- WW2 RADIO SCRAMBLER CRACKED
- WW2 RADIO SCRAMBLER GENERATOR
- WW2 RADIO SCRAMBLER MOD
- WW2 RADIO SCRAMBLER SERIES
The records were played on turntables, but since the timing – the clock synchronization – between the two SIGSALY terminals had to be precise, the turntables were by no means just ordinary record-players. For testing and setup purposes, a pseudo-random number generating system made out of relays, known as the "threshing machine", was used. The records served as the SIGSALY "one-time pad", and distribution was very strictly controlled (although if one had been seized, it would have been of little importance, since only one pair of each was ever produced).
The record was then duplicated, with the records being distributed to SIGSALY systems on both ends of a conversation.
The noise values used for the encryption key were originally produced by large mercury-vapor rectifying vacuum tubes and stored on a phonograph record.
WW2 RADIO SCRAMBLER GENERATOR
WW2 RADIO SCRAMBLER MOD
For example, if the voice amplitude value was 3 and the random value was 5, then the subtraction would work as follows:ģ − 5 ≡ − 2, − 2 + 6 ≡ 4 ( mod 6 ) The subtraction was performed using modular arithmetic: a "wraparound" fashion, meaning that if there was a negative result, it was added to six to give a positive result.
WW2 RADIO SCRAMBLER SERIES
The pitch signal, which required greater sensitivity, was encoded by a pair of six-level values (one coarse, and one fine), giving thirty-six levels in all.Ī cryptographic key, consisting of a series of random values from the same set of six levels, was subtracted from each sampled voice amplitude value to encrypt them before transmission. This scheme, known as " companding" or "compressing-expanding", exploits the fact that the fidelity of voice signals is more sensitive to low amplitudes than to high amplitudes. The amplitude levels were on a nonlinear scale, with the steps between levels wide at high amplitudes and narrower at low amplitudes. For the band amplitude signals, the amplitude converted into one of six amplitude levels, with values from 0 through 5. Next, each signal was sampled for its amplitude once every 20 milliseconds.
WW2 RADIO SCRAMBLER CRACKED
Īlthough telephone scramblers were used by both sides in World War II, they were known not to be very secure in general, and both sides often cracked the scrambled conversations of the other. The Germans had a listening station on the Dutch coast which could intercept and break A-3 traffic. At the time of its inception, long-distance telephone communications were broadcast using the "A-3" voice scrambler developed by Western Electric.