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Alan Turing

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Vicky P

on 20 April 2015

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Transcript of Alan Turing

Alan Turing And Codebreaking

June 23rd 1912
Julius Mathison Turing and Ethel Sara Stoney

John Turing
Mathematics, cryptanalysis, computer science and Biology
Alan Turing joined the government codes and cypher school at Bletchley park
He worked on breaking the code for the German Enigma machine and invented a machine to break the code
His wartime services helped to win the war
Alan Turing
English mathematician, wartime code-breaker and pioneer of computer science
Had a colossal impact on the course of WW2.
Without his contributions, the war would have waged on for another 2 if not 3 years, costing up to 21 million lives

The Enigma code was almost impossible to decipher
The machine had the ability to encode messages without ever repeating a letter.
The German military machines had an extra layer of encoding: there was a "plugboard" at the front of the machine which allowed the coding to be resequenced for an extra layer of scrambling.
Based on the Polish Bomba, Alan Turing was able to develop a machine to decrypt the German messages called the Bombe
It was made by Alan Turing and Gordon Welchman whilst working in Bletchley Park
It enabled the World War II codebreakers to decipher high volumes of messages at speed and while still relevant

RAF could decipher messages about incoming attacks, but had to plan which German airplanes they should attack and which they should ignore
This sacrifice was necessary to avoid German suspicion that their codes were broken.
If the Germans knew their code was broken, they'd just change it.
Coventry Controversy
Coventry is an English city that was subject to many attacks during the course of WW2.
14th November, 1940: 515 German bombers dropped around 500 tons of bombs, killing 568 people, and seriously injuring 1293.
4,300 homes were destroyed and two-thirds of the city's buildings were damaged.

By Victoria, Lucy and Leandra
The Enigma Code
The Polish Bomba
The Poles were the first to break the military variant of the Enigma in 1932.
Their success was based on pure mathematical analysis, information from a German spy and a machine intercepted in the Polish mail.
The Germans initially used a simple key management scheme, but between September 1938 and May 1940, all settings were changed daily, making hand methods impracticable.
Alan Turing's Decoding Machine
Alan Turing
Bletchley Park
There have been rumours British government knew the attack was going to happen.
Winston Churchill ordered that no defensive measures should be taken to protect Coventry so the Germans wouldn't suspect that their cipher had been broken.
But this is believed to be no more than a myth.

Being able to decode German messages brought about the end of the war about 3 years faster, saving approximately 21 million lives.
There was a major flaw in the German keying procedures - the randomly chosen message key was sent enciphered twice at the beginning of the message.
This allowed Polish mathematicians to develop a semi-automatic machine called the Bomba.
The machine was used to recover the key-settings in (supposedly) under two hours.
Women were the predominant operators of Bletchley Park Bombes, decoding and translating intercepts for intelligence service use
The initial design of Bombe was designed in 1939
Each month had its own settings, printed on code sheets in soluble ink
If the Allied codebreakers deciphered the settings, their decryption would be useless weeks later
For the Enigma code to work, the sender and receiver had to have exactly the same settings on their rotors and plugboards
On March 31, 1952 Alan Turing was put on trial for having homosexual relations with a 19 year old
The police found out after they were investigating a burglary in his home
He was found guilty
His work was to be secret and not many people knew about his work at the time
Alan Turing
Alan Turing Goes on Trial for
Memorial to Alan Turing located Fairfield Street, Manchester M1 3HB, United Kingdom
Alan Turing wasn't well known at the time, but now he has a movie based on him and even a Monopoly game!
(left to right) Polish mathematicians Marian Rejewski, Jerzy Rózyki and Henryk Zygalski
Enigma Machine
He got a choice of spending one year in jail or go under hormone treatment
He chose hormone treatment
He died on June 7, 1954 from eating a poisoned apple - his death was believed to be a suicide

How the Bombe worked
The Bombe was a large collection of cogs operated by a motor, with relays and electronics to detect a match and sound an alert.
Each set of three cogs was a correlator that went through messages using a particular codeword and looking for a pattern match.
If they found the match, then they knew the setting used and could read the rest of the encoded text.
A diagram of the Bomba
A photo of the Bombe
Full transcript