Realm Crossover for SASL and GSS-API via Diameter
draft-vanrein-diameter-sasl-04
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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Internet-Draft Diameter SASL January 2021
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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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