Christopher Columbus frequently used a signature that included seven letters not belonging to his name. Do they represent an abbreviation?

At the hacker conference 44CON 2019, wich took place in September in London, I gave a talk about Cold War cryptography. Here’s a professionally produced video of it.

Sometimes, deciphering a cryptogram is easier than reading the deciphered message. Here are two plaintexts I have difficulties to understand.

In the end credits of the 2010 movie “Fair Game” some letters are marked. Do they spell out an encrypted message? Nine years after the release of the film, this question is still unanswered.

I’m looking forward to HistoCrypt 2019 (June 23-26 in Mons, Belgium). Among the speakers are many readers of this blog.

My readers have shown that a Playfair cryptogram consisting of only 50 letters can be broken. Here’s a Playfair challenge with only 40 letters. Can you break it, too?

The four cryptograms contained in a book partially written by famous German author Arno Schmidt are among the most interesting I have seen recently. My readers have provided some additional information about them.

The hijacking of a Boeing 727 aircraft in 1971 is considered one of the most spectacular crimes in the history of the USA. After the hijacker had left the plane with a parachute, he was never seen again. According to a recent newspaper article, a deciphered cryptogram might now solve this mysterious case.

18-year-old chemistry student Paul Rubin was found dead with a cyanide poisoning in 1953. In his possession police found an encrypted message. This cryptogram has never been deciphered.

English actress Diana Dors left behind an encrypted message. This cryptogram allegedly leads to two million pounds.