[18820] in cryptography@c2.net mail archive
Re: Symmetric ciphers as hash functions
daemon@ATHENA.MIT.EDU (Greg Rose)
Tue Nov 1 11:42:51 2005
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
Date: Tue, 01 Nov 2005 08:33:39 -0800
To: "Travis H." <solinym@gmail.com>
From: Greg Rose <ggr@qualcomm.com>
Cc: Arash Partow <arash@partow.net>, cryptography@metzdowd.com
In-Reply-To: <d4f1333a0510312333k44e882e7l75adbff3a12b02c3@mail.gmail.co
m>
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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