Wednesday, November 01, 2006

A Steganography Scheme - Part 2

My text based steganography program is here! I completed the program yesterday, and Vanessa came up with a great name: Steganosaurus. Get in touch with me if you would like me to send you the program and the source code. I'm still considering publishing it on an open source hosting site.

You may recall my previous post about this steganography scheme, and I said I would tell you how it all works. So here goes:

My steganography program needs 4 pieces of information to embed or extract a secret message, it needs a file which will be converted, the base, the shift value, and a filename to which the converted message will be stored. The base and shift need a bit of explanation.

Base: All data on a computer is a number, and a number can be expressed multiple ways. I wrote about this in "A Steganography Scheme - Part 1". So the base tells Steganosaurus how to express the data. Should each number in the source file be converted into a series of values between 0-10, 0-50, 0-200? The choice is yours.

Shift: My program outputs a range of values from the source file, and each of them is between 0 and Base. How does this become readable text? That is the purpose of the shift, it is a value added to each piece of the converted file to make it into a character. So the result of the whole process is the contents of the original file expressed as numbers in the range Shift to Base + Shift. These numbers are converted into Unicode characters (UTF-8) so the end result is a readable file. You can see an example in my wiki entry about Steganosaurus. (It's probably easiest to see an example.) By using different shift values, you can hide the data from your original file in text from any language in the world.

So check it out, give it a shot, and ask me to send Steganosaurus to you.
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