On Tue, May 08, 2001 at 01:01:34AM -0500, Scott Gregory Miller wrote:
> > > > * to pad data to a power of 2, you repeat the data
> > > No.  This lends an attack as well, since the attacker can try and assume
> > > that several of the last blocks of the file are the same. 
> > 
> > Does that matter given that the mode we are using is rolling?
> Yes, since its only rolling within a block.  After two blocks you start
> getting the same encryption (your XORing all zeros, so you're essentially
> just encrypting as a stream cipher).  I'm not saying this does give a
> cryptanalyst any info, but it might.

" * to pad data to a power of 2, you repeat the data"

How does that involve XORing all zeros? Repeating the same data will not
cause the ciphertext to repeat as far as I can tell...

<>

-- 
'DeCSS would be fine. Where is it?'
'Here,' Montag touched his head.
'Ah,' Granger smiled and nodded.

Oskar Sandberg
md98-osa at nada.kth.se

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