Subject: Re: [kitten] sasl saml and sasl openID

From: Sam Hartman <[email-masked]>
Date: Wed, 01 Dec 2010 13:06:59 -0500

>>>>> "Klaas" == Klaas Wierenga (kwiereng) <[email-masked]> writes:

    Klaas> Ehm, I was thinking of computing a key with the saml authn
    Klaas> req and the key material from tls as input, would that work?

I'm a bit dubious of using the key from TLS as part of verifying the TLS
endpoints (which is what CB does).

---

From: Jeffrey Hutzelman <[email-masked]>
Date: Wed, 01 Dec 2010 13:48:14 -0500

> endpoints (which is what CB does).

Me too.  If I recall correctly, when we were working on defining CB for 
TLS, one of the conclusions we came to was that the TLS master secret does 
_not_ constitute a unique channel binding, which is why we use the entire 
finished message instead.  Further, using TLS's keying material in any way 
other than as defined in TLS runs the risk of inadvertently sharing keying 
material between what should be separate cryptographic contexts.

Finally, it's really not appropriate for a GSS/SASL mechanism to assume 
there is an underlying TLS channel.  Channel bindings are somewhat abstract 
by design; a mechanism should work with _any_ channel binding.

-- Jeff