COLOSSUS COMPUTER HOW TO
COLOSSUS COMPUTER MANUAL
COLOSSUS COMPUTER CODE

This was generally done using a few methods including from messages in depth (where several messages were received enciphered with the same key) in a process devised by Alan Turing called Turingery. Wheel breaking meant working out the pin settings of all 501 pins on each of the twelve Lorenz cipher wheels. We will assume that we have already broken the wheel patterns for this message. Once the start positions of each of the twelve rotors are calculated, we can use a Lorenz machine to try to decipher the final message.įollow this for more information on Cryptanalysis of the Lorenz cipher.

COLOSSUS COMPUTER CODE

There wasn't a set program which would run to work out the settings, it was a matter of following a 'menu' of different algorithms and sometimes required knowledge of what worked on a particular radio link.Ĭolossus was not able to run a sequence of algorithms or use the results of previous calculations (like we would expect from a computer today), each run required a decision by the operator or code breaker assigned to that machine on which operation would be the next best to run. This document will take you through an example process used on Colossus to get the start positions of a received message. The final two went to Eastcote, North London and then on to GCHQ in Cheltenham where they ran until the 1960s. The existence of this first step in computing only came to light after 1970 when some details and photos started to be released. Many more Colossus computers were ordered and ten were running by the end of the war, assisting in the deciphering of a huge number of messages.Īfter the war was over, the majority of the Colossus machines were dismantled and destroyed and all notes and drawings burned to keep the secrecy of the code breaking at Bletchley Park. He knew from his research using valves for fast telephone switching systems, that they were perfectly reliable as long as you kept them switched on.īy the end of 1943, the first Mark 1 Colossus was completed and was reassembled at Bletchley Park in January 1944 where it's initial demonstration completed without a flaw. Undeterred, he returned to Dollis Hill and persuaded the GPO to set about creating the machine anyway. He suggested a new machine which would use over 1,000 valves (vacuum tubes) but this was rejected as it was believed that so many valves would be unreliable. A brilliant electronics engineer, Tommy Flowers, was brought in from the GPO research station to see if he could help make this machine work correctly. It worked well enough to prove the concept, but had issues running consistently.

COLOSSUS COMPUTER MANUAL

Over the next couple of months, Tutte and the other members of the Research section carried on to get a complete logical structure of the cipher machine which we now know to be the Lorenz, without ever seeing the physical machine! Bill Tutte also went on to work out a statistical way in which the cipher could be broken, but it required a huge amount of manual calculation which could take weeks of work.Ī mathematician, Max Newman, thought that it would be possible to automate the process using a machine, and had built a counting machine which became known as Heath Robinson. He also worked out that one set of wheels always stepped on each letter entered while the other set only moved some of the time. He called these the Psi (Ψ) and Chi (Χ) wheels. He also deduced that there were two rather than one wheel generating each impulse of the key string. This turned out to be the number of starting positions of one of the rotors in the machine. After a while, he tried writing just the first channel of the key in rows of 41 and started to see patterns emerge which meant that the repetition period of 41 had some significance in the way the cipher was generated. Unable to make any further headway, the messages and key were given to a new code breaker who had recently joined at Bletchley Park, Bill Tutte. This was deciphered and the key obtained by Brigadier John Tiltman, one of the top code breakers at Bletchley Park. The original break into this machine came when a mistake made by a German operator on 30th August 1941 meant two slightly differing messages were received, both enciphered with the same key generated by the Lorenz. They assisted with the breaking of the German Lorenz cipher attachment, a machine created to encipher communications between Hitler and his generals on the front lines. Ten computers were designed by Tommy Flowers and built at the Post Office Research Labs at Dollis Hill in 1943 during World War 2.

COLOSSUS COMPUTER HOW TO

Article written by How to use Colossus About ColossusĬolossus is the name of the world's first electronic computer.