Here are two cryptograms that are easy to solve: a postcard sent from Dortmund, Germany, in September 1900 and another one sent from the same place a few weeks later.

Today I’m presenting a 24 letter message that has been encrypted with a Playfair cipher. Such a short Playfair cryptogram has never been solved before.

The 1980s rock band Arcadia published a few encrypted messages on their record covers and in a sheet music book. The solutions are not known to me.

The autokey cipher is a variant of the Vigenère cipher that was once considered unbreakable. With today’s means it can be deciphered. Can a reader solve the challenge I’m introducing today?

The Voynich manuscript was covered in the latest episode of the German documentary TV series “Terra X”.

Cryptocurrency platform Phemex has published a picture puzzle with a 2.1 bitcoin price for whoever provides the solution.

An engineer who deceased a few years ago has left behind an unusual painting. Does it contain a message encoded in a binary code?

HistoCrypt 2020 will take place from June 15-17, 2020 in Budapest, Hungary. The Call for Papers is running until February 2.

The Zodiac Killer murdered five or more people and sent four encrypted messages to newspapers. The case and three of the cryptograms have never been solved.

Gerry Haynaly has deciphered the encrypted diary I recently introduced. Here’s how he did it.