
   request.  The authenticated EAP Identity names the Principal of the
   requested <samlp:AuthnRequest> to the Identity Provider.

   The <samlp:AuthnRequest> message MAY be signed.  Authentication and
   integrity are also provided by the RADIUS SAML binding.

7.4.2.  <samlp:Response message> Usage

   If the Identity Provider wishes to return an error, it MUST NOT
   include any assertions in the <samlp:Response message>.  Otherwise,
   if the request is successful (or if the response is not associated
   with a request), the <samlp:Response> element MUST conform to the
   following:

   o  It MAY be signed.

   o  It MUST contain exactly one <saml:Assertion>.  The <saml:Subject>
      element of this assertion MUST refer to the authenticated
      Principal.

   o  The assertion MUST contain a <saml:AuthnStatement>.  This MUST
      contain a <saml:Subject> element with at least one <saml:
      SubjectConfirmation> element containing a Method of
      urn:oasis:names:tc:SAML:2.0:cm:sender-vouches that reflects the
      authentication of the Principal to the Identity Provider.  If the
      containing message is in response to an <samlp:AuthnRequest>, then
      the InResponseTo attribute MUST match the request's ID.

   o  Other conditions MAY be included as requested by the Relying Party
      or at the discretion of the Identity Provider.  The Identity
      Provider is NOT obligated to honor the requested set of conditions
      in the <samlp:AuthnRequest>, if any.

7.4.3.  samlp:Response Message Processing Rules

   The Relying Party MUST do the following:

   o  Verify that the InResponseTo attribute in the sender-vouches
      <saml:SubjectConfirmationData> equals the ID of its original
      <samlp:AuthnRequest> message, unless the response is unsolicited,
      in which case the attribute MUST NOT be present.




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   o  If a <saml:AuthnStatement> used to establish a security context
      for the Principal contains a SessionNotOnOrAfter attribute, the
      security context SHOULD be discarded once this time is reached,
      unless the service provider reestablishes the Principal's identity
      by repeating the use of this profile.

   o  Verify that any assertions relied upon are valid according to
      processing rules in [OASIS.saml-core-2.0-os].

   o  Any assertion which is not valid, or whose subject confirmation
      requirements cannot be met MUST be discarded and MUST NOT be used
      to establish a security context for the Principal.

7.4.4.  Unsolicited Responses

   An Identity Provider MAY initiate this profile by delivering an
   unsolicited <samlp:Response> message to a Relying Party.

   An unsolicited <samlp:Response> MUST NOT contain an InResponseTo
   attribute, nor should any sender-vouches <saml:
   SubjectConfirmationData> elements contain one.

7.4.5.  Use of the SAML RADIUS Binding

   It is RECOMMENDED that the RADIUS exchange is protected using TLS
   encryption for RADIUS [I-D.ietf-radext-radsec] to provide
   confidentiality and improve integrity protection.

7.4.6.  Use of XML Signatures

   This profile calls for the use of SAML elements that support XML
   signatures.  To promote interoperability implementations of this
   profile MUST NOT require the use of XML signatures.  Implementations
   MAY choose to use XML signatures, but this usage is outside of the
   scope of this profile.

7.4.7.  Metadata Considerations

   There are no metadata considerations particular to this binding.

8.  ABFAB Assertion Query/Request Profile

   This profile builds on the SAML V2.0 Assertion Query/Request Profile
   defined by [OASIS.saml-profiles-2.0-os].  That profile describes the
   use of the Assertion Query and Request Protocol defined by section
   3.3 of [OASIS.saml-core-2.0-os] with synchronous bindings, such as
   the SOAP binding defined in [OASIS.saml-bindings-2.0-os] or the SAML
   RADIUS binding defined elsewhere in this document.



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   While the SAML V2.0 Assertion Query/Request Profile is independent of
   the underlying binding, it is nonetheless useful to describe the use
   of this profile with the SAML RADIUS binding in the interests of
   promoting interoperable implementations, particularly as the SAML
   V2.0 Assertion Query/Request Profile is most frequently discussed and
   implemented in the context of the SOAP binding.

8.1.  Required Information

   Identification: urn:ietf:params:abfab:profiles:query

   Contact information: iesg@ietf.org

   Description: Given below.

   Updates: None.

8.2.  Profile Overview

   As with the SAML V2.0 Assertion Query/Request Profile defined by
   [OASIS.saml-profiles-2.0-os] the message exchange and basic
   processing rules that govern this profile are largely defined by
   Section 3.3 of [OASIS.saml-core-2.0-os] that defines the messages to
   be exchanged, in combination with the binding used to exchange the
   messages.  The SAML RADIUS binding described in this document defines
   the binding of the message exchange to RADIUS.  Unless specifically
   noted here, all requirements defined in those specifications apply.

   Figure 2 below illustrates the basic template for the query/request
   profile.

     SAML Requester                                  SAML Authority
         |                                                 |
         |                       (1)                       |
         | - - - - - - - - - - - - - - - - - - - - - - - > |
         |                                                 |
         |                       (2)                       |
         | < - - - - - - - - - - - - - - - - - - - - - - - |
         |                                                 |
         |                                                 |
         V                                                 V

   The following steps are described by the profile.

                                 Figure 2






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   1.  Query/Request issued by SAML Requester: In step 1, a SAML
       requester initiates the profile by sending an
       <AssertionIDRequest>, <SubjectQuery>, <AuthnQuery>,
       <AttributeQuery>, or <AuthzDecisionQuery> message to a SAML
       authority.

   2.  <Response> issued by SAML Authority: In step 2, the responding
       SAML authority (after processing the query or request) issues a
       <Response> message to the SAML requester.

8.3.  Profile Description

8.3.1.  Differences from the SAML V2.0 Assertion Query/Request Profile

   This profile is identical to the SAML V2.0 Assertion Query/Request
   Profile, with the following exceptions:

   o  In respect to section 6.3.1 and 6.5, this profile does not
      consider the use of metadata (as in [OASIS.saml-metadata-2.0-os]);
      see Section 8.3.4.

   o  In respect to sections 6.3.2, 6.4.1 and 6.4.2, this profile
      additionally stipulates that implementations of this profile MUST
      NOT require the use of XML signatures; see Section 8.3.3.

8.3.2.  Use of the SAML RADIUS Binding

   It is RECOMMENDED that the RADIUS exchange is protected using TLS
   encryption for RADIUS [I-D.ietf-radext-radsec] to provide
   confidentiality and improve integrity protection.

8.3.3.  Use of XML Signatures

   This profile calls for the use of SAML elements that support XML
   signatures.  To promote interoperability implementations of this
   profile MUST NOT require the use of XML signatures.  Implementations
   MAY choose to use XML signatures, but this usage is outside of the
   scope of this profile.

8.3.4.  Metadata Considerations

   There are no metadata considerations particular to this binding.

9.  RADIUS State Confirmation Methods

   URI: urn:ietf:params:abfab:cm:user

   URI: urn:ietf:params:abfab:cm:machine



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   The RADIUS State Confirmation Methods indicate that the Subject is
   the system entity (either the user or machine) authenticated by a
   previously transmitted RADIUS Access-Accept message, as identified by
   the value of that RADIUS message's State attribute.

10.  Acknowledgements

   TODO: Need to acknowledge OASIS SSTC, UoMurcia, Scott and Steven.

11.  Security Considerations

   TODO

12.  IANA Considerations

12.1.  RADIUS Attributes

   Assignments of additional enumerated values for the RADIUS attribute
   defined in this document are to be processed as described in
   [RFC3575], subject to the additional requirements of a published
   specification.

12.2.  ABFAB Parameters

   A new top-level registry is created titled "ABFAB Parameters".

   In this top-level registry, a sub-registry titled "ABFAB URN
   Parameters" is created.  Registration in this registry is by the IETF
   review or expert review procedures [RFC5226].

   This paragraph gives guidance to designated experts.  Registrations
   in this registry are generally only expected as part of protocols
   published as RFCs on the IETF stream; other URIs are expected to be
   better choices for non-IETF work.  Expert review is permitted mainly
   to permit early registration related to specifications under
   development when the community believes they have reach sufficient
   maturity.  The expert SHOULD evaluate the maturity and stability of
   such an IETF-stream specification.  Experts SHOULD review anything
   not from the IETF stream for consistency and consensus with current
   practice.  Today such requests would not typically be approved.

   If the "paramname" parameter is registered in this registry then its
   URN will be "urn:ietf:params:abfab:paramname".  The initial
   registrations are as follows:







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                  +-------------------------+-----------+
                  | Parameter               | Reference |
                  +-------------------------+-----------+
                  | bindings:radius         | Section 5 |
                  | nameid-format:nai       | Section 6 |
                  | profiles:authentication | Section 7 |
                  | profiles:query          | Section 8 |
                  | cm:user                 | Section 9 |
                  | cm:machine              | Section 9 |
                  +-------------------------+-----------+

                             ABFAB Parameters

12.3.  Registration of the ABFAB URN Namespace

   IANA is requested to register the "abfab" URN sub-namespace in the
   IETF URN sub-namespace for protocol parameters defined in [RFC3553].

   Registry Name: abfab

   Specification: draft-ietf-abfab-aaa-saml

   Repository: ABFAB URN Parameters (Section Section 12.2)

   Index Value: Sub-parameters MUST be specified in UTF-8 using standard
   URI encoding where necessary.

13.  References

13.1.  Normative References

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

   [I-D.ietf-radext-radsec]                 Winter, S., McCauley, M.,
                                            Venaas, S., and K. Wierenga,
                                            "TLS encryption for RADIUS",
                                            draft-ietf-radext-radsec-09
                                            (work in progress),
                                            July 2011.

   [I-D.ietf-abfab-gss-eap]                 Howlett, J. and S. Hartman,
                                            "A GSS-API Mechanism for the
                                            Extensible Authentication
                                            Protocol",
                                            draft-ietf-abfab-gss-eap-04



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                                            (work in progress),
                                            October 2011.

   [I-D.perez-radext-radius-fragmentation]  Perez-Mendez, A., Lopez, R.,
                                            Pereniguez-Garcia, F.,
                                            Lopez-Millan, G., Lopez, D.,
                                            and A. DeKok, "Support of
                                            fragmentation of RADIUS
                                            packets", draft-perez-
                                            radext-radius-fragmentation-
                                            01 (work in progress),
                                            February 2012.

13.2.  Informative References

   [RFC2865]                                Rigney, C., Willens, S.,
                                            Rubens, A., and W. Simpson,
                                            "Remote Authentication Dial
                                            In User Service (RADIUS)",
                                            RFC 2865, June 2000.

   [RFC3553]                                Mealling, M., Masinter, L.,
                                            Hardie, T., and G. Klyne,
                                            "An IETF URN Sub-namespace
                                            for Registered Protocol
                                            Parameters", BCP 73,
                                            RFC 3553, June 2003.

   [RFC3575]                                Aboba, B., "IANA
                                            Considerations for RADIUS
                                            (Remote Authentication Dial
                                            In User Service)", RFC 3575,
                                            July 2003.

   [RFC3579]                                Aboba, B. and P. Calhoun,
                                            "RADIUS (Remote
                                            Authentication Dial In User
                                            Service) Support For
                                            Extensible Authentication
                                            Protocol (EAP)", RFC 3579,
                                            September 2003.

   [RFC3588]                                Calhoun, P., Loughney, J.,
                                            Guttman, E., Zorn, G., and
                                            J. Arkko, "Diameter Base
                                            Protocol", RFC 3588,
                                            September 2003.




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   [RFC4282]                                Aboba, B., Beadles, M.,
                                            Arkko, J., and P. Eronen,
                                            "The Network Access
                                            Identifier", RFC 4282,
                                            December 2005.

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

   [I-D.jones-diameter-abfab]               Jones, M. and H. Tschofenig,
                                            "The Diameter 'Application
                                            Bridging for Federated
                                            Access Beyond Web (ABFAB)'
                                            Application", draft-jones-
                                            diameter-abfab-00 (work in
                                            progress), March 2011.

   [I-D.ietf-abfab-arch]                    Howlett, J., Hartman, S.,
                                            Tschofenig, H., Lear, E.,
                                            and J. Schaad, "Application
                                            Bridging for Federated
                                            Access Beyond Web (ABFAB)
                                            Architecture",
                                            draft-ietf-abfab-arch-03
                                            (work in progress),
                                            July 2012.

   [OASIS.saml-bindings-2.0-os]             Cantor, S., Hirsch, F.,
                                            Kemp, J., Philpott, R., and
                                            E. Maler, "Bindings for the
                                            OASIS Security Assertion
                                            Markup Language (SAML)
                                            V2.0", OASIS Standard saml-
                                            bindings-2.0-os, March 2005.

   [OASIS.saml-core-2.0-os]                 Cantor, S., Kemp, J.,
                                            Philpott, R., and E. Maler,
                                            "Assertions and Protocol for
                                            the OASIS Security Assertion
                                            Markup Language (SAML)
                                            V2.0", OASIS Standard saml-
                                            core-2.0-os, March 2005.

   [OASIS.saml-profiles-2.0-os]             Hughes, J., Cantor, S.,



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                                            Hodges, J., Hirsch, F.,
                                            Mishra, P., Philpott, R.,
                                            and E. Maler, "Profiles for
                                            the OASIS Security Assertion
                                            Markup Language (SAML)
                                            V2.0", OASIS Standard OASIS.
                                            saml-profiles-2.0-os,
                                            March 2005.

   [OASIS.saml-metadata-2.0-os]             Cantor, S., Moreh, J.,
                                            Philpott, R., and E. Maler,
                                            "Metadata for the Security
                                            Assertion Markup Language
                                            (SAML) V2.0", OASIS Standard
                                             saml-metadata-2.0-os,
                                            March 2005.

Authors' Addresses

   Josh Howlett
   Janet
   Lumen House, Library Avenue, Harwell
   Oxford  OX11 0SG
   UK

   Phone: +44 1235 822363
   EMail: Josh.Howlett@ja.net


   Sam Hartman
   Painless Security


   Phone:
   EMail: hartmans-ietf@mit.edu
















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