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.

Blog reader Mario Gerlach has provided me a picture of an encrypted graffiti he saw in Nördlingen, Germany. Can a reader solve this cryptogram?

Earlier this week I gave an interview (in German) about Crypto AG and the RUBICON affair. It is now available online.

According to recent press reports, the CIA and the BND secretly acquired Swiss crypto machine manufacturer Crypto AG and sold backdoored encryption technology.

An encrypted diary recently posted on Reddit looks easy to solve, but so far nobody has broken it.

On Reddit I found two messages allegedly left behind by people who committed suicide.

For the first time in over ten years, the FBI has published a challenge cipher. Can you solve it?

Today I’m going to introduce an alternate reality game (ARG) created by US puzzle designer Zachary Epstein. It was launched only a few days ago.

Jim Sanborn, creator of the famous Kryptos sculpture, has published a third clue: the word NORTHEAST appears in the plaintext of the unsolved message part.

Here are two cryptograms that are easy to solve: a postcard sent from Dortmund, Germany, in September 1900 and another one sent from the same place a few weeks later.

Today I’m presenting a 24 letter message that has been encrypted with a Playfair cipher. Such a short Playfair cryptogram has never been solved before.