Computer ◆ Conservation ◆ Society

Recreating the Polish Bomba, Predecessor to the Turing-Welchman Bombe

Speaker: Jerry McCarthy
Date: Thursday 16th May 2019
Time: 14:30

BCS, 5 Southampton St, London WC2E 7HA


About the seminar

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

About the speaker

Jerry’s day job used to be to write software, in areas such as retail systems, cryptography and internationalisation, for a global computing company. Since his retirement, he now volunteers at The National Museum of Computing (TNMOC), which is situated within the Bletchley Park Campus. There, he talks to visitors about, inter alia, Tunny, Colossus, and the Museum’s slide rule collection. 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.

Jerry is not rich enough to be a full-time cryptocollector, but is interested in crypto simulation techniques which allow virtual acquisition of crypto hardware without needing to find the space to store it. Jerry’s house is definitely not big enough for a Colossus!