Reverse engineering CRC?

[Aahz]

It turned out to be a very standard CRC algorithm, complicated
by the presence of a few extra bytes of data being checked that
didn't appear explicitly in the file anywhere.

In the process I developed some very general techniques for
solving this kind of problem, which I've written about here
if anyone's interested:

http://www.cosc.canterbury.ac.nz/greg.ewing/essays/CRC-Reverse-Engineering.html

Excellent essay!
--
Aahz ([email protected]) <*> http://www.pythoncraft.com/

"Many customs in this life persist because they ease friction and promote
productivity as a result of universal agreement, and whether they are
precisely the optimal choices is much less important." --Henry Spencer