On Wed, Oct 5, 2011 at 5:49 PM, Luke Howard <[email protected]> wrote:
> So, I propose that we replace the existing GSS channel binding and extension 
> wrap/MIC tokens (respectively) with RFC 3961 checksums using the CRK with the 
> following key usage numbers:
>
> KEY_USAGE_CHANNEL_BINDINGS_MIC      TBD
> KEY_USAGE_ACCEPTOR_TOKEN_MIC         TBD
> KEY_USAGE_INITIATOR_TOKEN_MIC       TBD
>
> A nice property of this is that we can efficiently deal with large GSS 
> channel bindings (because we are sending a checksum rather than a wrap token; 
> recall, we previously sent a wrap token so that the acceptor could ignore 
> channel bindings without disturbing its sequence state).
>
> Comments?

Mostly only that I approve.

Note that if you really did want to use an RFC4121 per-msg token
library and still not get forced into sequencing you have two options
available:

a) there are no sequencing problems, since RFC4121 can handle
out-of-sequence tokens;
b) you could create separate "contexts" for internal each use of
RFC4121, with different keys in each case, all derived from the EAP
keys.

Now, RFC4121 is going to require RFC3961/2 anyways, so using RFC3961/2
directly in this part of GSS-EAP is hardly a burden -- unless you have
an API to the first but not the second...

Nico
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