From: Michael Paul Johnson <mpj@netcom.com>
Date: Sat, 23 Dec 1995 04:30:20 +0800
To: prz@acm.org
Subject: Weak keys in Diamond Encryption Algorithm fixed.
Message-ID: <Pine.SUN.3.91.951222091711.7092B-100000@netcom12>
MIME-Version: 1.0
Content-Type: text/plain


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*******

There is a class of weak keys in the Diamond Encryption Algorithm.  These are
the ones that result in all of the individual substitution arrays being the
same.  This has a probability of about 2^-40 of happening, and is not the
basis of a practical attack, but it is interesting, anyway.  Thanks to
Colin Plumb for pointing this out. 

This weakness has been eliminated in the Diamond2 Encryption Algorithm.
See ftp://ftp.csn.net/mpj/public/diamond2.ps.gz for details.  If you are in
the USA or Canada, there is a reference implementation (as well as the above
document) in
ftp://ftp.csn.net/mpj/I_will_not_export/crypto_???????/file/diamond2.zip,
where the ??????? is revealed in ftp://ftp.csn.net/mpj/README along with
an export warning.

*******

I've also put an updated description of another algorithm, the Sapphire II
Stream Cipher, in ftp://ftp.csn.net/mpj/public/sapphire.ps.gz and a reference
implementation in
ftp://ftp.csn.net/mpj/I_will_not_export/crypto_???????/file/sapphire.zip

*******

DLOCK2.ZIP and SAPPHIRE.ZIP are also on the Colorado Catacombs BBS at
303-772-1062.

*******

You are invited to review the above algorithms and let me know if you find
any weakness in them.

*******

These are not commercial products, and this is not an advertisement.  This
is an electronic publication for the enjoyment of people who are interested
in cryptography for constructive purposes.

Merry Christmas!


                  ___________________________________________________________
                 |                                                           |
 |\  /| |        | Michael Paul Johnson  Colorado Catacombs BBS 303-772-1062 |
 | \/ |o|        | PO Box 1151, Longmont CO 80502-1151 USA   Jesus is alive! |
 |    | | /  _   | mpj@csn.org aka mpj@netcom.com m.p.johnson@ieee.org       |
 |    |||/  /_\  | ftp://ftp.csn.net/mpj/README.MPJ          CIS: 71331,2332 |
 |    |||\  (    | ftp://ftp.netcom.com/pub/mp/mpj/README  -. --- ----- .... |
 |    ||| \ \_/  | PGPprint=F2 5E A1 C1 A6 CF EF 71  12 1F 91 92 6A ED AE A9 |
                 |___________________________________________________________|

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