Status of attacks on AES?

[John R. Black]

On Thu, May 04, 2006 at 10:30:40AM -0500, Marcos el Ruptor wrote:
> 
> http://defectoscopy.com/forum/viewtopic.php?t=3
> 
> Expect new attacks soon enough.
> 
I skimmed this.  The start of the article says that after 3 rounds AES
achieves perfect diffusion?!

A simple square attack (that I teach in class in about 60 mins) recovers 
the key of 4-round AES with 256 chosen-plaintexts.  The six-round attack
isn't too much harder.

Square (the cipher that preceded Rijndael and is very similar) was 8 rounds
to get past the 6-round attack.  During the AES vetting process they went
to 10 rounds for extra assurance (as much as anyone gets assurances from
the black art of blockcipher design).

john//

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