Symmetric ciphers as hash functions

[Greg Rose]

At 01:33 2005-11-01 -0600, Travis H. wrote:
>The latest hashes, such as SHA-1, gave up on Feistel.

Not so... the SHA family are all unbalanced Feistel structures. 
Basically, for SHA-1 a complex function of 4 words and key material 
(in this case expanded data to be hashed) is combined with the fifth 
word. The fact that the four words don't change is the giveaway that 
it's a feistel structure. The later SHAs have a more complicated 
structure, blurring the boundary a bit, but I'd still call them 
unbalanced Feistel.

Greg.



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