Which of the following is the cleartext? 1. Bit and byte dropout can significantly impede communication. 2. Flower and shrub planting can greatly enhance landscaping. 3. Word and phrase substitution can hopelessly disguise meaning. 4. UFO and space-alien belief can seriously damage credibility. If you *presume* my context, you easily identify (3). If only the wordlists that translate between (1), (2) and (4) were available for your inspection, you would be up the creek but you wouldn't know it. Yes, this is aba's "exxon" at work again, and yes, it seems to me that deniability through other-plausible-meaning is viable as a form of stego. Grammatical correctness is easy to maintain, and care in choosing words can preserve much apparent meaning. Bolivar
This class of code is fairly old. In 'The Codebreakers' an incident is recounted (I think from WW2). A suspected spy in the US was sent a cable from overseas, reading 'Our father is dead'. This was intercepted, and the censors, suspecting a stego'd message, substituted 'Our father is deceased'. The suspected spy immediatly sent back 'Is father dead or deceased?', and was arrested. The book contains many fascinating stories of stego and attempted stego, including mailed knitting patterns, crossword puzzles, drawings, sports statistics, etc. On the eve of Pearl Harbour, the wife of a Japanese diplomat in Oahu sent a long message to Japan describing in detail the many kinds of flowers blooming at that time in Hawaii. It was sent through non-diplomatic channels, and authorities suspecting it contained stego, failed to deliver it. After the war it came out that she did regular gardening columns for a Japanese magazine, and the message was entirely innocent. Peter Trei Senior Software Engineer Purveyor Development Team Process Software Corporation trei@process.com