wonderer wrote:
Is there any published work on hiding subliminal messages in pictures? It seems like that would be really easy.
Someone did write a program which embeds information in a JPEG, but I don't have any other info (like where to get it, who wrote it, etc. :-) Actually though, embedding a message in a picture leans toward steganography. Subliminal channels, covert channels, and steganography are related to one another, and seem to overlap. I don't have precise definitions (does anybody else?). From reading, here is what I think these three methods are: Covert channel: you and I agree that if I mail you a letter with the stamp affixed sideways, that messageA is communicated. Or, we agree that a post sent to alt.test with the subject "el mariachi" conveys messageA. Or that my running a process and killing before 9:30 p.m. conveys messageA. Subliminal channel: you and I share a secret and convey our message in the digital signature of innocent message we pass to one another. Steganography: I write an innocent message, and I change the spacing between words, to convey messageA. Or, I embed the message in the low order bits of a picture or a sound file. So, it looks like that in subliminal channels and steganography, the actual message is passed, while covert channels don't (it's like winking at a friend - no message but lots of information). Also, it seems that steganography alters the innocent message itself, while a subliminal channel doesn't. Obviously, there is great room for hair-splitting. These are the differences as I understand them! Any other input? -- Karl L. Barrus: klbarrus@owlnet.rice.edu keyID: 5AD633 hash: D1 59 9D 48 72 E9 19 D5 3D F3 93 7E 81 B5 CC 32 "One man's mnemonic is another man's cryptography" - my compilers prof discussing file naming in public directories