Italian crypto history expert Paolo Bonavoglia has forwarded me a 19th century shorthand note from Italy. Can a reader decipher it?


Two years ago, I blogged about five encrypted 19th century newspaper ads that contain Bible references. Blog reader Thomas Ernst found an interesting solution approach, but so far nobody has deciphered these cryptograms.


Peter Nüchterlein, the writer-in-residence in Wernigerode, Germany, has asked me for help. In a Vienna archive he has found over 100 encrypted documents from the Thirty Years’ War. Today, I am going to introduce five of them. Can a reader decipher them?


Can you decipher this encrypted graffiti that was found near Rome, Italy? The encryption method used looks like a Pigpen variant.


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?


Can a reader decipher this encrypted diary page I found on the internet? I don’t know by whom and when it was written, but I’m sure that it can be solved.


A Reddit user has posted an encrypted note he found in a family member’s personal effects. The cleartext is not known. Can you solve it?


Stephen Hawking, the world-famous physicist who died earlier this year, has left behind ten puzzles. One of these has now been published. It looks like a cryptogram.