From: raph@netcom.com (Raph Levien)
Date: Tue, 13 Dec 94 09:49:01 PST
To: cypherpunks@toad.com
Subject: More 40-bit RC4 nonsense
Message-ID: <199412131742.JAA27330@netcom5.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


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   If I recall correctly, the first byte out of the RC4 stream has
about a 40% chance of being the first byte of the key. Thus, if the
40-bit "secret" part of the key is the _beginning_ of the full 128-bit
key, then the keyspace is effectively reduced by about seven bits,
meaning that I would be able to crack a key on my PC in a couple of
days or so.
   Of course, if the "clear" 88 bits went first, there would be no
advantage whatsoever. The SSL document very carefully does not say
how they combine the two key parts to form the 128-bit key. Does
anyone know?

Raph

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