2011 Shmoocon CTF Warmup Results

The 2011 Shmoocon Ghost In The Shellcode CTF warmup event went well this weekend. There were three challenges: an image puzzle riddle thing, a cryptography challenge, and an exploit challenge. See for yourself at http://ghostintheshellcode.com/2011/.

Unfortunately the crypto one fell faster than I expected and ended up being the easiest challenge of the three! LarsH and kaliman submitted a solution in just 28 minutes! From the chat, I gathered that people solved it in three ways:

1. typing the equations into wolfram alpha (this tool is becoming very popular! see recent solutions by tamaroth at crackmes.de among others)
2. using the Chinese remainder theorem (intended method)
3. using the method of successive substitution

I've never seen the third method until now! Can there exist systems where CRT fails but this method finds a solution?

The third challenge ended up being really really interesting and apparently the hardest. Awesie, the only solver and winner of the warmup and Shmoocon barcode, graciously details his methods for the public: http://ppp.cylab.cmu.edu/wordpress/?p=410. Congratulations awesie!