An encrypted postcard I recently discovered looked familiar to me. As it turned out, I had already blogged about a card from the same sender.

In the early 20th century, a young man sent encrypted postcards to his spouse. Can a reader decipher these?

The German punk-rock band “Die Ärzte” has announced a new album. The song titles are currently published in an encrypted way.

Charles Dellschau (1830-1923), a US outsider artist, left behind fascinating paintings and numerous ciphertexts. Can my readers help me to decrypt these?

In the preview of the new Batman movie, a ciphertext can be seen. Can a reader solve it?

I need the help of my readers to correctly decipher two encrypted newspaper ads from 1882.

The inscription on the Goldenes Dachl ( Golden Roof) in Innsbruck, Austria, is one of the oldest unsolved crypto mysteries known to exist. According to press reports, the cipher has now been broken.

Forrest Fenn’s hidden treasure attracted puzzle fans from all over the world. Now, three months after the end of the hunt, Fenn has passed away.

A cryptogram found in the computer game “Call of Duty Zombies” has baffled codebreakers for four years. Can a reader finally solve this challenge?

Numerous steganographic methods have been used by prisoners of war to hide messages in letters to their families. Here’s one I didn’t know before.