The sounds of the second world war go beyond the haze of gunfire and bombs. One of the lesser-known, yet prolific, noises was the steady hum of the Lorenz SZ cipher attachment – the machine that fundamentally changed the role of communication in warfare. Now, to mark the passing of 100 years since the birth of Bletchley code-cracker Bill Tutte, a virtual Lorenz machine has been created to experience online.
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The Lorenz SZ40, SZ42A and SZ24B were teleprinter cipher attachment machines developed by C. Lorenz AG in Berlin during the second world war. The SZ model name is from the German "Schlüssel-Zusatz" which means cipher attachment. The Enigma cipher machine was portable enough for frontline troops, but it required two operators at each end of the link – one to encipher the message, a letter at a time, and another to transmit it via Morse code. Through analysing these codes, Tutte was able to determine how the Lorenz machine worked and gained a game-changing insight into German messages.
Without ever having seen it, Tutte found that the Lorenz used 12 separate wheels and a series of switches to turn text into nonsensical ramblings. From this, it could produce more than 16 billion potential combinations. With so many combinations possible, it's no surprise the team at Bletchley demanded researchers from a variety of different backgrounds.
The Bletchley team was one of the most diverse of its time, with more than 50 per cent women. The code-breaking at Bletchley laid the foundations for one of the first computers, the Colossus, as well as the drive to push boundaries in tech that we still see today. Alan Turing famously countered the Lorenz code with the 'Turingery’ technique. It was one of the first instances of electronic equipment being used to drastically change the course of politics and warfare. It also formed the basis for today's theories of encryption.
There are only four Lorenz SZ42's in the world and none are in working order. This digital Lorenz machine is an invaluable way of educating the public about the history of ciphers and coding machines, as well as giving them the tools to encode their own messages.
With the virtual Lorenz, you can watch your words transformed into coded messages in real time. Adapt the wheels of the cipher to change the code, or use the Auto-text function to run a message naturally through the machine. Complete with the Lorenz's original instructions – Ein for on and Aus for off. Take off the hood to watch the Lorenz wheels shift when you change the letter combinations.
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The original Lorenz worked by sending electrical impulses to signify letters of the alphabet – each letter can be represented by a five-bit code, or the absence of code. This signal was then encoded onto paper tape in a series of holes and relayed. The Vernan method, which was later used in the Lorenz machine, incorporated a string of random characters to each code, therefore making it harder to break. The problem with this method in wartime was ensuring that both parties communicating would have the same set of random codes. Without knowing which code was random, and which wasn't, it would be extremely difficult for those even on the same side of the war to decipher messages.
The Lorenz adapted the Vernan method of coding by creating a machine that could generate this random code and relay it. So long as the message receiver had a similar machine, the Lorenz could set a certain start point and generate letters in the place of codes. To make sure the randomly generated string of characters did not repeat too often, it was decided to have two sets of wheels so it is essentially adding two separate letters to the initial letter to get the final cipher character to send.
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To enable even more differences to the mix, two separate motor wheels were added which changed how often the second character wheels turned. This created the iconic machine we recognise today. With the different wheel combinations, the number of possible ways of setting the wheels without touching the pins is 43 × 47 × 51 × 53 × 59 × 37 × 61 × 41 × 31 × 29 × 26 × 23 = 1.6034 × 1019 while taking into account the pin settings too makes a total of 1.0 x 10170. This is more combinations than there are particles in the Universe.
Security in communication is an issue played out across the media and is at the forefront of people's minds. With debates surrounding encryption and hacking, one surprising element of the Virtual Lorenz is that it lets anyone encrypt their own text with the virtual enciphering machine. Those using the site can also connect to other people using the SZ42 and talk to them via an encrypted channel. With this digital update to analogue ciphers, a piece of the second world war has been brought into the 21st century.
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This article was originally published by WIRED UK
