Puzzles
Interactive cryptography puzzles that teach by doing: how do Alice and Bob send a treasure through a thieving postman?
These puzzles teach real cryptography by letting you break it. Your browser checks each answer against a hash, so nothing is sent anywhere and the page source doesn't hold the answers.
Puzzle series
- The treasure chest puzzleAlice has to send Bob a treasure through a thieving postman, with no key ever travelling. Six levels, from padlocks to discrete logarithms.
- The Cipher Ladder: 15 cipher puzzlesFifteen levels from a Caesar shift to Enigma, an unsalted hash and a real sealed cipher.ink message. Every one runs in your browser.
- The Prime Hunt: eight prime number puzzlesEight puzzles with one numeric answer each: a mirror prime, an emirp, a chain, a number that fools Fermat, a hidden prime and more.