lena.jpg

Hiding information in plain sight has allways been an interesting subject. I recently came across a paper, describing Hydan, that does this by exploiting the redundancy in the x86 instruction set. For example, any time you add 50 to a register, you can just as easily subtract -50 and get the same result. By alternating which method you choose, you can encode a 1 or 0 at a rate of 1 bit of encoded data per 110 bits of object code. It is a pretty interesting topic as there are many possible security applications for this and it’s generic enough to be applied to non-x86 instructions. There are, of course, easier ways to hide data. (Save the image above and open it with either unrar or winrar to see the instructions.)

( hydan.pdf )

 
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