[87526] in Cypherpunks
Re: Fwd: Re: Quor's cypher
daemon@ATHENA.MIT.EDU (Anonymous)
Thu Oct 2 05:05:23 1997
Date: Thu, 2 Oct 1997 09:52:51 +0200 (MET DST)
To: cypherpunks@cyberpass.net
From: nobody@replay.com (Anonymous)
In-Reply-To: <199709292301.AAA04109@notatla.demon.co.uk>
Reply-To: nobody@replay.com (Anonymous)
Antonomasia <ant@notatla.demon.co.uk> wrote:
> My attack takes a long chunk of known text and looks for repetition.
>
> ppppppppppppppp.11.pppppppppppppppppppppp
> ccccccccccccccc.22.cccccccccccccccccccccc
>
> When a two neighbouring p-c pairs are the same you can test
> whether they have the same value of a and b.
> (That is a_n == a_n+1 and b_n == b+n+1, a != b usually.)
>
> This involves 16 inputs to each byte - very cheap.
> What I really want next is to know "a".
Wouldn't this only happen (on average) in one out of every 65536 p-c
pairs? Since the state array is changed entirely with every 128 bytes
encrypted, 1 out of 2^16 doesn't seem to help much.
