From: ghio@temp0130.myriad.ml.org (Matthew Ghio)
Date: Mon, 6 Oct 1997 03:07:43 +0800
To: cypherpunks@cyberpass.net
Subject: Re: Quor's cipher
In-Reply-To: <199710042151.WAA03454@notatla.demon.co.uk>
Message-ID: <199710051843.OAA02599@myriad>
MIME-Version: 1.0
Content-Type: text/plain



Antonomasia <ant@notatla.demon.co.uk> wrote:

> How are you planning to detect which bytes are passed in this way ?
> Chosen plaintext attacks would do it, and show where (a+b)^(a0+b0) == 0.
> Looks like you've just doubled our progress.

It doesn't take chosen plaintext, just known plaintext.

> 
> If the key is reused with a different message I don't think there's a
> weakness.  An IV is a good idea, but aren't we _attacking_ this thing ?

Lack of an IV is a problem with almost any cipher, but it seems especially
so here.