Rotor Ciphers History Invented in 1915 by Theo
Rotor Ciphers
History § Invented in 1915 by Theo A. van Hengel and R. P. C. Spengler § Edward Hugh Hebem developed a rotor machine in the United States in 1917. § Arthur Sherbius designed the Engima machine. § Marian Rejewski broke the Enigma machine in 1932.
Mechanization § § § Rotors have 26 positions. Multiple rotors per machine User enters a character § Electrical current goes through rotor § Rotor rotates § Next time same character is pressed, different cipher character is produced
Mechanization § Key is pressed § Current goes through rotor § Cipher character lightbulb lights up § Rotor rotates § Reflector (only in Enigma) made decryption the same as encryption, but was flawed
Mechanization (Decryption) § To decrypt, the user must know: § Wheel order – The choice of rotors and their order § Initial position of the rotors – Chosen by operator, changed for each message § Ring settings – Position of the alphabet ring relative to the rotor wiring (shift cipher) § Plug settings - Connections of plugs in plugboard (plugboard connects pairs of letters and switches them before and after main rotor)
Mechanization (Decryption) § To decrypt, the rotors were taken out and turned around from the encryption position to reverse the circuitry. § This was not necessary in the Enigma because of the reflector.
Cryptanalysis § The unsteckered Enigma (without plugboard) was easily broken. § The Polish discovered that they keyboard was arranged ABCDEF, as opposed to QWERTY. § A French spy provided information to the Polish that allowed them to create a replica Enigma machine. § The Polish broke the Enigma machine in 1932 through algebra.
Cryptanalysis § The reflector was a flaw in Enigma machines. § The Polish invented a device known as a cryptologic bomb, which was essentially six Enigma machines. § The Germans constantly made more complex Enigma machines (such as the Kriegsmarine Enigma).
Bibliography § http: //www. burningwell. org/gallery 2/d/29742/ttenigma 4. jpg § http: //cleavebooks. co. uk/trolc 07. pdf § http: //en. wikipedia. org/wiki/Cryptanalysis_of_th e_Enigma § http: //en. wikipedia. org/wiki/Rotor_machine § http: //en. wikipedia. org/wiki/Enigma_machine
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