Hal Evans, a Cambridge graduate Master of Engineering, was able to build a fully functional replica of an electromechanical cryptology device known as the Rejewski Cyclometer. It was the predecessor to the Bombe, which Alan Turing used during World War II to crack the Enigma encryption machine of the Nazis. Other Rejewski cyclometers have not existed for 80 years, all existing samples were destroyed in 1939, when Germany occupied Poland. Polish mathematicians who worked with Rejewski on the project managed to transfer only the technology to the UK, but not the devices themselves.
By modern standards, a cyclometer is a very complex and irrationally expensive machine to manufacture, since it has no digital technologies, only analog mechanisms. And therefore, most researchers limited themselves to software emulators, but Evans, while still in his fourth year of study, was carried away by the works of Marian Rejewski and fired up the idea of building his cyclometer. In Cambridge, he was supported and even allocated funding, because Raevsky's technologies formed the basis for the developments of Alan Turing, a graduate of the same university.
Turing went down in history as the creator of the "Bombe" - a machine for breaking the German encryption device "Enigma". In reality, the Enigma encryption algorithms appeared long before the Bombe, and Polish mathematicians had several years to study them and develop decryption methods. In fact, they were the first to do this, but the Germans learned about their successes and complicated the code, after which a fierce race began during the war - some tried to break the code all the time, others modernized it.
Rejewski was among the first to understand the Enigma vulnerability, the code of which depended on the starting position of the rotors. True, there were more than 100, 000 of them. The developers of "Enigma" proceeded from the fact that a person simply cannot process such a volume of data, so Reevsky made a breakthrough by creating a prototype of a device for quick automatic decryption. Its design was constantly changing as the code itself and the Enigma were modernized, and as a result, the cyclometers never went beyond the cryptanalysis laboratories. All the more difficult it was for Hal Evans to build such a machine in the 21st century - but he succeeded.