Geheimschreiber-bar

The Siemens & Halske Geheimschreiber (T-52) was the second-most im portant encryption machine of the Germans in World War II. George Lasry has recently published a few computer-based attacks on this device.

Rubik

A Rubik’s Cube can be used to define a crypto system that cannot be broken with quantum computers. Here’s a puzzle that shows the concept this system is built on. Can you solve it?

Georgstaler-bar

Here’s a strange cipher device: the front-side is a medal depicting St. George fighting a dragon, the rear-side is a cipher disk. Does a reader know anything about the background of this item?

Fact-or-Fiction-bar

Three encrypted newspaper advertisements from 1879 are still unsolved. Can you decipher them?

Stamp-album-moon-bar

An evelope found in a stamp album contains two encrypted messages. Can a reader solve them?

Rohonc-Codex-bar

The Rohonc Codex is one of the most famous cryptograms in the world. But is it still an unsolved one? That’s difficult to say.

Alster-Bottlepost-Cryptogram-6b-bar

A sixth encrypted bottle post has been found in the river Alster in Hamburg. Still, nobody seems to have a clue what these strange messages mean.

Henri-Cipher-bar

A French museum has an unusual cipher device on display. Can my readers find out how it works?

Schmidt-cryptograms-bar

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.

Elgar-Liszt-bar

The Dorabella cryptogram, an encrypted message left behind by British composer Edward Elgar, is one of the most famous crypto mysteries in the world. Here are two more crypto mysteries Elgar created. They have not received much attention so far.