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.

After the First World War, Italian engineer Luigi Nicoletti invented a transposition cipher tool. Can you break a ciphertext I created with this device?

Two online games for crypto enthusiasts have been launched – one in Germany, one in Poland.

Blog reader Karsten Hansky has provided me a nice encrypted postcard from 1954. Can a reader decipher it?

George Lasry has found an interesting collection of challenge ciphers, probably used to train codebreakers during the early Cold War. Today, I’m going to present one of these challenges.