M-325

The M -325 (or SIGFOY ) it was developed by William F. Friedman in 1936 in the United States rotor cipher machine. Between 1944 and 1946 1100 of these machines were used by the diplomatic service of the United States. 1946, the use of the M -325 was discontinued because they could not meet the expectations placed on them in terms of reliability and speed. Once submitted, by Friedman on August 11, 1944 patent for the M -325 was born on March 17, 1959 issued (U.S. patent # 2,877,565 ).

Operation

The operation of the M -325 was identical to Enigma in the core. The M -325 had like the Enigma three further back end during the encryption or decryption of rotors and a rear end not turning roll. As with the commercial variants Enigma reversing roller could also be set by hand in one of 26 positions. The mapped on M -325 does not have a plugboard in contrast to those used by the German armed forces Enigma variations. According existed but also a version with plug board.

The stepping of the three movable rotors was accomplished through the so-called transfer scores of the rotors. The rotors of the M -325 had five of such notches (see), whereas the rotor of the Enigma had only one or two grooves. Therefore, the movement of the rotors of the M -325 was much more irregular than the Enigma, which significantly complicated the unauthorized decoding. The rotor box shown on has nine compartments, suggesting suggesting that in addition to the reverse roller eight other rotors were available from which had to be three selected to operate the machine. From may further be concluded that the rotors of the M -325 could be used only in an orientation in the machine.

Operation

The output of the encrypted or decrypted character was as in the Enigma on a light box. Among the labeled with the letters of the alphabet lamps are buttons that had to be pressed when that character should be encrypted or decrypted were. After the encryption or decryption of each character, the operator had also press another button that triggered the further back of the rotors.