In the last decade of the 19th century, an unknown person sent three encrypted messages from a place named Bristol. Can a reader decipher these messages?


My readers are pretty good at solving encrypted postcards. However, the two specimens I am going to introduce today look pretty hard to decipher, as the messages are pretty short.


Montecrypto, a new online game that started yesterday, appears to be a mixture between Cicada 3301, Mystery Twister C3, escape room, and the Forest Fenn treasure hunt.


The Enigma breaking machine “Bombe” had a considerable impact on the course of the Second World War. A recently started crowdfunding campaign aims to create a new Bombe display area in Bletchley Park.


The challenges of Giouan Battista Bellaso were one of the top unsolved crypto mysteries. Norbert Biermann has now published the last two parts of the solution.


The M-138 is a low-tech cipher device from the first half of the 20th century. Though being quite simple, the M-138 is hard to break.


In the Second World War, the Germans constructed a voice encryption machine. I have only very little information about this device. Can my readers help me to find out more?


Among the most popular stories in cryptology are those about a hidden treasure, the location of which is described in an encrypted text. Here are three more stories of this kind.


According to a legend, an encrypted message was found in a cave of the Untersberg, a mountain in the Northern Alps. The cleartext is not known.


Encrypted newspaper advertisements were very popular in the 19th century. The ones I am going to introduce today are much younger. They were published in the 1980s.