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![]() Colossus computer - Wikipedia. Colossus computer. ![]() A Colossus Mark 2 computer being operated by Wrens. Dorothy Du Boisson (left) and Elsie Booker. The slanted control panel on the left was used to set the "pin" (or "cam") patterns of the Lorenz. The "bedstead" paper tape transport is on the right. Developer. Tommy Flowers assisted by Sidney Broadhurst, William Chandler and for the Mark 2 machines, Allen Coombs. Manufacturer. Post Office Research Station. Type. Special- purpose electronic digital programmable computer. Download Full Softwares with their Serial keys, Registration. Windows 7 Professional Permanent Activator You may find the Windows 7 professional activator in every. Design Master Electrical SoftwareGeneration. First- generation computer. Release date. Mk 1: December 1. Mk 2: 1 June 1. 94. Discontinued. 8 June 1. Units shipped. 10. Media. Electric typewriter output. Programmed, using switches and plug panels. CPUCustom circuits using thermionic valves and Thyratrons. A total of 1,6. 00 in Mk 1 and 2,4. Mk 2. Also relays and stepping switches. Memory. None (no RAM)Display. Indicator lamp panel. Input. Paper tape of up to 2. Power. 8. 5 k. W[1]Colossus was a set of computers developed by British codebreakers in 1. Lorenz cipher. Colossus used thermionic valves (vacuum tubes) to perform Boolean and counting operations. Colossus is thus regarded[2] as the world's first programmable, electronic, digital computer, although it was programmed by switches and plugs and not by a stored program. Colossus was designed by research telephone engineer Tommy Flowers to solve a problem posed by mathematician Max Newman at the Government Code and Cypher School (GC& CS) at Bletchley Park. Alan Turing's use of probability in cryptanalysis[4] contributed to its design. It has sometimes been erroneously stated that Turing designed Colossus to aid the cryptanalysis of the Enigma.[5] Turing's machine that helped decode Enigma was the electromechanical Bombe, not Colossus.[6]The prototype, Colossus Mark 1, was shown to be working in December 1. Bletchley Park by January 1. February 1. 94. 4.[9] An improved Colossus Mark 2 that used shift registers to quintuple the processing speed, first worked on 1 June 1. Normandy Landings on D- Day. Ten Colossi were in use by the end of the war and an eleventh was being commissioned. Bletchley Park's use of these machines allowed the Allies to obtain a vast amount of high- level military intelligence from intercepted radiotelegraphy messages between the German High Command (OKW) and their army commands throughout occupied Europe. The existence of the Colossus machines was kept secret until the mid- 1. This deprived most of those involved with Colossus of the credit for pioneering electronic digital computing during their lifetimes. A functioning rebuild of a Mark 2 Colossus was completed in 2. Tony Sale and some volunteers; it is on display at The National Museum of Computing at Bletchley Park.[1. Purpose and origins[edit]. Cams on wheels 9 and 1. An active cam reversed the value of a bit (0→1 and 1→0). The Colossus computers were used to help decipher intercepted radio teleprinter messages that had been encrypted using an unknown device. Intelligence information revealed that the Germans called the wireless teleprinter transmission systems "Sägefisch" (sawfish). This led the British to call encrypted German teleprinter traffic "Fish", and the unknown machine and its intercepted messages "Tunny" (tunafish).[1. Before the Germans increased the security of their operating procedures, British cryptanalysts diagnosed how the unseen machine functioned and built an imitation of it called "British Tunny". It was deduced that the machine had twelve wheels and used a Vernam ciphering technique on message characters in the standard 5- bit ITA2 telegraph code. It did this by combining the plaintext characters with a stream of key characters using the XORBoolean function to produce the ciphertext. In August 1. 94. 1, a blunder by German operators led to the transmission of two versions of the same message with identical machine settings. These were intercepted and worked on at Bletchley Park. First, John Tiltman, a very talented GC& CS cryptanalyst, derived a key stream of almost 4. Then Bill Tutte, a newly arrived member of the Research Section, used this key stream to work out the logical structure of the Lorenz machine. He deduced that the twelve wheels consisted of two groups of five, which he named the χ (chi) and ψ (psi) wheels, the remaining two he called μ (mu) or "motor" wheels. The chi wheels stepped regularly with each letter that was encrypted, while the psi wheels stepped irregularly, under the control of the motor wheels.[2. With a sufficiently random key stream, a Vernam cipher removes the natural language property of a plaintext message of having an uneven frequency distribution of the different characters, to produce a uniform distribution in the ciphertext. The Tunny machine did this well. However, the cryptanalysts worked out that by examining the frequency distribution of the character- to- character changes in the ciphertext, instead of the plain characters, there was a departure from uniformity which provided a way into the system. This was achieved by "differencing" in which each bit or character was XOR- ed with its successor.[2. After Germany surrendered, allied forces captured a Tunny machine and discovered that it was the electromechanical. Lorenz SZ (Schlüsselzusatzgerät, cipher attachment) in- line cipher machine. A Lorenz SZ4. 0 machine on display at the National Cryptologic Museum, Fort Meade, Maryland, USA. In order to decrypt the transmitted messages, two tasks had to be performed. The first was "wheel breaking", which was the discovery of the cam patterns for all the wheels. These patterns were set up on the Lorenz machine and then used for a fixed period of time for a succession of different messages. Each transmission, which often contained more than one message, was enciphered with a different start position of the wheels. Alan Turing invented a method of wheel- breaking that became known as Turingery.[2. Turing's technique was further developed into "Rectangling", for which Colossus could produce tables for manual analysis. Colossi 2, 4, 6, 7 and 9 had a "gadget" to aid this process.[2. The second task was "wheel setting", which worked out the start positions of the wheels for a particular message, and could only be attempted once the cam patterns were known.[2. It was this task for which Colossus was initially designed. To discover the start position of the chi wheels for a message, Colossus compared two character streams, counting statistics from the evaluation of programmable Boolean functions. The two streams were the ciphertext, which was read at high speed from a paper tape, and the key stream, which was generated internally, in a simulation of the unknown German machine. After a succession of different Colossus runs to discover the likely chi- wheel settings, they were checked by examining the frequency distribution of the characters in processed ciphertext. Colossus produced these frequency counts. Decryption processes[edit]By using differencing and knowing that the psi wheels did not advance with each character, Tutte worked out that trying just two differenced bits (impulses) of the chi- stream against the differenced ciphertext would produce a statistic that was non- random. This became known as Tutte's "1+2 break in".[3. It involved calculating the following Boolean function: ∆Z1 ⊕ ∆Z2 ⊕ ∆χ{\displaystyle \chi }1 ⊕ ∆χ{\displaystyle \chi }2 = •and counting the number of times it yielded "false" (zero). If this number exceeded a pre- defined threshold value known as the "set total", it was printed out. The cryptanalyst would examine the printout to determine which of the putative start positions was most likely to be the correct one for the chi- 1 and chi- 2 wheels. This technique would then be applied to other pairs of, or single, impulses to determine the likely start position of all five chi wheels. From this, the de- chi (D) of a ciphertext could be obtained, from which the psi component could be removed by manual methods.
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