The homophonic Polybius is a simple but hard to break manual cipher. Can a reader break a message I have encrypted in this scheme?
A cipher disk introduced on Reddit looks like a mass-produced item from the 20th century. Does a reader have any information about this crypto tool?
Here’s an telegram from 1952 that might have been encrypted in a code. Can a reader find out which codebook has been used and decipher the message?
The cover of a well-known cryptography book shows a 16-letter cryptogram. Its solution is unknown.
An encrypted diary posted on Reddit last year is still unsolved.
About a century ago, a young man from Austria wrote an encrypted postcard with a sad motive to his lover. Can a reader decipher this cryptogram?
Gravestones bearing an encrypted or hidden message are rare, and they have a morbid charm. On Reddit, I have found one I hadn’t known before. I have no idea where it is located and what the inscription means.
In 1888, an encrypted advertisement was published in the “Daily Chronicle”. Can a reader decipher it?
Here’s another cryptogram that can be seen in a TV series. Can a reader break it?
David Oranchak, a leading expert on the cryptograms of the Zodiac Killer, has published a video. It’s a must-see for everybody interested in this case.