Yellow-dots-bar

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.

Starlight-Steganogram-bar

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

Friedman-Music-bar

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

Friedman-Bacon-Castle-bar

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.

Music-bar

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?

Chess-2-bar

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

Chess-2-bar

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

Bacon-bar

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

Censorship-Fashion-bar

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.

Christie-Stamps-bar

The British mail authority has issued a set of six stamps devoted to crime writer Agatha Christie. The stamps are packed with steganographic messages. Can you find them?