Cryptris is a game proposed by Inria and developed by Digital Cuisine, with the support of Cap'Maths, and proposed under an open license.
The goal of this game is to show the interest of so-called asymmetric cryptography. In a series of puzzles, the player decrypts a message using a private key, while the computer tries to decrypt the same message using a public key.
The difficulty for the player increases linearly, while the computer will have more and more trouble. Cryptography protects your data effectively!