There’s a secret here….

Your players find a series of numbers on a wall in a dungeon. They know these numbers hold a message to reach the lich’s tomb below, but the method to reveal this message is hidden in one of the books in the lich’s library. A riddle reveals which book is the right one, but a wrong answer leads only to disintegration. Although a couple of successful rolls could lead the heroes to decrypt your Book cipher, your players might have more fun untangling this mystery themselves.

Ciphers are an algorithmic way to encrypt a hidden message with the intent that only the intended recipient is able to understand the message. Ciphers are perfect to create puzzles to challenge your players and can be seeded across multiple sessions as an ongoing mystery. Here I’ve collected four ciphers and the steps to use them, with each cipher being incrementally more difficult to decrypt than the last.

Contents

• Null cipher
• Symbol cipher
• Book cipher
• Grandpré cipher