Realm Crossover for SASL and GSS-API via Diameter
draft-vanrein-diameter-sasl-04

Document Type Active Internet-Draft (individual)
Authors Rick van Rein  , Henri Manson 
Last updated 2021-01-26
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Network Working Group                                        R. Van Rein
Internet-Draft                                           OpenFortress BV
Intended status: Informational                                 H. Manson
Expires: July 30, 2021                                           Mansoft
                                                        January 26, 2021

           Realm Crossover for SASL and GSS-API via Diameter
                     draft-vanrein-diameter-sasl-04

Abstract

   SASL and GSS-API are used for authentication in many application
   protocols.  This specification extends them to allow credentials of a
   home realm to be used against external services.  To this end, it
   introduces end-to-end encryption for SASL that is safe to relay
   through a foreign server.

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   document authors.  All rights reserved.

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Van Rein & Manson         Expires July 30, 2021                 [Page 1]
Internet-Draft                Diameter SASL                 January 2021

   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Messages of SXOVER-PLUS . . . . . . . . . . . . . . . . . . .   4
     2.1.  Preparation for Messaging . . . . . . . . . . . . . . . .   4
     2.2.  Initial Client-to-Server Message  . . . . . . . . . . . .   5
     2.3.  Initial Server-to-Client Message  . . . . . . . . . . . .   5
     2.4.  Continued Client-to-Server Messages . . . . . . . . . . .   6
     2.5.  Continued Server-to-Client Messages . . . . . . . . . . .   7
     2.6.  Using SXOVER-PLUS with GSS-API  . . . . . . . . . . . . .   7
     2.7.  Application Key Derivation  . . . . . . . . . . . . . . .   8
   3.  AVP Definitions for SASL in Diameter  . . . . . . . . . . . .   9
     3.1.  SASL-Mechanism  . . . . . . . . . . . . . . . . . . . . .   9
     3.2.  SASL-Token  . . . . . . . . . . . . . . . . . . . . . . .  10
     3.3.  SASL-Channel-Binding  . . . . . . . . . . . . . . . . . .  10
     3.4.  NAS-Port-Type for SASL Services . . . . . . . . . . . . .  10
   4.  Diameter Session Requirements for SASL  . . . . . . . . . . .  11
   5.  Diameter Message Requirements for SXOVER-PLUS . . . . . . . .  11
     5.1.  C2S-Init Requests over Diameter . . . . . . . . . . . . .  11
     5.2.  S2C-Init Responses over Diameter  . . . . . . . . . . . .  12
     5.3.  C2S-Cont Requests over Diameter . . . . . . . . . . . . .  12
     5.4.  S2C-Cont Responses over Diameter  . . . . . . . . . . . .  13
   6.  Running Diameter as a SASL Backend  . . . . . . . . . . . . .  14
     6.1.  Diameter is an SCTP service . . . . . . . . . . . . . . .  14
     6.2.  Reliance on DANE and DNSSEC . . . . . . . . . . . . . . .  14
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .  16
   Appendix A.  Centralised handing of SASL over Diameter  . . . . .  18
   Appendix B.  Acknowledgements . . . . . . . . . . . . . . . . . .  21
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  21

1.  Introduction

   It is common for Internet users to combine services from a varierity
   of providers.  An ad hoc practice has arisen of using local identity
   schemes for each of these providers.  There is no integration of
   identity systems, and the practice reduces the control of users over
   their online identity.  A solution to this is support for realm
   crossover, where an externally acquired service can make a callback
   to a home realm to authenticate a user's identity and use that for
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