[jlcooke@certainkey.com: Re: SHA-0]

From: Jean-Luc Cooke
Date: Fri Aug 13 2004 - 08:22:21 EST



--- Begin Message --- No it does not...we think...

SHA-0 is the nick-name for the first draft of SHA put forward by NIST/NSA of
the US Gov't. Cryptographers got up in arms about how it had a "lazy bit" (a
bit that does not effect the output of the hash) and how it did not have
enough rounds.

So, they named the "first" SHA SHA-0 because it wasn't good enough. And
SHA-1 the "first released" SHA. SHA-1 was designed to be stronger than
SHA-0 in at least one of the ways SHA-0 was recently exploited.

Still, this is a very interesting development in the field of hash function
cryptanalysis. Biham should be co-presenting a paper explain how they did
it soon. They give allusion to a possible attack on SHA-1...but I hear it's
still theoretical.

SHA-256 is looking better. Though SHA-1 is still strong enough, it may not
last to its 2012 "expiry date" for vulnerabilities to collision attacks set
by Lenstra/Verheul in (1).

Cheers,

JLC

(1) Selecting Cryptographic Key Sizes</a> by Arjen K. Lenstra, Eric R. Verheul
<http://www.cacr.math.uwaterloo.ca/conferences/1999/ecc99/lenstra.doc>

On Thu, Aug 12, 2004 at 11:12:03PM -0400, James Morris wrote:
> Hi Jean-Luc,
>
> I read on sci.crypt about the SHA-0 collision, do you know if this casts
> doubt on SHA-1?
>
> - James
> --
> James Morris
> <jmorris@xxxxxxxxxx>
>

--- End Message ---