Last week, during USENIX’s first Enigma conference, EFF hosted a small Capture the Flag hacking competition. I designed one of the challenges myself, entitled Usable Crypto. It requires you to use PGP as an attacker rather than a defender. It’s on the easy side, as far as CTF challenges go, and I think many people who have absolutely no hacking skills but some fumbling-around-with-PGP skills could beat it without too much trouble. And it might even demonstrate why verifying fingerprints really is rather important.
If you’d like to give it a go, it’s live at https://usable-crypto.ctf.micahflee.com/. The plot for Enigma’s CTF was loosely based off of Cory Doctorow’s novel Little Brother. You’re an X-NET hacker fighting the surveillance state’s Department of National Security. You win when you capture the flag, which is a string of text that starts with “FLAG_” (but please don’t post it in the comments).