A Virtual Talk by Jerry McCarthy.

In the mid-to-late 1930s, Polish mathematicians created a number of methodologies to decrypt messages sent using the 3-rotor Enigma.
In this talk, Jerry will:

• Explain the considerable variety of known Enigma machines. Enigma is not just a machine; it’s an entire family!
• Provide an introduction to cryptography starting at the Caesar Cipher and ending on focussing on the operation of one particular common Enigma machine variant.
• Discuss some of the Polish methodologies for cracking that machine, and finally focus on the Bomba created by three Polish mathematicians in the late 1930s, which was a device which took advantage of the message protocols used at that time, and for which the speaker has developed a working model using a mixture of ancient and modern techniques. A basic prototype will be described, and the subsequent working model will be demonstrated and explained in some detail. Some extensions to its original functionality will also be discussed.
• Explain the differences between the Bomba and the Turing-Welchman Bombe.

This will be followed by a Q&A session.

Jerry is a volunteer at TNMOC where he talks to visitors about Tunny, Colussus and the museums slide rule collection. Before his retirement, he wrote software in areas such as retail systems, cryptography and internationalisation for a global computing company. He also volunteers at the Instytut Józefa Piłsudskiego, where he gives the occasional talk on matters cryptological, such as Enigma and early Polish systems for breaking it.

Recorded 28th February 2021.