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.


Peter Nüchterlein, the writer-in-residence in Wernigerode, Germany, has asked me for help. In a Vienna archive he has found over 100 encrypted documents from the Thirty Years’ War. Today, I am going to introduce five of them. Can a reader decipher them?


Can you decipher this encrypted graffiti that was found near Rome, Italy? The encryption method used looks like a Pigpen variant.


Designing a secure manual encryption algorithm is a challenge. Some cryptographers have developed ciphers that require a deck of playing cards. The best-known one of this kind is Bruce Schneier’s Solitaire. Today, I am going to introduce another one: Talon by Aaron Toponce.


20 years ago, Jim Gillogly, a great codebreaker and reader of this blog, created three crypto challenges – a Playfair, a Double Playfair, and a Double Column Transposition. Can you solve them?


Three months ago, I presented a terminology for codes and nomenclators, based on a workshop that took place at the HistoCrypt conference. After having received some interesting feedback, I can now provide an update.


A message written 118 years ago in Aldino, Maryland, waits to be solved. Can you break this cryptogram?


The Vernam cipher is mentioned in dozens of cryptography books. It is simple and more secure than most other basic encryption methods. Can you solve the three Vernam challenges I am going to introduce today?


An advertisment poster an Instagram user has seen in a New York subway is completely encrypted. Can you decipher it? And can you tell me what is behind the “spiritual consultancy” that has published this poster and a few others?


In the Cold War, US scientist Gus Simmons discovered a serious weakness in a cryptologic disarmament technology. His discovery initiated a new branch of IT security. Nevertheless, nobody seems to know how this weakness worked. The paper Simmons published about it doesn’t contain a detailed description. Does a reader know more?


Can a reader decipher this encrypted diary page I found on the internet? I don’t know by whom and when it was written, but I’m sure that it can be solved.