Columbia crypto box

[bear]

On Mon, 10 Feb 2003, Matthew Byng-Maddick wrote:

>On Sun, Feb 09, 2003 at 11:43:55PM -0500, Donald Eastlake 3rd wrote:
>> been that you either throw away the first 256 bytes of stream key output
>> or use a different key on every message. WEP does neither. TKIP, the new
>
>You NEVER, EVER, re-use the key for a stream cipher, if you do, you might
>as well just give up. By re-using the key, I can get
>plaintext (combinator) plaintext, which is easier to solve than
>plaintext (combinator) cipherstream.
>
>It's one of those things, like re-using a pad.

Actually, it is re-using a pad, exactly.  It's just a pseudorandom
pad (stream cipher) instead of a one-time pad.

And while WEP had problems, it didn't have that particular problem.
New messages with the "same" key would use a later chunk of the
cipherstream pad under WEP.

			Bear


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