German mathematician Dr. Heinrich Döring was one of the most brilliant codebreakers of the Second World War. Does a reader know what happened to him after 1945?

The encrypted altar inscriptions of Moustier, Belgium, have been puzzling codebreakers for 170 years.

Yesterday I visited the exhibition “Top Secret!” in Mons, Belgium, together with a few friends and blog readers. Apart from many fascinating exhibits, three interesting photographs of rare cipher machines caught my attention. Can my readers say something about the background of these devices?

The NSA Symposium on Cryptologic History 2017 featured a number of very interesting presentations. Here are videos of a few of them. In addition, I will introduce three crypto puzzles I encountered at the symposium.

In various parts of London and in many other English cities kerbstones bear enigmatic markings. This kerbstone code has yet to be deciphered.