In the 1950s, a US company published weekly newspaper advertisements that included crypto puzzles. Here are three of these.

Two months ago, US book author A.J. Jacobs showed me the encrypted journal of psychologist Abraham Maslow (1908-1970). My readers did a good job in analyzing this cryptogram. Now, A.J. asks for additional help.

In 1943, the British intecepted an encrypted radio message sent from an airplane. Can a reader decipher it?

British WW2 soldier and prisoner of war Donald Hill kept a steganographic diary. A 13-minute TV documentary available on YouTube tells this story.

In 1908, an ecrypted postcard signed with “Somebody” was sent to a sobriety organisation in Northern Ireland. Can a reader decipher it?

Blog reader Christoph Tenzer has sent me a nice crypto challenge, based on an enhanced Caesar cipher. Can a reader solve it?

A sword showcased in a Havana, Cuba museum bears an encrypted inscription. Can a reader decipher it?

The homophonic Polybius is a simple but hard to break manual cipher. Can a reader break a message I have encrypted in this scheme?

A cipher disk introduced on Reddit looks like a mass-produced item from the 20th century. Does a reader have any information about this crypto tool?