Gao's Chaos Cryptosystem

GCC(Gao's Chaos Cryptosystem)
GCC uses the newest chaos logic and is conventional cryptosystem stream 
cipher
encryption. It is high speed and allows variable-length keys, making it 
very
reliable and suitable for use in multimedia.

http://www.iisi.co.jp/reserch/GCC-over.htm


Chaos InforGuard
GCC(Gao's Chaos Cryptosystem) security application.
High speed,variable-length keys,high reliability,and user friendliness 
allow you
to easily encrypt an entire harddisc.Can be used with Windows3.1 & 
Windows95.

http://www.iisi.co.jp/vcs/software/infoguard-e1621.html


Chaos-mail
Internet Mailer Using Gao's Chaos Cryptosystem
Chaos-mail is a cryptosystem mailer for use on Windows95,which using GCC 
and Chaos
MAM, gives you the ability to encrypt/decrypt and verify mail. 
Chaos-mail is a
cryptosystem mailer for user on Windows 95 which, using GCC and Chaos 
MAM, gives
you the ability to encrypt, decrypt, and verify mail. Not only is it 
fast,
reliable, and user-friendly, but it is also very suitable for multimedia 
because
of its non-biased treatment of data.

http://www.iisi.co.jp/vcs/software/chaosmail-e.htm



______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com

At 12:37 AM 9/6/97 PDT, Nobuki Nakatuji wrote:
>GCC(Gao's Chaos Cryptosystem)
>GCC uses the newest chaos logic and is conventional cryptosystem 
>stream cipher encryption. It is high speed and allows variable-length keys,
>making it very reliable and suitable for use in multimedia.
>http://www.iisi.co.jp/reserch/GCC-over.htm
>[Products using it, user-friendliness, etc.]

Good user interfaces and high speed are important, but not enough.
How strong is the cypher?  Where is the academic research behind it?
What is the algorithm?  Why should we trust it?  Who else has tested it?
Other people have built cyphers based on chaotic systems, and found
they were weak when analyzed properly.  Building good cryptosystems is
difficult.

The web page doesn't give any details about the algorithm,
except saying that it uses chaos and strange attractors,
uses variable-length keys, and has a structure that uses
XOR of the stream cypher with the plaintext.
It does say the algorithm has a 0-1 balance of 0.5/0.5 
(which any good cryptosystems do) and has a medium-sized state space (2**96).

It claims that because it's a one-way stream cypher, that makes it
safe against chosen plaintext attacks.  That's not true.
Choose a plaintext of all zeros, and that gives you the
output of the chaotic system which you can analyze for patterns.
If you know the structure of the chaotic system, you can
analyze the mathematics to see how to find the state space,
and how to find the future output from the current output and
the state space - if the algorithm is strong, this is difficult,
but if the algorithm is weak, this is easy.  If you don't publish
the algorithm, nobody can prove that it's strong, and in the
world of cryptosystems, that means nobody will trust it,
because we know how weak many other strong-looking algorithms are.