British WW2 soldier and prisoner of war Donald Hill kept a steganographic diary. A 13-minute TV documentary available on YouTube tells this story.
In 1908, an ecrypted postcard signed with “Somebody” was sent to a sobriety organisation in Northern Ireland. Can a reader decipher it?
Blog reader Christoph Tenzer has sent me a nice crypto challenge, based on an enhanced Caesar cipher. Can a reader solve it?
A sword showcased in a Havana, Cuba museum bears an encrypted inscription. Can a reader decipher it?
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?
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