Postcard-Nantes-bar

During World War II a woman from Loiret, France, sent an encrypted message to a recipient in Nantes, France. Can a reader break this cryptogram?

World-Record-Challenge-bar

The longest key ever publicly broken by exhaustive key search has 64 bits. A challenge I created a few years ago aims to improve this world record by one bit.

ADFGVX-Cryptograms-bar

ADFGVX is an encryption method used by the Germans in WW1. Some 20 ADFGVX radio messages from 1918 are still unsolved.

Isdal-bar

In 1970 the corpse of a woman was found near Bergen, Norway. In her car police found encrypted notes. These notes were deciphered, but the identity and the cause of death of this woman have remained a mystery until today. Thanks to blog reader Bjarne, I can now present a few new facts about this…

Koehler-cryptogram-bar

In 1944 a Nazi spy located in New York sent encrypted messages via Paris to Germany. These cryptograms have never been deciphered.

Passwords-16-bar

The list of most-frequently used passwords has changed little over the past few years. In 2016, “123456” once again was the most popular one.

LCS-35-board-bar

In 1999 cryptographer Ron Rivest published an encrypted text that was designed to take 35 years to break. 18 years later it is still unbroken.

Bigram-Porta-bar

Substituting letter pairs (bigrams) is an encryption method that was already known in the 16th century. Is it still secure today?

Goldbar-bar

Seven Chinese goldbars  from the 1930s bear encrypted inscriptions that have never been deciphered. The provenance of these goldbars is a mystery, too.

Cylob-50-bar

Today, I’m starting a new series on Klausis Krypto Kolumne. I’m going to present the 50 most important unsolved cryptograms. Number 50 is the Cylob cryptogram, a truly mysterious book.