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Computer Security and Cryptography by Alan G. Konheim

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7.3 COMPONENTS OF THE RED MACHINE

The components of the RED machine include

  1. A 60-contact half-rotor wired so that it enciphers vowels to vowels and consonants to consonants.

TABLE 7.2 Half-Rotor Substitution Table for θ

image

2. A plugboard connecting typewriter (input) to the rotor slip rings, where the typewriter keys for

(a) vowels A, E, I, O, U, and Y are connected to the six vowel slip rings, and

(b) consonants B, C, D, F,…, X, Z are connected to the 20 consonant slip rings.

3. A 47-position breakwheel, depicted in Figure 7.3, containing as many as 47 pins p0, p1, …, p46, where the ith pin is either active pi = 1, if present, or inactive pi = 0, if missing.

The breakwheel (rotated) counterclockwise or stepped from the current active pin to the next active pin causes the counterclockwise rotation of the RED's half-rotor. Irregular stepping of the RED results from the removal of some pins, at least four and at most six. Only the 11 pins p4, p5, p10, p11, p16, p19, p29, p30, p33, p38, p39 are removable. The rotor normally steps one position after the encipherment of a letter, but the breakwheel causes it to step k + 1 position if k consecutive pins are removed.

7.3.1 The Breakwheel and its Stepping Sequence

The rotor's position P(i) for the encipherment of plaintext letter xi is an integer P(i) with 0 ≤ P(i) < 47; it depends on the initial position P(0) of the rotor and the locations ...

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