In 1877, US engineer Frank S. Baldwin received a patent for a cipher disk. Blog reader Matthias Brüstle has encrypted two plaintexts with this method. Can a reader break these?

In an online forum, two encrypted postcards from 1911 have been posted. Can a reader solve them?

For years, my readers and I have been wondering what’s behind the Cylob cryptogram, a printed booklet that contains strange symbols. Now I have learned about a similar work. The author of it is known.

An imprisoned murder suspect has tried to send an encrypted message to a friend. Can my readers help to break this ciphertext?

In a 1932 police journal, an unsolved encrypted message is depicted. Can a reader solve it after nine decades?

Here’s an encrypted postcard from the late 19th century. Can a reader decipher it?

The HistoCrypt 2021 is scheduled for September 20-22 in Amsterdam. The Call for Papers is running until February 21. Let’s hope that the Covid-19 situation has improved by then.

Here are two sequences of letters or symbols that look like encrypted messages, but are not. Can you guess what their real meaning is?

Marie Vahjen (1880-?) from New York was one of the few women who filed a patent for an encryption device.

In 1912, a young woman living in Winchester near Southampton received three postcards encrypted in a pigpen variant. Can a reader decipher these?