A Simple Authentication and Security Layer (SASL) and GSS-API Mechanism for the Security Assertion Markup Language (SAML)
RFC 6595

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Internet Engineering Task Force (IETF)                       K. Wierenga
Request for Comments: 6595                           Cisco Systems, Inc.
Category: Standards Track                                        E. Lear
ISSN: 2070-1721                                       Cisco Systems GmbH
                                                            S. Josefsson
                                                                  SJD AB
                                                              April 2012

A Simple Authentication and Security Layer (SASL) and GSS-API Mechanism
           for the Security Assertion Markup Language (SAML)

Abstract

   The Security Assertion Markup Language (SAML) has found its usage on
   the Internet for Web Single Sign-On.  The Simple Authentication and
   Security Layer (SASL) and the Generic Security Service Application
   Program Interface (GSS-API) are application frameworks to generalize
   authentication.  This memo specifies a SASL mechanism and a GSS-API
   mechanism for SAML 2.0 that allows the integration of existing SAML
   Identity Providers with applications using SASL and GSS-API.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6595.

Wierenga, et al.             Standards Track                    [Page 1]
RFC 6595          A SASL and GSS-API Mechanism for SAML       April 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
   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
      1.1. Terminology ................................................4
      1.2. Applicability ..............................................4
   2. Authentication Flow .............................................5
   3. SAML SASL Mechanism Specification ...............................7
      3.1. Initial Response ...........................................8
      3.2. Authentication Request .....................................8
      3.3. Outcome and Parameters .....................................9
   4. SAML GSS-API Mechanism Specification ...........................10
      4.1. GSS-API Principal Name Types for SAML .....................11
   5. Examples .......................................................11
      5.1. XMPP ......................................................11
      5.2. IMAP ......................................................15
   6. Security Considerations ........................................17
      6.1. Man-in-the-Middle and Tunneling Attacks ...................17
      6.2. Binding SAML Subject Identifiers to Authorization
           Identities ................................................17
      6.3. User Privacy ..............................................18
      6.4. Collusion between RPs .....................................18
      6.5. Security Considerations Specific to GSS-API ...............18
   7. IANA Considerations ............................................18
      7.1. IANA Mech-Profile .........................................18
      7.2. IANA OID ..................................................19
   8. References .....................................................19
      8.1. Normative References ......................................19
      8.2. Informative References ....................................21
   Appendix A. Acknowledgments .......................................22

Wierenga, et al.             Standards Track                    [Page 2]
RFC 6595          A SASL and GSS-API Mechanism for SAML       April 2012

1.  Introduction

   Security Assertion Markup Language (SAML) 2.0 [OASIS-SAMLv2-CORE] is
   a set of specifications that provide various means for a user to be
   identified to a Relying Party (RP) through the exchange of (typically
   signed) assertions issued by an Identity Provider (IdP).  It includes