draft-josefsson-password-auth-00.txt

[Simon Josefsson]

Hi all!

The SASL WG discussed new password-based mechanisms, and there were
some discussions at the last meeting to do this through a GSS-API
mechanism instead.  I mentioned on jabber that I had been working on a
draft to do that, and while it is far from finished I thought I'd
publish it early to gauge interest in the work.

My idea is to specify a challenge/response protocol that is (somewhat)
agnostic to the framework (GSS-API or SASL) and then specify how that
protocol is used in these two frameworks.  Since the wire protocol is
highly influenced by GSS-API and SASL concepts, the mappings for how
to use the protocol in GSS-API or SASL is just one page.  The
cryptographic primitive is right now HMAC-SHA-256 but the intention is
that other MACs, including non-HMAC based approaches such as AES-CMAC
(RFC 4493) can be supported easily.

To make it easier to implement this as a SASL mechanism, I'm sure the
document could say a lot more.  I intend to include sample code for
DER length encoding (it is only a few lines of C code), which is
something some people consider complex.  Providing an entire
implementation of the GS2-YGZBCUXPNWNVHSI mechanism would be possible
to include, I believe there is not a lot of code to do it.  This might
make it easier for IMAP/SMTP implementers to start using it quickly.

The document is available from the IETF servers, see the announcement
below.

Comments?

I'm cc:ing this to the password-auth mailing list that I created for
discussion of the document.  Some discussions of the document may be
off-topic for the SASL/KITTEN lists, and the WG chairs may prefer to
see it discussed elsewhere (let me know!), so consider dropping the
IETF lists when starting such a thread.  To subscribe to the list, and
for other resources related to this effort, see:

       http://josefsson.org/password-auth/

Even if there isn't much uptake from the SASL community on this idea,
I believe having a password-based GSS-API mechanism is an important
contribution and I'll continue working on that.  How much the document
talks about SASL will depend on the interest.  Through GS2, it will
eventually be possible to use it in SASL anyway.

/Simon

Internet-Drafts at ietf.org writes:

> 	Title		: A Password-based Authentication Protocol
> 	Author(s)	: S. Josefsson
> 	Filename	: draft-josefsson-password-auth-00.txt
> 	Pages		: 16
> 	Date		: 2007-3-28
> 	
>    There is a lack of a simple, standardized, secure and modern
>    password-based mechanism for user authentication in application
>    protocols.  This document specify a challenge/response protocol that
>    provide password-based authentication services.  We describe how the
>    protocol may be used as a GSS-API mechanism and, using the GS2
>    framework, how it may be used as a SASL mechanism.  The protocol
>    supports HMAC-SHA-256 as the mandatory to implement algorithm, and it
>    supports channel bindings.  The intended use is by application
>    protocol that today use CRAM-MD5 or DIGEST-MD5 via SASL, or by GSS-
>    API applications that needs a password based method.  The protocol is
>    applicable to other environments, such as EAP, should the need arise.
>
>    See <http://josefsson.org/password/> for more information.
>
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-josefsson-password-auth-00.txt