A sixth encrypted bottle post has been found in the river Alster in Hamburg. Still, nobody seems to have a clue what these strange messages mean.


A French museum has an unusual cipher device on display. Can my readers find out how it works?


The four cryptograms contained in a book partially written by famous German author Arno Schmidt are among the most interesting I have seen recently. My readers have provided some additional information about them.


The Dorabella cryptogram, an encrypted message left behind by British composer Edward Elgar, is one of the most famous crypto mysteries in the world. Here are two more crypto mysteries Elgar created. They have not received much attention so far.


Here’s a postcard that was sent from the Isle of Wight to London in 1905. Can a reader decipher it?


A workshop at HistoCrypt was dedicated to codes and nomenclators – for centuries the most popular kind of encryption. One of the topics discussed was a consistent terminology. Here is my suggestion. Perhaps, my readers can help to improve it.


The movie “Wanted” (starring Angelina Jolie and Morgan Freeman) contains a steganographic message. Can a reader decipher it?


Last year I reported on an encrypted inscription on a cigaret case from 1909. Though it looks like a simple substitution cryptogram that can be broken without much effort, it is still unsolved.


At the HistoCrypt 2018 I presented a poster about an analysis of the Dorabella Cryptogram. Here are the details of this work.


Many color laser printers add tiny yellow dots to each page they print. These dots encode the printer serial number and additional information. A recently published research paper reveals new information about this secret code.