Subject: Re: [OAUTH-WG] Signature crypto

From: "Meadhbh Hamrick (Infinity Linden)" <[email-masked]>
Date: Fri, 27 Nov 2009 09:44:03 -0800

I thought we were talking about negotiating the hash associated with rsa signature generation. No matter, the issues are the same. You have to select a common selection from multiple choices. If we're talking about algorithm negotiation, we could just as easily use the same mechanism for selecting an option from sha1+rsa, sha256+rsa, ecdsa, etc. As we use to select an option from hmac, mdc, etc.

"Manger, James H" <[email-masked]> wrote:

>>> Sounds reasonable if all you need to negotiate are hash algorithm names.
>>> Is that the case?
>
>> Yes.
>
>Not quite.
>OAuth (at least the authentication part) mainly needs a MAC algorithm, not a hash algorithm.
>HMAC is one popular MAC algorithm that is build from a hash algorithm.
>However, there are other MAC algorithms — based on block ciphers for instance (eg CMAC-AES).
>The hash registry http://www.iana.org/assignments/hash-function-text-names/ is not really going to help.
>
>P.S. The body-signing OAuth extension is the one place that uses a hash (not a MAC) directly.
>
>James Manger
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