Re: [CHANNEL-BINDING] Re: draft-ietf-sasl-gs2 AD review comments

On Tue, Oct 09, 2007 at 05:44:47PM -0400, Jeffrey Hutzelman wrote:
> Really, I don't care what the API looks like or what part of the
> implementation is responsible for adding the prefix.  What I care
> about is who is responsible for specifying how the prefix is encoded
> and transported.  Does the application protocol specification do this,
> possibly by transporting two protocol fields (a name and an octet
> string)?  Or is the prefix part of the octet-string channel binding
> data?

The channel binding octet string and the prefix US-ASCII string are both
*just* that.  Prefixing the latter to the former is feasible without
ambiguity provided that: the prefixes are unique and that they are
always used.  No separator character is needed (but if one was needed
I'd prefer ':' over NUL).

I believe the text of the I-D is clear on the above.  Thus your protocol
issues are taken care of.

The more I think about the who's-responsible-for-prefixing issue the
more I realize that the I-D shouldn't speak to that issue.  I could see
an operating system where all channels report channel bindings with the
prefix already included, another where only some do, and another where
none do -- but in all cases the applications can deal and interop
provided that the applications know which channels include the prefix
when and which don't.

Thus, I'm inclined to believe that the issue in question requires no
clarfication beyond saying that the ambiguity is intentional.

Nico
-- 

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