A children’s book from the 1980s contains numerous encrypted and hidden messages. Can a reader solve four of these?

On Cocos Island in the eastern Pacific, a “treasure” consisting of works created by 40 modern artists is buried. The exact location is described in an encrypted message. To my knowlege, this cryptogram has never been published.

In 1891, an unknown person published an advertisement in the Morning Post. Five words in this message are encrypted. Can a reader break this cryptogram?

At the “Secret Communications 3” exhibition in Duivendrecht, NL, blog reader Karsten Hansky showed me a wired rotor similar to the ones used by the Enigma. It is probably of Russian origin. Does a reader know more about it?

Today I’m presenting a 26 letter message that has been encrypted with a Playfair cipher. To my knowledge, such a short Playfair cryptogram has never been solved before.

Crypto expert Frode Weierud has published a collection of unsolved cryptograms from 1969. If you’re looking for a challenging codebreaking project, here you go.

IT security experts have cracked a number of passwords used by Unix pioneers in the late 1970s.

In 1916, the USA bought the West Indian islands from Denmark. An encrypted telegram about this purchase, sent by the Danish ambassador, is available on a website.

Magnus Ekhall from Sweden has solved my Playfair challenge from September 2019. With only 28 letters, this ciphertext is the shortest of its kind ever broken.

My users ure usually very successful when it comes to breaking encrypted postcards. Anyway, the one I’m going to introduce today might be a tough challenge.