Bryan Mongeau wrote:
> I have a question regarding the existence of a defense mechanism against
> Matsui's Linear Cryptanalysis and other forms of known-plaintext attacks.
> <?xml version="1.0" encoding="us-ascii"?> ( total of 41 chars )
>
> All XML documents adhering to the same standards bear the same headers.
> Considering a small document ( ~80 chars ) would have already more than half its
> plaintext known, isn't this extremely vulnerable to known-plaintext attacks?
> Are they any means of protecting oneself if your plaintext has a predictable
> component (such as the case with XML headers)?
The attack works against classes of iterated block ciphers, and a stream
cipher such as RC4, used properly (no key reuse, rekeying every 2^n bytes,
discarding the first M bytes of the keystream), would be a solution.
The new AES cipher, Rijndael, is resistant to this attack.
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