To help flog the second edition of Disappearing Cryptography and
encourage a general education in things steganographic, I'm
continuing to roll out Java applets on the book's website.
This week I've added a few new features to last week's applet that
let you hide information in the noise of an image. That is, replace
the least significant bits of an image with either an ASCII text
message or random data. You can replace anywhere between 1 to all 8
of the image's bit plane. I think it's amazing how much you can stuff
in an image before it starts to degrade.
The new features allow you to examine the least significant bits of
an image. One option will delete the seven most significant bit
planes and keep only the least. Another option lets you compare the
most significant with the least, although it depends a great deal on
the image.
This experiment has its problems. Video cards don't always offer
enough precision. You'll get more consistent results if you use a
higher setting on your video card. The JPEG images don't have enough
resolution. Also, this system relies upon 24-bit color, a file format
that's rarely found in nature. More sophisticated systems can target
compressed images.
Try it here:
http://www.wayner.org/books/discrypt2/bitlevel.php
You can try earlier applets like this one for hiding information in
the order of a list of items:
http://www.wayner.org/books/discrypt2/sorted.php
Or this one for hiding in the voice over to a baseball game:
http://www.wayner.org/texts/mimic/
Source code protected by the GPL available for all of these. Just ask.
You might also be interested in my other new book, Translucent
Databases, for people who must guard sensitive information in their
database:
http://www.wayner.org/books/td/
