[Docs] [txt|pdf|xml] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 RFC 7833

ABFAB                                                         J. Howlett
Internet-Draft                                                     Janet
Intended status: Informational                                S. Hartman
Expires: April 21, 2013                                Painless Security
                                                        October 18, 2012


           A RADIUS Attribute, Binding and Profiles for SAML
                      draft-ietf-abfab-aaa-saml-04

Abstract

   This document specifies a RADIUS attribute, a binding and two
   profiles 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 SAML RADIUS attribute and
   binding are defined generically to permit application in other
   scenarios, 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 April 21, 2013.

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



Howlett & Hartman        Expires April 21, 2013                 [Page 1]


Internet-Draft                 SAML RADIUS                  October 2012


   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.  TODO . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  RADIUS SAML-Message Attribute  . . . . . . . . . . . . . . . .  5
   5.  SAML RADIUS Binding  . . . . . . . . . . . . . . . . . . . . .  6
     5.1.  Required Information . . . . . . . . . . . . . . . . . . .  6
     5.2.  Operation  . . . . . . . . . . . . . . . . . . . . . . . .  6
       5.2.1.  Use of XML Signatures  . . . . . . . . . . . . . . . .  7
       5.2.2.  Metadata Considerations  . . . . . . . . . . . . . . .  8
   6.  ABFAB Authentication Profile . . . . . . . . . . . . . . . . .  8
     6.1.  Required Information . . . . . . . . . . . . . . . . . . .  8
     6.2.  Profile Overview . . . . . . . . . . . . . . . . . . . . .  8
     6.3.  Profile Description  . . . . . . . . . . . . . . . . . . . 10
       6.3.1.  User Agent Request to Relying Party  . . . . . . . . . 10
       6.3.2.  Relying Party Issues <samlp:AuthnRequest> to
               Identity Provider  . . . . . . . . . . . . . . . . . . 10
       6.3.3.  Identity Provider Identifies Principal . . . . . . . . 11
       6.3.4.  Identity Provider Issues <samlp:Response> to
               Relying Party  . . . . . . . . . . . . . . . . . . . . 11
       6.3.5.  Relying Party Grants or Denies Access to Principal . . 11
     6.4.  Use of Authentication Request Protocol . . . . . . . . . . 11
       6.4.1.  <samlp:AuthnRequest> Usage . . . . . . . . . . . . . . 12
       6.4.2.  <samlp:Response message> Usage . . . . . . . . . . . . 12
       6.4.3.  samlp:Response Message Processing Rules  . . . . . . . 13
       6.4.4.  Unsolicited Responses  . . . . . . . . . . . . . . . . 13
       6.4.5.  Use of the SAML RADIUS Binding . . . . . . . . . . . . 13
       6.4.6.  Use of XML Signatures  . . . . . . . . . . . . . . . . 13
       6.4.7.  Metadata Considerations  . . . . . . . . . . . . . . . 14
   7.  ABFAB Assertion Query/Request Profile  . . . . . . . . . . . . 14
     7.1.  Required Information . . . . . . . . . . . . . . . . . . . 14
     7.2.  Profile Overview . . . . . . . . . . . . . . . . . . . . . 14
     7.3.  Profile Description  . . . . . . . . . . . . . . . . . . . 15
       7.3.1.  Differences from the SAML V2.0 Assertion
               Query/Request Profile  . . . . . . . . . . . . . . . . 15
       7.3.2.  Use of the SAML RADIUS Binding . . . . . . . . . . . . 15
       7.3.3.  Use of XML Signatures  . . . . . . . . . . . . . . . . 16
       7.3.4.  Metadata Considerations  . . . . . . . . . . . . . . . 16
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 16



Howlett & Hartman        Expires April 21, 2013                 [Page 2]


Internet-Draft                 SAML RADIUS                  October 2012


   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 16
     11.2. Informative References . . . . . . . . . . . . . . . . . . 17
















































Howlett & Hartman        Expires April 21, 2013                 [Page 3]


Internet-Draft                 SAML RADIUS                  October 2012


1.  TODO

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

   o  Understand Alan DeK's preferences with respect to choreography of
      SAML messages and the RADIUS exchange(s).

   o  Request a new RADIUS attribute

   o  Check that binding/profiles identification URNs are reasonable

2.  Introduction

   The SAML RADIUS attribute, binding and profiles 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.  This attribute and binding
   are also likely to be useful for other purposes besides ABFAB; for
   example, SAML-based authorization for network access.  The attribute
   and binding are therefore defined generically to facilitate general
   applicability.

   SAML defines a number of SAML protocol messages
   [OASIS.saml-core-2.0-os], derived from common request and response
   abstract types.  These request and response protocol messages can be
   exchanged using different modes of transport, such as HTTP; in the
   SAML architecture, these are known as 'bindings'.  SAML already
   defines a number of HTTP-based bindings [OASIS.saml-bindings-2.0-os];
   and these are primarily intended for use with the SAML V2.0 Web
   Browser Single Sign-On Profile [OASIS.saml-profiles-2.0-os] which
   describes how the SAML protocol messages and HTTP-based bindings can
   be used to effect Web-based Single Sign-On (SSO) by federating an
   identity between an Identity Provider and a Service Provider

   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 an AAA-based
   binding that is functionally equivalent to the existing bindings but
   using AAA protocols, such as [RFC2865] and Diameter [RFC3588], rather
   than HTTP.  This document therefore defines a new RADIUS-based SAML
   binding, building on a SAML RADIUS attribute also defined by this
   document, to meet this need.

   In addition to this attribute and binding, this document also



Howlett & Hartman        Expires April 21, 2013                 [Page 4]


Internet-Draft                 SAML RADIUS                  October 2012


   profiles their application in the context of two specific use cases:
   authentication and assertion query/request.  This is intended to
   promote interoperability between implementations for these common use
   cases.

   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.

   The RADIUS SAML binding and profile specifications aspire to adhere
   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.  These new bindings and profiles are asked to
   provide a 'Required Information' section that enumerates:

   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



Howlett & Hartman        Expires April 21, 2013                 [Page 5]


Internet-Draft                 SAML RADIUS                  October 2012


   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

   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:xml:ns: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 RADIUS over UDP as REQUIRED.  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.  Implementations of this profile MUST support
   RADIUS packet fragmentation [I-D.perez-radext-radius-fragmentation]
   to permit transport of large SAML messages.

   The system model used for SAML conversations over RADIUS is a simple



Howlett & Hartman        Expires April 21, 2013                 [Page 6]


Internet-Draft                 SAML RADIUS                  October 2012


   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
       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.







Howlett & Hartman        Expires April 21, 2013                 [Page 7]


Internet-Draft                 SAML RADIUS                  October 2012


5.2.2.  Metadata Considerations

   There are no metadata considerations particular to this binding.

6.  ABFAB Authentication Profile

   In the scenario supported by the ABFAB Authentication Profile, a
   Principal controlling a User Agent requests access to a Relying
   Party.  The User Agent and Relying Party use the GSS EAP mechanism 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.

6.1.  Required Information

   Identification: urn:ietf:params:xml:ns: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.

6.2.  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 the GSS EAP mechanism
   [I-D.ietf-abfab-gss-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 a particular
      authentication framework (namely the GSS EAP mechanism), although
      not a particular EAP authentication method.  This allows the
      profile to build on the EAP, AAA and GSS frameworks that comprise
      the core of the ABFAB architecture.




Howlett & Hartman        Expires April 21, 2013                 [Page 8]


Internet-Draft                 SAML RADIUS                  October 2012


   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.

   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 6.3.1): 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 GSS
       EAP authentication of the Principal.




Howlett & Hartman        Expires April 21, 2013                 [Page 9]


Internet-Draft                 SAML RADIUS                  October 2012


   2.  Relying Party Issues <samlp:AuthnRequest> to Identity Provider
       (Section 6.3.2).  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 6.3.3).  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.

   4.  Identity Provider Issues <samlp:Response> to Relying Party
       (Section 6.3.4).  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 6.3.5).  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.

6.3.  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.

6.3.1.  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 a GSS acceptor, MUST invoke the GSS EAP mechanism
   (either spontaneously or as the result of a mechanism negotiation)
   and send an EAP-Identity/Request message to the User Agent, acting as
   a GSS initiator.

6.3.2.  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.



Howlett & Hartman        Expires April 21, 2013                [Page 10]


Internet-Draft                 SAML RADIUS                  October 2012


   Profile-specific rules for the contents of the <samlp:AuthnRequest>
   element are given in Section 6.4.1.

6.3.3.  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
   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.

6.3.4.  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 6.4.2.

6.3.5.  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.

   To complete the profile, the Relying Party creates a GSS security
   context for the User Agent.

6.4.  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



Howlett & Hartman        Expires April 21, 2013                [Page 11]


Internet-Draft                 SAML RADIUS                  October 2012


   Subject.

6.4.1.  <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
   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.

6.4.2.  <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.




Howlett & Hartman        Expires April 21, 2013                [Page 12]


Internet-Draft                 SAML RADIUS                  October 2012


   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.

6.4.3.  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.

   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.

6.4.4.  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.

6.4.5.  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.

6.4.6.  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



Howlett & Hartman        Expires April 21, 2013                [Page 13]


Internet-Draft                 SAML RADIUS                  October 2012


   scope of this profile.

6.4.7.  Metadata Considerations

   There are no metadata considerations particular to this binding.

7.  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.

   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.

7.1.  Required Information

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

   Contact information: iesg@ietf.org

   Description: Given below.

   Updates: None.

7.2.  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.









Howlett & Hartman        Expires April 21, 2013                [Page 14]


Internet-Draft                 SAML RADIUS                  October 2012


   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

   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.

7.3.  Profile Description

7.3.1.  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 7.3.4.

   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 .

7.3.2.  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.



Howlett & Hartman        Expires April 21, 2013                [Page 15]


Internet-Draft                 SAML RADIUS                  October 2012


7.3.3.  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.

7.3.4.  Metadata Considerations

   There are no metadata considerations particular to this binding.

8.  Acknowledgements

   TODO: Where should these go?  Need to acknowledge OASIS SSTC,
   UoMurcia, Scott and Steven.

9.  Security Considerations

   TODO

10.  IANA Considerations

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

11.  References

11.1.  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",



Howlett & Hartman        Expires April 21, 2013                [Page 16]


Internet-Draft                 SAML RADIUS                  October 2012


                                            draft-ietf-abfab-gss-eap-04
                                            (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.

11.2.  Informative References

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

   [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.

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




Howlett & Hartman        Expires April 21, 2013                [Page 17]


Internet-Draft                 SAML RADIUS                  October 2012


   [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.,
                                            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



Howlett & Hartman        Expires April 21, 2013                [Page 18]


Internet-Draft                 SAML RADIUS                  October 2012


                                            (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





























Howlett & Hartman        Expires April 21, 2013                [Page 19]


Html markup produced by rfcmarkup 1.129d, available from https://tools.ietf.org/tools/rfcmarkup/