In cryptography, Fialka (M-125) is the name of a Cold War-era Soviet cipher machine. A rotor machine, the device uses 10 rotors, each with 30 contacts along with mechanical pins to control stepping. It also makes use of a punched card mechanism. Fialka means "violet" in Russian. Information regarding the machine was quite scarce until c. 2005 because the device had been kept secret. Fialka contains a five-level paper tape reader on the right hand side at the front of the machine, and a paper tape punch and tape printing mechanism on top. The punched-card input for keying the machine is located on the left hand side. The Fialka requires 24 volt DC power and comes with a separate power supply that accepts power at 100 to 250 VAC, 50–400 Hz by means of an external selector switch. The machine's rotors are labelled with Cyrillic, requiring 30 points on the rotors; this is in contrast to many comparable Western machines with 26-contact rotors, corresponding to the Latin alphabet. The keyboard, at least in the examples of East German origin, had both Cyrillic and Latin markings. There are at least two versions known to exist, the M-125-MN and the M-125-3MN. The M-125-MN had a typewheel that could handle Latin and Cyrilic letters. The M-125-3MN had separate typewheels for Latin and Cyrilic. The M-125-3MN had three modes, single shift letters, double shift with letters and symbols, and digits only, for use with code books and to superencrypt numeric ciphers. Encryption mechanism The Fialka rotor assembly has 10 rotors mounted on an axle and a 30 by 30 commutator (Kc 30x30). The commutator consists of two sets of 30 contact strips set at right angles to each other. A punched card is placed between the two sets of contacts via a door on the left hand side of the unit. Each punched card has 30 holes, with exactly one hole per row and column pair, and thereby specifies a permutation of the 30 rotor contact lines. This feature is comparable to the plug board on the Enigma machine. A triangular plate was used to enter the null permutation for testing purposes. There are two types of rotors: disassemblable (zerlegbar) rotors, used with the M-125-3MN. The rotorset name is "PROTON." The disassemblable rotors consist of an insert with electrical contacts and scramble wiring, and an outer ring with mechanical pins whose presence or absence