Scottish poet Thomas Urquhart (1611-1660) left behind two unsolved cryptograms. Along with many others, they are listed on a website maintained by Eugen Antal.

In 1931, a woman from Bonn, Germany, received an encrypted postcard from Switzerland. Can a reader break this cryptogram?

The “Playfair for Three” is a manual cipher that works similar as the Playfair, but is based on trigraphs instead of digraphs. Can you solve a challenge cryptogram that has been made with this method? 

Substituting letter pairs (also known as bigrams or digraphs) is an encryption method invented in the 16th century. Can you break a new challenge I have made?

In March, I blogged about a TV documentary about the Kryptos sculture produced by CNN. It has now aired and is available on Youtube.

Blog reader Eugen Antal has found a beautiful chronogram in a Slovak archive. Can a reader decode it?

In the 19th century, a series of over 40 encrypted ads was published in a British newspaper. Can a reader decipher them?

Fort Meade, a United States Army installation known as the home of the NSA, has launched a new logo, which bears an encrypted message. Can a reader decipher it?

An encrypted message from the Secret Archives of the Vatican has now been published on MysteryTwister C3. Can a reader solve it?

Camino de Santiago hiker Jens Grabarske has made me aware of an encrypted inscription in northern Spain. Can reader decipher it?