Re: HMAC-SHA-1 security question

<osmo.sis@xxxxxxxxx> wrote in message news:b9e7d3c5-5f4d-4c4a-868e-2dee0b940ee0@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi
I'd have an interesting question.

We know that HMAC-SHA 1 is a hash value H, computed from a base input
value V and a secret key K.
In formula: H = HAMC-SHA-1(K, V).

Now, let us assume an attacker knows H and V. Only the K is unknown.
I'd like to know if there was any possibility to make conclusions
about the secret key K?
Or, furthermore, do values for H and V exist that make it possible to
conclude about K? Even if it was just one bit one can make conclusions
about? Any ideas?

Please, I'd like to hear some input on this from somebody...


If you look at the updated HMAC proof it makes it rather clear. If such an attack were found it would be major cryptographic news, and mean that SHA-1 is completely and utterly broken. Right now SHA-1 is wounded, but certainly not broken to this degree.
Joe

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