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The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:16:10 ADT
Bill Stewart (bill.stewart@pobox.com)
Sun, 22 Mar 1998 12:37:27 -0800
John Young forwarded this to Cypherpunks; Rivest's paper is short and
interesting.
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The New York Times, March 22, 1998, p. 31.
New Method To Veil Data Could Upstage Export Policy
Cryptologists find a way to foil eavesdroppers without
secret codes.
By John Markoff
San Francisco, March 21 -- One of the nation's leading
computer scientists has proposed a novel technique for
scrambling data that could circumvent Government export
policies aimed at limiting the foreign sale of encryption
technology.
The technique, which was described this week in an Internet
discussion among computer researchers, was introduced by
Ronald L. Rivest, a computer scientist at the Massachusetts
Institute of Technology and one of the inventors of the
most widely used commercial encryption scheme, RSA.
The new approach, which is described in a short technical
paper that has been posted to Mr. Rivest's M.I.T. Web site
(http://theory.lcs.mit.edu/~rivest/chaffing.txt), is
described as "chaffing and winnowing" digital information
instead of encrypting it.
According to Mr. Rivest's paper, it is possible to hide a
message by breaking it into packets that are then secretly
identified as good information, or "wheat," and gibberish,
or "chaff," in such a way that an eavesdropper cannot
distinguish the two.
Because the individual packets would not be encrypted, Mr.
Rivest said, such a system would circumvent current export
restrictions.
The two principal ways of communicating in secret are
encryption and steganography. Steganography uses computer
techniques to embed a secret message in a document like a
digital image. In encryption, secret information is encoded
using functions that require difficult mathematical tasks
to decode, and it has become the standard way of
transmitting secret information electronically.
There are no restrictions on the domestic use of this
technology, but the Government has been trying to force the
industry to adopt standards that would permit
law-enforcement officials to have mathematical keys
allowing them to decode messages without the knowledge of
the sender or receiver. The Clinton Administration says the
standards are needed to fight crime and terrorism.
Opponents argue that the Government decoding keys, to be
stored in computers, could easily be stolen, compromising
privacy and the security of credit card numbers and other
personal information.
In terms of exports, with few exceptions the Government
limits the software to codes that can be easily broken.
"Winnowing does not employ encryption, and so does not have
a 'decryption key,' " Mr. Rivest wrote in his paper. "As
usual, the policy debate about regulating technology ends
up being obsoleted by technological innovations."
Peter Neumann, an SRI International computer scientist who
has read Mr. Rivest's paper, said that although "there is
still no certainty that this is a practical idea," if it
works, "it throws another clinker at the Justice
Department."
Other cryptography experts said they were uncertain whether
it would be possible to skirt Government export
restrictions in this way, but that the idea was an
impressive new approach that might have valuable commercial
applications.
"He's a very clever guy," said George Spix, a Microsoft
researcher who specializes in cryptography policy issues.
" It goes to show that for all the technological wizardry
in the world, there's nothing like an intellect."
One of the potential limitations of the new method is that
the total information transmitted might need to be hundreds
of times larger than the actual message.
Mr. Rivest said, however, that he had discussed the idea
with Adi Shamir, an Israeli cryptographer, and that Mr.
Shamir had proposed compression methods that would reduce
the total transmission to only about twice the actual
message size.
The strength of the idea for chaffing and winnowing is that
it is possible to prove mathematically that a message
cannot be decoded, Mr. Rivest said.
He said he had come up with the idea recently while
teaching an undergraduate computer course.
In addition to his role as associate director of the
Laboratory of Computer Science at M.I.T., Mr. Rivest is a
consultant and shareholder in RSA Data Security Inc., a
company that develops encryption software.
"I put the winnowing and chaffing idea out there to
stimulate debate,"' Mr. Rivest said. "I hope it will help
clear up some of the issues that have been raised in the
policy discussion.
[End]
Thanks!
Bill
Bill Stewart, bill.stewart@pobox.com
PGP Fingerprint D454 E202 CBC8 40BF 3C85 B884 0ABE 4639
The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:16:10 ADT