From: Rolf Michelsen <Rolf.Michelsen@delab.sintef.no>
Date: Mon, 4 Jul 94 05:10:08 PDT
To: Cypherpunks mailing list <cypherpunks@toad.com>
Subject: Re: Dr. Dobbs Dev. Update 1/5 July 94 & Schneier
In-Reply-To: <m0qJvy4-0002FgC@chinet>
Message-ID: <Pine.3.88.9407041313.B8036-0100000-0100000-0100000-0100000@svme.er.sintef.no>
MIME-Version: 1.0
Content-Type: text/plain


On Fri, 1 Jul 1994, Bruce Schneier wrote:

>      Synthesis of Public-Key Algorithms:  There are a lot of
> public-key digital signature algorithms in the literature based
> on the problem of taking discrete logarithms in a finite field: 
> ElGamal, Schnorr, and the Digital Signature Standard (DSS) are
> three examples.  Nyberg and Rueppel presented a paper which
> unified all of these algorithms (108 in total) into one unified
> family.  They also showed how to do encryption with all of them. 

Hrm...  As far as I recall they showed how to do _message_recovery_ (not 
encryption) with the discrete log signature functions.  Message recovery 
and encryption are two quite different things for assymetric schemes such as 
the discrete log ones (as opposed to RSA).  Correct me if I'm wrong...

>      Visual Cryptography:  Shamir developed a one-time-pad
> cryptosystem that is suitable for encrypting visual images.  The
> key is a pattern of black and white pixels on a transparency; the
> ciphertext is another pattern of black and white pixels.  Overlay
> the key on the ciphertext and the message appears.  This is
> unconditionally secure; even alien civilizations with undreamed-
> of computing power cannot break this cryptosystem.  Applications
> include sending an encrypted message via fax: the receiver can
> carry the key transparency with him and can receive the encrypted
> fax from an insecure machine.  Cool stuff.

Yea, cool stuff, especially if the fax doesen't shrink the transmitted 
picture :-)  This is also great for demonstrating crypto to newbies by 
showing that noise+noise=picture.

-- Rolf



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Rolf Michelsen                           "Standards are wonderful --     
Email: rolf.michelsen@delab.sintef.no      everyone should have one"
Phone: +47 73 59 87 33                       -- Ancient FORTH proverb
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