The DefCon 16 Mystery Challenge

Hackers like nothing more than solving complex problems. One of the most difficult contests at DefCon, is known as the Mystery Challenge. Teams compete to solve a series of riddles and cryptographic challenges in order to win respect as well as a black badge, granting them DefCon admission for life.

The Mystery Challenge started out months before DefCon with the contest organizer, Lost leaking hints on the DefCon forums. Once DefCon began, competing teams were given an envelope containing a riddle. After solving the riddle they were presented with a book full of cryptographic challenges. All the solutions equaled "X marks the spot."

In order for the teams to move forward they had to dig underneath the ex libris, the nameplate on the inside front-cover of their crypto book. Hidden under the ex librs was a 2GB SD card filled with source code and more crypto secrets.