An inscription found on the inside of an old fiddle has never been deciphered.


The Riverbanks Ripper was a serial murderer, who killed nine people in the 1970s. He was never identified. At one of the crime scenes he left behind an encrypted note that is unsolved to date.


Over 180 readers have commented on my recent blog articles about the Tengri 137 mystery. Now Tengri 137 has posted a new challenge.


In 1907 an encrypted postcard was sent from Box, UK, to nearby Chippenham. Can a reader decipher this note?


Blog reader Bart Wenmeckers has solved a 19th century cryptogram I recently introduced with Hill Climbing. A few diagrams he provided give me the chance to explain how this powerful technique works.


Today I’m going to report about an unsolved encrypted document created five centuries ago and now owned by the Beinecke Library in Connecticut. And no, I’m not talking about the Voynich manuscript.


My comic strip Chief Security Officer is getting more and more popular. Here are episodes 11 to 14.


The Beale cryptograms are the greatest hoax in crypto history. Generations of treasure hunters have tried to solve them and to find the hidden treasure, the location of which they allegedly describe. Nobody has ever been successfull, as the treasure simply does not exist.


A new Tengri 137 challenge has shown up. Blog reader Norbert Biermann found the solution – codebreaking at its best. Now the next Tengri 137 puzzle is waiting to be solved.


In one of his books British priest and novelist Sabine Baring-Gould (1834–1924) published a short cryptogram. Can a reader solve it?