plaidCTF 2014 - tiffany (re300)

For PlaidCTF2014, Eindbazen and fail0verflow joined forces as 0xffa, the Final Fail Alliance.
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Reversing (300 pts)
We want to get access to a server used by The Plague. Maybe if you
can find out what key is accepted by this binary you can find out
where or when The Plague is...

Yay, a Linux x86_64 executable! Let’s run it and see what happens, because what could possibly go wrong when running a random binary off the internet?

$ ./tiffany
This may take a while...
Please enter a string: TEST
Sorry, wrong.

Well, that took 3 seconds to initialize and 5 seconds per input string character. Sure seems to be doing a lot of stuff. Let’s load it into IDA to get a general idea.