Re: Braided ciphers

From: Mok-Kong Shen (mok-kong.shen@t-online.de)
Date: 02/10/03 

From: Mok-Kong Shen <mok-kong.shen@t-online.de>
Date: Mon, 10 Feb 2003 00:48:46 +0100

David Wagner wrote:
>
> Ahh, so are you saying you're seeking a way to compose two block ciphers
> so that the result is at least as strong as the stronger of the two
> ciphers? If so, there are better ways to achieve this than "braiding".
> For instance, one can run the two ciphers in OFB or CTR mode and xor
> their outputs. Or, one can use superencryption (first encrypt with the
> first block cipher, then encrypt that result with the second cipher),
> which should do the trick (modulo a few theoretical issues, a la Maurer
> and Massey).

If I understand correctly, OP's scheme needs at least
three streams, in which case one stream is used to
choose bits from the other two. I suppose that it
would be comparable to xor-ing all three.

M. K. Shen

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