On Mon, Jun 23, 1997 at 11:38:25PM -0700, Bill Stewart wrote:
That's the major problem with images, you need to generate your own. Unless you fancy writing an image enhancement system, and analyse the algorithms in existing systems to ensure that randomness is introduced. .. Or, set up your own webcam "to watch your coffee pot twice a minute" or something. Merge the crypto stream through the gifs after tweaking the brightness and contrast to avoid 0 and 255 (a light fixture with a pattern of 254/255 values gets suspicious, and is not from thermal noise - a "problem" with monochrome quickcams for night photography).
Pictures like coffee pots are likely to have parts that change (e.g. the state of the coffee pot) and parts that don't change (e.g. the part of the wall that isn't blocked by the pot.) This means that it's easy to tell which bits are being messed with, if somebody's watching successive pictures. If the digitization's random enough in the low bits, it's a bit better, but a picture of something moving helps. Oceans and fog are great....
Sources of pictures aren't really the problem, though -- it's developing the widespread habit of people sending references to pictures along with their email. For example, if the "cool thing to do" was to note a link to a favorite photo in your sig (as I have done, below), then people who were interested in communicating privately could build up a significant cache of shared pictures. Code to automatically compare pictures with the previous version, and decrypt the embedded messages is no big deal -- the big deal is getting people to habitually include links to pictures -- or sound files, or whatever... -- Kent Crispin "No reason to get excited", kent@songbird.com the thief he kindly spoke... PGP fingerprint: B1 8B 72 ED 55 21 5E 44 61 F4 58 0F 72 10 65 55 http://songbird.com/kent/pgp_key.html Picture of the day: http://songbird.com/pix/photos/gc8.jpg