Lec03_Breaking_the_Enigma

Lec03_Breaking_the_Enigma - Rotor Machines and Breaking The...

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1 1 Rotor Machines and Breaking The Enigma Prof. Ren Prof. Ren 2 Rotor Machines Before modern ciphers, rotor machines were most common product cipher Widely used in WWII German Enigma, Japanese Purple, Allied Hagelin, Implemented a very complex, varying substitution cipher Used a series of cylinders, each giving one substitution, which rotated and changed after each letter was encrypted
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2 Prof. Ren 3 Enigma Invented commercially in 1923. Adopted by Nazi’s. About 50,000 in use. Modified throughout WWII, believed to be perfectly secure. Based on three rotors performing varying substituted ciphertext letters for plaintext letters. Next, this new letter would be bounced off of a reflector, and back through the three rotors in reverse order. Prof. Ren 4 Enigma As the plain text letter passed through the first rotor, the first rotor would rotate one position. The other two rotors would remain stationary until the first rotor had rotated 26 times, the second rotor would rotate one position. After the second rotor had rotated 26 times, the third rotor would rotate one position. The rotors have 26 x 26 x 26 = 17,576 possible positions.
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3 Prof. Ren 5 Enigma The real Enigma in the the National Security Agency Museum Prof. Ren 6 Enigma-Rotors Close-up of rotors inside of machine. Reflector is to the left
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4 Prof. Ren 7 Enigma-Reflector Prof. Ren 8 Enigma-Rotors
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5 Prof. Ren 9 Enigma-Rotors Prof. Ren 10 Enigma-Rotors
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6 Prof. Ren 11 Enigma Prof. Ren 12 Enigma
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7 Prof. Ren 13 Prof. Ren 14 Enigma http://russells.freeshell.org/enigma/
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8 Prof. Ren 15 Security of Enigma - plugboard
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Lec03_Breaking_the_Enigma - Rotor Machines and Breaking The...

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