Re: Figuring out table based encryption in assembly

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jonathon wrote:
> I've been tracing an old (1996) utility that uses a very sophisticated
> encryption algorithm for license info. It generates a table, uses
> constantly changing keys, and does some really bizarre stuff with
> multiplication, shifts, xor, and table lookups.
>
> The crypto group doesn't seem to be very active or very helpful, so I
> thought I'd ask here: is there any way to figure out if this is a
> standard encryption method?
>
> It's so complex, it seems unlikely some guy in his garage made it up.
> But at the same time, I'm not sure how to tell if it is DES, Blowfish,
> or something similar.
>

Greetings,
If you can isolate the encryption code and move it into an executable
which can run the encryption and nothing else, you could try browsing
the internet for the specifications for the different algorithms. These
specifications will generally contain test vectors; just put the test
vectors into the unknown algorithm and see if the output matches.

Chris
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.

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