The Codex Seraphinianus is an unusual book, a beautiful artwork, and an unsolved crypto mystery. It’s the Voynich Manuscript of the 20th century.


US military technician Brian Regan was sentenced to life in prison, after he had tried to sell secret information to foreign governments. He used a few interesting ciphers.


This is the shortest cryptogram I have ever introduced on this blog: 46, 9, 4-57, 3, 5. Can a reader decipher it?


A new internet mystery game, named “Red Triangle”, has surfaced. Meanwhile, six chapters with crypto puzzles and other challenges are known to exist. Is the Red Triangle the new Cicada 3301?


A few years after the Zodiac murders, an unknown person sent a letter to an address in Albany, NY, claiming that he was the Zodiac Killer and that he intended to start killing again. A few lines of this letter are encrypted. The cleartext is unknown.


During the Second World War, an unknown person stuck sheets with seemingly random letter sequences into a book. The meaning of these letters is unknown.


In the 2006 British-American mystery thriller “The Prestige” a stage magician keeps an encrypted  journal. Some passages of it can be seen in the movie. Is it possible to decipher them?


Edgar Allan Poe once asked the readers of a magazine to send him encrypted messages. He could break all of them, except two.


US standardization authority NIST has published the algorithms that participate in the Post-Quantum Crypto Competition. No fewer than 69 crypto systems enter the race.


A Reddit user has found an encrypted message written in a dictionary. Can a reader break this cryptogram?