Some Resources on the History of Cryptography

Cryptography and history come together in today’s post. I am a student of history, and I find old cryptography, security and clandestine communication methods fascinating. In this post, I will talk about three technologies and a resource for learning more about the history of cryptography and other topics. We discuss some of this history in Learning Tree’s System and Network Security Introduction.


The Enigma was the primary encryption device for the German Army in World War II. Before its military use, it was also used in commerce and for other official government communication. Its history and operation are well-documented on Wikipedia and other sites.

Crypto enthusiasts have been fascinated by the Enigma for decades. There are only a few left, and most of those are in museums. One recently sold for US$365,000. There are, however, replicas for sale as kits or pre-built. Some are both look-alike and function-alike replicas, while some just function like the original. Of those, some are mechanical (as were the originals) and others emulate the machine electronically. One even uses paper.Enigma Machine


In WWII the U.S. also had a mechanical encryption device. It was known as SIGABA or the ECM Mark II. The inventors applied for a patent in 1945, and it was granted in 2001. For whatever reason, the SIGABA is not discussed as much as the Enigma, but it did play an important part in the history of encryption. Its most significant feature was that the rotors which did the encryption to advance “randomly” for each keypress as opposed to a single character at a time as in the Enigma. This made the encryption far harder to break.

Image from SIGABA patent

Lorenz Teleprinter

In May of 2016, a woman in England offered what she thought was an old “telegram machine” on eBay. It turned out to be part of a rare Lorenz cypher device of the type used by the Germans late in World War II. A volunteer with Britain’s National Museum of Computing saw the device and purchased it from the woman.

The design of Lorenz cipher was based on the Baudot code used by teleprinters of the day. Interestingly, it was developed in the US. The paper linked above discusses the operation of the machine and how the Allies broke it.

Lorenx encryption device is a treasure trove of documents. Some are current, and some are historical. One interesting current document is “How US Transnational Fiber Cables are Tapped.” That document may or may not be accurate, but it is surely interesting. Another document is “The Alternative History of Public-Key Cryptography” detailing the work of James Ellis on public-key crypto in the UK. Someone like me who is quite interested in history can spend hours reading this site. Some documents are heavily redacted as their content is still deemed classified.

I hope this has given you some sources for learning more about the history of cryptography. Please share other resources in the comments below.

To your safe computing,
John McDermott

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