Cipher Machine Challenges

Crypto homepage

The Challenges


A few years ago I created a cryptographic challenge that allows hobbyists to try to decrypt messages encrypted by the M-209 encryption machine. George Lasry won the challenge in early 2017.

This page presents other Challenges (but I left links on my M-209 Challenge). At this time, there are few problems. I will add more in the coming months.

My favorite subjects are the encryption machines used before or during the Second World War. There are several types of problems. The simplest requires only knowing well the machine used. Some problems are simple fun puzzles (I hope!). Others problems require knowledge of the known decryption methods. Finally few problems have no obvious solutions. Finding their solution can advance the cryptographic science. You can suggest problems too. Perhaps I will add them to my challenges.

If you want to participate to my Challenges you send me your solution for each problem by email. Please, put the following text in the subject line: "The name of the Cipher Machine - Solution - Problem Number". For example "Kryha - Solution - 2nd problem".

The first time you send me any solution, give me your name (or nickname) and your country.