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1993-07-13 - Re: xor data hiding?

Header Data

From: “Perry E. Metzger” <pmetzger@lehman.com>
To: cypherpunks@toad.com
Message Hash: 89e8fca3cd3df690d27d53cd97c692d6f46d5b594db718e400cf946a1c223a7a
Message ID: <9307130306.AA15377@snark.shearson.com>
Reply To: <9307130230.AA20305@triton.unm.edu>
UTC Datetime: 1993-07-13 03:06:58 UTC
Raw Date: Mon, 12 Jul 93 20:06:58 PDT

Raw message

From: "Perry E. Metzger" <pmetzger@lehman.com>
Date: Mon, 12 Jul 93 20:06:58 PDT
To: cypherpunks@toad.com
Subject: Re: xor data hiding?
In-Reply-To: <9307130230.AA20305@triton.unm.edu>
Message-ID: <9307130306.AA15377@snark.shearson.com>
MIME-Version: 1.0
Content-Type: text/plain



J. Michael Diehl <mdiehl@triton.unm.edu> says:
>      I heard something interesting which made me think. (gasp)  
>  
>      I heard that if you encrypt a file with the xor encryption alg.
> multiple times with different keys, you get an encrypted file with a
> coorisponding effective key which has some interesting properties.  The key
> in such a system would have a length equal to the Least Common Multiple of
> the lengths of the original key.

Sadly, the Friedmans already cracked the "multiple repeating xored
keys" cypher a while back -- about fifty years ago.

Don't be embarassed, by the way -- everyone comes up with cyphers that
have been cracked before. However, I would suggest reading "The
Codebreakers" and the current literature before proposing new systems.

Perry

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