[Cryptography] Underhanded Crypto

[ianG]

http://underhandedcrypto.com/rules/

The Underhanded Crypto contest was inspired by the famous Underhanded C 
Contest, which is a contest for producing C programs that look correct, 
yet are flawed in some subtle way that makes them behave 
inappropriately. This is a great model for demonstrating how hard code 
review is, and how easy it is to slip in a backdoor even when smart 
people are paying attention.

We’d like to do the same for cryptography. We want to see if you can 
design a cryptosystem that looks secure to experts, yet is backdoored or 
vulnerable in a subtle barely-noticable way. Can you design an encrypted 
chat protocol that looks secure to everyone who reviews it, but in 
reality lets anyone who knows some fixed key decrypt the messages?

We’re also interested in clever ways to weaken existing crypto programs. 
Can you make a change to the OpenSSL library that looks like you’re 
improving the random number generator, but actually breaks it and makes 
it produce predictable output?

If either of those things sound interesting, then this is the contest 
for you.