German adventurer and explorer Philip von Hutten (1505-1546) left behind an encrypted note that has never been deciphered. Can a reader of this blog solve this mystery?


Here are a few more encrypted texts Peter Nüchterlein, the writer-in-residence in Wernigerode, Germany, has found in a Vienna archive. Can a reader decipher them?


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.


Designing a secure manual encryption algorithm is a challenge. Some cryptographers have developed ciphers that require a deck of playing cards. The best-known one of this kind is Bruce Schneier’s Solitaire. Today, I am going to introduce another one: Talon by Aaron Toponce.


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?