Enigma Machine - Derivatives

Derivatives

The Enigma was influential in the field of cipher machine design, and a number of other rotor machines are derived from it. The British Typex was originally derived from the Enigma patents; Typex even includes features from the patent descriptions that were omitted from the actual Enigma machine. Owing to the need for secrecy about its cipher systems, no royalties were paid for the use of the patents by the British government. The Typex implementation of the Enigma transform is not the same as the transform found in almost all of the German or other Axis versions of the machine.

A Japanese Enigma clone was codenamed GREEN by American cryptographers. Little used, it contained four rotors mounted vertically. In the U.S., cryptologist William Friedman designed the M-325, a machine similar to Enigma in logical operation, although not in construction.

A unique rotor machine was constructed in 2002 by Netherlands-based Tatjana van Vark. This unusual device was inspired by Enigma but makes use of 40-point rotors, allowing letters, numbers and some punctuation to be used; each rotor contains 509 parts.

Machines like the SIGABA, NEMA, Typex and so forth, are deliberately not considered to be Enigma derivatives as their internal ciphering functions are not mathematically identical to the Enigma transform.

Several software implementations of Enigma machines do exist, but not all are state machine compliant with the Enigma family. The most commonly used software derivative (that is not compliant with any hardware implementation of the Enigma) is at EnigmaCo.de. Many Java applet Enigmas only accept single letter entry, making use difficult even if the applet is Enigma state machine compliant. Technically Enigma@home is the largest scale deployment of a software Enigma, but the decoding software does not implement encipherment making it a derivative (as all original machines could cipher and decipher).

On the other hand, there is a very user-friendly 3-rotor simulator here: http://w1tp.com/enigma/enigma_w.zip where users can select rotors, use the plugboard as well as defining new settings to the rotors and reflectors. The output is in separate windows which can be independently made "invisible" to hide decryption. A 32-bit version of this simulator can be found here : http://membres.lycos.fr/pc1/enigma

A more complex version is here: http://w1tp.com/enigma/EnigmaSim.zip which includes an "autotyping" function which takes plaintext from a clipboard and converts it to cyphertext (or vice-versa) at one of four speeds. The "very fast" option runs through 26 characters in less than one second.

There currently are no known open source projects to implement the Enigma in logic gates using either RTL or VHDL logic gate markup languages.

• A Japanese Enigma clone, codenamed GREEN by American cryptographers.

• Tatjana van Vark's Enigma-inspired rotor machine.

• Electronic implementation of an Enigma machine, sold at the Bletchley Park souvenir shop