Other articles in the series:
- History of the relay
- History of electronic computers
- History of the transistor
- Internet history
In 1938, the head of British Secret Intelligence quietly purchased a 24-hectare estate 80 miles from London. It was located at the crossroads of railways from London north and from Oxford in the west to Cambridge in the east, and was the perfect location for an organization that no one was supposed to see, yet located within easy reach of most of the important centers of knowledge. and British authorities. The property known as , became the British center for breaking ciphers during World War II. This is perhaps the only place in the world known for its involvement in cryptography.
Tunney
In the summer of 1941, work was already in full swing in Bletchley to crack the famous Enigma cipher machine used by the German army and navy. If you watched the film about the British codebreakers, then they talked about Enigma, but we will not expand on it here - because shortly after the invasion of the Soviet Union, Bletchley discovered the transmission of messages with a new type of encryption.
Cryptanalysts soon figured out the general nature of the machine they used to transmit messages, which they nicknamed "Tunny".
Unlike Enigma, whose messages had to be deciphered by hand, Tunny connected directly to the teletype. The teletype machine converted each character entered by the operator into a stream of dots and crosses (similar to Morse code dots and dashes) in standard with five characters per letter. It was unencrypted text. Tunny used twelve wheels at once to create her own parallel stream of dots and crosses: the key. She then added a key to the message, producing a ciphertext transmitted over the air. The addition was done in binary arithmetic, where dots corresponded to zeros, and crosses corresponded to ones:
0 + 0 = 0
0 + 1 = 1
1 + 1 = 0
Another Tunny on the receiver's side with the same settings would give the same key and add it to the encrypted message to give the original, which was printed on paper by the receiver's teletype. Let's say we have a message: "dot plus dot dot plus". In numbers it will be 01001. Let's add a random key: 11010. 1 + 0 = 1, 1 + 1 = 0, 0 + 0 = 0, 0 + 1 = 1, 1 + 0 = 1, so we get the ciphertext 10011. By adding the key again, the original message can be restored. Let's check: 1 + 1 = 0, 1 + 0 = 1, 0 + 0 = 0, 1 + 1 = 0, 0 + 1 = 1, we get 01001.
Parsing Tunny's work was facilitated by the fact that in the early months of using it, senders passed on wheel settings to be used before sending a message. Later, the Germans released codebooks with pre-set wheel settings, and the sender only needed to send a code by which the recipient could find the desired wheel setting in the book. They ended up changing the codebooks daily, causing Bletchley to have to hack the codewheel settings every morning.
Interestingly, cryptanalysts have figured out the Tunny function based on the location of the sending and receiving stations. It connected the nerve centers of the German high command with the army and army group commanders on various European military fronts, from occupied France to the Russian steppes. It was a tempting task: Tunny's hack promised direct access to the enemy's top-level intentions and capabilities.
Then, through a combination of the mistakes of German operators, cunning and stubborn determination, the young mathematician went much further than mere conclusions about Tunney's work. Without seeing the machine itself, he fully determined its internal structure. He logically deduced the possible positions of each wheel (each of which had its own prime number), and how exactly the arrangement of the wheels generated the key. Armed with this information, Bletchley built replicas of the Tunny that could be used to decipher messages once the wheels were properly tuned.
12 wheels of the key to the Lorenz cipher machine known as Tunny
Heath Robinson
By the end of 1942, Tat continued to attack Tanni, developing a special strategy for this. It was based on the concept of delta: modulo 2 sum of one signal in a message (dot or cross, 0 or 1) with the next one. He realized that due to the intermittent movement of Tunny's wheels, there was a relationship between the delta of the ciphertext and the delta of the keytext: they had to change together. So if you compare the ciphertext with the keytext created on different wheel settings, you can calculate the delta for each and count the number of matches. Much more than 50% hits should mark a potential candidate for a real message key. The idea was good in theory, but it was impossible to put it into practice, since it required 2400 passes for each message to check all possible settings.
Tut took the problem to another mathematician, Max Newman, who ran a department at Bletchley that everyone called "newmania". Newman, on the face of it, was an unlikely choice to lead the sensitive British intelligence organization, since his father was from Germany. However, it seemed unlikely that he would be spying for Hitler, since his family was Jewish. He was so concerned about the progress of Hitler's dominance in Europe that he moved his family to the safety of New York shortly after the collapse of France in 1940, and for a time he himself considered moving to Princeton.
Max Newman
It so happened that Newman had the idea of ββworking on the calculations required by Tata's method - through the creation of a machine. Bletchley was already accustomed to using machines for cryptanalysis. This is how Enigma was cracked. But Newman conceived a specific electronic device to work on the Tunney cipher. Before the war, he taught at Cambridge (one of his students was Alan Turing), and knew about the electronic counters built by Wynn-Williams to count particles at the Cavendish. The idea was this: if you synchronized two tapes closed in a loop, scrolling at high speed, one of which will have a key and the other an encrypted message, and consider each element a processor that counts deltas, then an electronic counter could sum up the results. By reading the final score at the end of each run, it was possible to decide whether this key was a potential one or not.
It so happened that a group of engineers with the right experience just existed. Among them was Winn-Williams himself. Turing recruited Wynn-Williams from the Radar Lab in Malvern to help build a new rotor for an Enigma decoding machine that uses electronics to count turns. He was assisted on this and another Enigma project by three engineers from the Dollis Hill Postal Research Station: William Chandler, Sidney Broadhurst and Tommy Flowers and for telegraphy and telephony). Both projects failed and the men were left without work. Newman collected them. He put Flowers in charge of a team that was building a "combiner" that would count deltas and feed the result to a counter Wynn-Williams was working on.
Newman kept the engineers building the machines, and the Women's Department of the Royal Navy running his messaging machines. The government entrusted high leadership positions only to men, and women did a good job working as tellers in Bletchley - they were engaged in both transcription of messages and decoding settings. They very organically managed to move from clerical work to taking care of the machines that automate their work. They frivolously called their ward car "', the British equivalent [both were illustrators-cartoonists depicting extremely complex, cumbersome and intricate devices that performed very simple functions / approx. transl.].
The "Old Robinson" car, very similar to its predecessor, the "Heath Robinson" car
And indeed, "Heath Robinson", in theory quite reliable, in practice suffered from serious problems. The main thing was the need for perfect synchronization of the two tapes - the cipher text and the key text. Any stretching or slipping of any of the films rendered the entire passage unusable. To minimize the risk of errors, the machine processed no more than 2000 characters per second, although belts could work faster. Flowers, who reluctantly agreed with the work of the Heath Robinson project, believed that there was a better way: a machine built almost entirely from electronic components.
Colossus
Thomas Flowers worked as an engineer in the research department of the British Post Office from 1930, where he initially worked on the investigation of incorrect and failed connections in new automatic telephone exchanges. This led him to think about how to create an improved version of the telephone system, and by 1935 he began to advocate the replacement of the electromechanical components of the system, such as relays, with electronic ones. This goal determined his entire future career.
Tommy Flowers, around 1940
Most engineers have criticized electronic components for being fussy and unreliable when used on a large scale, but Flowers showed that when used continuously and at much lower powers than expected, vacuum tubes actually exhibit astonishingly long lifespans. He proved his ideas by replacing all the terminals that set the communication tone on a switch that served 1000 lines with lamps; in total there were 3-4 thousand of them. This installation was launched into real work in 1939. During the same period, he experimented with replacing the relay registers that store telephone numbers with electronic relays.
Flowers believed that the Heath Robinson he was hired to build was seriously flawed, and that he could do a much better job with more lamps and fewer mechanical parts. In February 1943, he brought an alternative design of the machine to Newman. Flowers cleverly got rid of the film with the key, eliminating the synchronization problem. His machine was supposed to generate key text on the fly. She had to simulate Tunny electronically, going through all the wheel settings and comparing each one to the ciphertext, writing down the likely matches. He calculated that such an approach would require the use of about 1500 vacuum tubes.
Newman and the rest of Bletchley's leadership were skeptical of the proposal. Like most of Flowers' contemporaries, they doubted whether electronics could be made to work on such a scale. Besides, even if it could be made to work, they doubted such a machine could be built in time to be useful in war.
Flowers' boss at Dollis Hill did give him the go-ahead to assemble a team to build this electronic monster - Flowers may not have been completely sincere in describing how Bletchley liked his idea (According to Andrew Hodges, Flowers told his boss, Gordon Radley, that the project was Bletchley's critical work, and Radley had already heard from Churchill that Bletchley's work was an absolute priority). In addition to Flowers, Sidney Broadhurst and William Chandler played a large role in the development of the system, and the whole idea employed almost 50 people, half the resources of Dollis Hill. The team was inspired by precedents used in telephony: counters, branching logic, equipment for routing and signaling, and equipment for periodic measurements of the state of equipment. Broathurst was a master of such electromechanical circuits, while Flowers and Chandler were electronics experts who understood how to transfer concepts from the world of relays to the world of valves. By early 1944 the team had a working model at Bletchley. The giant machine was named "Colossus", and quickly proved that it could outshine "Heath Robinson" by reliably processing 5000 characters per second.
Newman and the rest of the leadership at Bletchley quickly realized that they had made a mistake in turning Flowers down. In February 1944, they ordered 12 more Colossi, which were supposed to be in service by June 1 - the invasion of France was planned for this date, although, of course, Flowers did not know this. Flowers said bluntly that this was impossible, but with heroic effort, his team managed to deliver a second car by May 31, in which a new member of the team, Alan Coombs, made many improvements.
The revised layout, known as the Mark II, continued the success of the first machine. In addition to the film feed system, it consisted of 2400 lamps, 12 rotary switches, 800 relays, and an electric typewriter.
Colossus Mark II
It was customizable and flexible enough to handle a variety of tasks. After installation, each of the women's teams tuned their Colossus to solve certain problems. A switchboard, similar to a telephone operator's panel, was needed to set up electronic rings that simulated Tunny's wheels. A set of switches allowed operators to set up any number of functional apparatuses that processed two streams of data: an external film and an internal signal generated by the rings. By combining a set of different logical elements, "Colossus" could calculate arbitrary Boolean functions based on the data, that is, such functions that would give out 0 or 1. Each unit increased the "Colossus" counter. A separate control apparatus made branching decisions based on the state of the counter - for example, to stop and print the output if the counter value exceeded 1000.
Switch panel for setting "Colossus"
Let us assume that the Colossus would be a general-purpose programmable computer in the modern sense. He could logically combine two streams of data - one on tape and one generated by ring counters - and count the number of ones encountered, and that's it. Much of the "programming" of the Colossus was done on paper, with operators executing a decision tree prepared by analysts: say, "if the system output is less than X, set configuration B and execute Y, otherwise execute Z."
High-level block diagram for "Colossus"
Nevertheless, "Colossus" was quite able to solve the task assigned to him. Unlike the Atanasoff-Berry computer, Colossus was extremely fastβit could process 25000 characters per second, each of which could require multiple Boolean operations. The Mark II is five times faster than the Mark I, while simultaneously reading and processing five different sections of film. It refused to connect the entire system with slow electromechanical I / O devices, using photocells (taken from anti-aircraft ) to read incoming tapes, and a registry to buffer typewriter output. The leader of the team that restored the Colossus in the 1990s showed that he could still easily outperform a 1995 Pentium-based computer in his business.
This powerful word processing machine became the center of a project to break the Tunny code. Before the end of the war, ten more Mark IIs were built, the panels for which were stamped one piece a month by workers at a postal factory in Birmingham, who had no idea what they were making, and then they were assembled in Bletchley. One exasperated official from the Ministry of Supply, having received another request for a thousand special valves, asked if the postal workers were shooting them at the Germans. In this industrial way, and not by hand-assembly of an individual project, the next computer will be produced no earlier than the 1950s. Flowers instructed each Colossus to work day and night until the very end of the war to protect the valves. They stood quietly glowing in the dark, warming up the wet British winter, waiting patiently for instructions until the day came when they were no longer needed.
Veil of Silence
Natural enthusiasm for the intriguing drama that was unfolding at Bletchley led to an over-exaggeration of the military achievements of this organization. It's awfully absurd to insinuate how the film does it"[The Imitation Game] that British civilization would cease to exist if not for Alan Turing. "Colossus", apparently, had no effect on the course of the war in Europe. His most publicized accomplishment was proving that the 1944 Normandy landing deception had worked. Messages received through Tunney indicated that the Allies had successfully convinced Hitler and his command that the real strike would come further east, at the Pas de Calais. Encouraging information, but it is unlikely that the decrease in the level of cortisol in the blood of the allied command helped win the war.
On the other hand, the technological advances that Colossus introduced were undeniable. But the world won't know for a while. Churchill ordered that all Colossi that existed at the end of the game be dismantled and the secret of their device sent along with them to the landfill. Two cars somehow survived this death sentence, and remained in the ranks of British intelligence until the 1960s. But even then the British government did not lift the veil of silence about the work in Bletchley. It was not until the 1970s that its existence became public knowledge.
The decision to permanently ban all discussion of the work being carried out at Bletchley Park could be described as over-cautiousness on the part of the British government. But for Flowers, it was a personal tragedy. Deprived of all the merit and prestige of the inventor of the Colossus, he suffered dissatisfaction and frustration when his constant attempts to replace relays with electronics in the British telephone system were constantly blocked. If he could demonstrate his achievement with the example of "Colossus", he would have the influence necessary to realize his dream. But by the time his achievements became known, Flowers had long retired and could not influence anything.
A few electronic computing enthusiasts scattered around the world suffered from similar problems with the secrecy surrounding the Colossus and the lack of evidence for the viability of this approach. Electromechanical calculations could remain the main thing for some time. But there was another project that would pave the way for the rise to the dominance of electronic computing. Although it was also the result of secret military developments, it was not hidden after the war, but, on the contrary, was revealed to the world with the greatest aplomb, under the name ENIAC.
What to read:
β’ Jack Copeland, ed. Colossus: The Secrets of Bletchley Park's Codebreaking Computers (2006)
β’ Thomas H. Flowers, βThe Design of Colossus,β Annals of the History of Computing, July 1983
β’ Andrew Hodges, Alan Turing: The Enigma (1983)
Source: habr.com