20 years ago, Jim Gillogly, a great codebreaker and reader of this blog, created three crypto challenges – a Playfair, a Double Playfair, and a Double Column Transposition. Can you solve them?

Three months ago, I presented a terminology for codes and nomenclators, based on a workshop that took place at the HistoCrypt conference. After having received some interesting feedback, I can now provide an update.

A message written 118 years ago in Aldino, Maryland, waits to be solved. Can you break this cryptogram?

The Vernam cipher is mentioned in dozens of cryptography books. It is simple and more secure than most other basic encryption methods. Can you solve the three Vernam challenges I am going to introduce today?

An advertisment poster an Instagram user has seen in a New York subway is completely encrypted. Can you decipher it? And can you tell me what is behind the “spiritual consultancy” that has published this poster and a few others?