Klaus Schmeh

Klaus Schmeh ist Experte für historische Verschlüsselungstechnik. Seine Bücher "Nicht zu knacken" (über die zehn größten ungelösten Verschlüsselungsrätsel) und "Codeknacker gegen Codemacher" (über die Geschichte der Verschlüsselungstechnik) sind Standardwerke. In "Klausis Krypto Kolumne" schreibt er über sein Lieblingsthema.

According to a Reddit post, a needlework made in the 1980s contains a hidden message. The details are not known any more. Can you find this message?

From 1884-1887 a series of 25 encrypted newspaper advertisements was published in the “Daily Telegraph”. The key is known. Can you help me to decrypt these messages?

Four years ago I blogged about an encrypted (?) text a blog reader had found in an old school book. It is still unsolved. Meanwhile I have better scans and some additional information.

On Wikimedia, photographs of a number of lesser-known encryption devices from Switzerland are available. Can a reader tell me more about them?

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.

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?

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?

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

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

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.