Rotor Machines
Rotor machine
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A series of three rotors from an Enigma machine, used by Germany during World War II
In cryptography, a rotor machine is an electro-mechanical device used for encrypting and decrypting secret messages. Rotor machines were the cryptographic state-of-the-art for a brief but prominent period of history; they were in widespread use in the 1930s–1950s. The most famous example is the Enigma machine.
The primary component is a set of rotors, also termed wheels or drums, which are rotating disks with an array of electrical contacts on either side. The wiring between the contacts implements a fixed substitution of letters, scrambling them in some complex fashion. On its own, this would offer little security; however, after encrypting each letter, the rotors advance positions, changing the substitution. By this means, a rotor machine produces a complex polyalphabetic substitution cipher.
Contents
[hide]
• 1 Background
• 2 Mechanization
• 3 History o 3.1 Invention o 3.2 The Enigma machine o 3.3 Various machines
• 4 List of rotor machines
• 5 References
• 6 External links
[edit] Background
40-point rotors from a machine made by Tatjana van Vark
In classical cryptography, one of the earliest encryption methods was the simple substitution cipher, where letters in a message were systematically replaced using some secret scheme. Monoalphabetic substitution ciphers used only a single replacement scheme — sometimes termed an "alphabet"; this could be easily broken, for example, by using frequency analysis. Somewhat more secure were schemes involving multiple alphabets, polyalphabetic ciphers. Because such schemes were implemented by hand, only a handful of different alphabets could be used; anything more complex would be impractical. However, using only a few alphabets left the ciphers vulnerable to attack. The invention of rotor
From Wikipedia, the free encyclopedia
(Redirected from Rotor machines)
Jump to: navigation, search
A series of three rotors from an Enigma machine, used by Germany during World War II
In cryptography, a rotor machine is an electro-mechanical device used for encrypting and decrypting secret messages. Rotor machines were the cryptographic state-of-the-art for a brief but prominent period of history; they were in widespread use in the 1930s–1950s. The most famous example is the Enigma machine.
The primary component is a set of rotors, also termed wheels or drums, which are rotating disks with an array of electrical contacts on either side. The wiring between the contacts implements a fixed substitution of letters, scrambling them in some complex fashion. On its own, this would offer little security; however, after encrypting each letter, the rotors advance positions, changing the substitution. By this means, a rotor machine produces a complex polyalphabetic substitution cipher.
Contents
[hide]
• 1 Background
• 2 Mechanization
• 3 History o 3.1 Invention o 3.2 The Enigma machine o 3.3 Various machines
• 4 List of rotor machines
• 5 References
• 6 External links
[edit] Background
40-point rotors from a machine made by Tatjana van Vark
In classical cryptography, one of the earliest encryption methods was the simple substitution cipher, where letters in a message were systematically replaced using some secret scheme. Monoalphabetic substitution ciphers used only a single replacement scheme — sometimes termed an "alphabet"; this could be easily broken, for example, by using frequency analysis. Somewhat more secure were schemes involving multiple alphabets, polyalphabetic ciphers. Because such schemes were implemented by hand, only a handful of different alphabets could be used; anything more complex would be impractical. However, using only a few alphabets left the ciphers vulnerable to attack. The invention of rotor