Kitten T. Hansen
Internet-Draft AT&T Laboratories
Updates: 5802 (if approved) April 11, 2014
Intended status: Informational
Expires: October 13, 2014

SCRAM-SHA-256 and SCRAM-SHA-256-PLUS SASL Mechanisms
draft-hansen-scram-sha256-00

Abstract

This document registers the SASL mechanisms SCRAM-SHA-256 and SCRAM-SHA-256-PLUS. It also updates RFC 5802 in minor ways.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on October 13, 2014.

Copyright Notice

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Table of Contents

1. Introduction

This document registers the SASL mechanisms SCRAM-SHA-256 and SCRAM-SHA-256-PLUS.

The registration form for the SCRAM is also updated.

Note: this paragraph may be removed before publication.
This document was written because [RFC5802] requires that new SASL mechanisms in the SCRAM family be subject to IETF review. This document is being discussed on the kitten@ietf.org mailing list.

2. SCRAM-SHA-256 and SCRAM-SHA-256-PLUS

The SCRAM-SHA-256 and SCRAM-SHA-256-PLUS SASL mechanism are defined in the same way that SCRAM-SHA-1 and SCRAM-SHA-1-PLUS are defined in [RFC5802], except that the hash function for HMAC() and H() uses SHA-256 instead of SHA-1 [RFC6234].

For the SCRAM-SHA-256/SCRAM-SHA-256-PLUS SASL mechanisms, servers SHOULD announce a hash iteration-count of at least 4096.
!!!!!!!!!!!!!!!! Note that the appropriate value to specify here is being actively discussed. !!!!!!!!!!!!!!!!

The GSS-API mechanism OID for SCRAM-SHA-256 is [to be assigned by IANA] (see Section 3).

This is a simple example of a SCRAM-SHA-256 authentication exchange when the client doesn't support channel bindings (username 'user' and password 'pencil' are used):

C:
n,,n=user,r=rOprNGfwEbeRWgbNEkqO
S:
r=rOprNGfwEbeRWgbNEkqO%hvYDpWUa2RaTCAfuxFIlj)hNlF$k0,
s=W22ZaJ0SNY7soEsUEjb6gQ==,i=4096
C:
c=biws,r=rOprNGfwEbeRWgbNEkqO%hvYDpWUa2RaTCAfuxFIlj)hNlF$k0,
p=dHzbZapWIk4jUhN+Ute9ytag9zjfMHgsqmmiz7AndVQ=
S:
v=6rriTRBi23WpRR/wtup+mMhUZUn/dB5nLTJRsjl95G4=

3. IANA Considerations

The IANA registry for the SCRAM family of SASL mechanisms is updated as follows:

4. Acknowledgements

This document benefited from discussions on the KITTEN WG mailing list. The author would like to specially thank ...

5. References

5.1. Normative References

[RFC5802] Newman, C., Menon-Sen, A., Melnikov, A. and N. Williams, "Salted Challenge Response Authentication Mechanism (SCRAM) SASL and GSS-API Mechanisms", RFC 5802, July 2010.
[RFC6234] Eastlake, D. and T. Hansen, "US Secure Hash Algorithms (SHA and SHA-based HMAC and HKDF)", RFC 6234, May 2011.

5.2. Informative References

[RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and Security Layer (SASL)", RFC 4422, June 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.

Author's Address

Tony Hansen AT&T Laboratories 200 Laurel Ave. South Middletown, NJ 07748 USA EMail: tony+scramsha256@maillennium.att.com