->calling attention to the message BECAUSE it is encrypted? "If he went to ->the trouble of coding it, there MUST be something in there!!" Granted that ->if everyone begins encrypting, this problem will vanish... are there ->practical solutions in the meantime? (eg, Codes that look like plaintext?) a good point indeed. I know of no software that works the way it seems you would like. The best would be encryption software that makes your 'secret' message look like the kind of message that you would actually be sending to the recipient. Some kind of message that (when read by a human) makes sense, and seems innocuous. This sounds like a VERY difficult problem, and one that is not likely to be solved any time soon (in the sense of having this be done 100% by software). Another option would be to have the message fit the letter-frequency, letter-pair frequency, etc... that 'normal' messages have. The idea here is that messages may be scanned for unusual (i.e. non-english text) properties in this regard, and then scanned further by humans and/or computers in the order of their 'interestingness'. So to defeat this kind of scanning, your 'secret' message should 'appear' to be a 'ordinary' message. -- Edward A. Bertsch (eab@msc.edu) Minnesota Supercomputer Center, Inc. Operations/User Services 1200 Washington Avenue South (612) 626-1888 work Minneapolis, Minnesota 55415 (612) 645-0168 voice mail

Peter Breton writes:

In using encrypted communications, how does one avoid the problem of calling attention to the message BECAUSE it is encrypted? "If he went to the trouble of coding it, there MUST be something in there!!" Granted that if everyone begins encrypting, this problem will vanish... are there practical solutions in the meantime? (eg, Codes that look like plaintext?)

The study of how to hide the _existence_ of an encrypted message is called _steganography_. Messages have traditionally been: -placed on microdots and hidden inside letters, under stamps, etc. -transformed into innocuous-looking messages ("Hello, Peter! Things are going very well on this January morn.")...typically used with book codes -deposited in physical "dead drops," such as in tin cans by the side of the road, in the branches of trees, etc. (all agreed-upon in advance, of course) The cypherspace domain offers new degrees of freedom for hiding such messages: -messages may be packed into the "least signficant bits" (LSBs) of digital images, GIFs and TIFFs, sound samples, etc. As these bits are at the "noise floor" for modern recording technology, message bits can be easily made indistinguishable from "real" bits. A simple GIF image, such as those posted worldwide in the various "pictures" groups, can easily hold 50K bytes or more just in the LSBs (of each of the colors). A standard 2-hour digital audio tape (DAT) can carry 80 M bytes in the LSBs alone! (Imagine the Customs Department trying to stop someone from carrying out the blueprints to the Aurora spy plane packed into the LSBs of their favorite tape!) -similar systems can be used to pack bits into the "ragged right" margins of messages like this one, where the precise word spacing carries some bits. Not very many, of course. And the spacing is susceptable to munging. -raw data, such as weather reports and sports scores, can be used. Used since the dawn of espionage, and featured as a plot device in the French thriller "Soft War," this method is certainly still possible to use. As the amount of bits moving around increases dramatically, so, too, will the avenues for sending encrypted messages. -Tim May -- .......................................................................... Timothy C. May | Crypto Anarchy: encryption, digital money, tcmay@netcom.com | anonymous networks, digital pseudonyms, zero 408-688-5409 | knowledge, reputations, information markets, W.A.S.T.E.: Aptos, CA | black markets, collapse of governments. Higher Power: 2^756839 | PGP Public Key: by arrangement.