In a British censorship manual from WW2 two pictures containing hidden messages are displayed. Many have tried to find these messages, but up until now with no success.


Many color laser printers add tiny yellow dots to each page they print. These dots encode a timestamp, the printer serial number and potentially additional information. Although these dot codes have been around for at least 25 years, not much is publicly known about them.


The last crypto challenge I’m going present in 2016 was created by master-codebreaker Tony Gaffney. Can you solve his starlight steganogram?


Forget about all the Christmas carols! Here comes the Friedman’s musical cryptogram from 1933, as played by a scorewriter.


William Friedman, one of the most notable cryptologists in history, used a 16th century stegnography system to hide messages in pictures. Some of his codes are hard to decrypt. Maybe a reader can help.


17th century polymath Daniel Schwenter invented a secret writing method based on musical notes. Can a reader solve a musical cryptogram encrypted in this system?


While in New York Carlsen and Karyakin are playing their final games, I am going to present three (alleged) secret codes related to chess.


In World War 1 a female spy in France used a chess board and chess pieces to code a secret message.


Two texts in a book written by Renaissance genius Francis Bacon contain hidden messages. Can a reader find them?


A British censorship manual from WW2 introduces a wide range of message hiding techniques. Some of the examples given are hard to comprehend. Maybe my readers can help.