From: Gregory Neven Subject: Re: how does Enigma work? Date: Thu, 01 Feb 2001 17:12:29 +0100 Newsgroups: sci.math Summary: The Enigma encryption system from WWII Hi, This is a citation from Bruce Schneier's "Applied Cryptography": In the 1920s, various mechanical encryption devices were invented to automate the process of encryption. Most were based on the concept of a rotor, a mechanical wheel wired to perform a general substitution. A rotor machine has a keyboard and a series of rotors, and implements a version of the Vigenčre cipher. Each rotor is an arbitrary permutation of the alphabet, has 26 positions, and performs a simple substitution. For example, a rotor might be wired to substitute “F” for “A,” “U” for “B,” “L” for “C,” and so on. And the output pins of one rotor are connected to the input pins of the next. For example, in a 4-rotor machine the first rotor might substitute “F” for “A,” the second might substitute “Y” for “F,” the third might substitute “E” for “Y,” and the fourth might substitute “C” for “E”; “C” would be the output ciphertext. Then some of the rotors shift, so next time the substitutions will be different. It is the combination of several rotors and the gears moving them that makes the machine secure. Because the rotors all move at different rates, the period for an n-rotor machine is 26n. Some rotor machines can also have a different number of positions on each rotor, further frustrating cryptanalysis. The best-known rotor device is the Enigma. The Enigma was used by the Germans during World War II. The idea was invented by Arthur Scherbius and Arvid Gerhard Damm in Europe. It was patented in the United States by Arthur Scherbius [1383]. The Germans beefed up the basic design considerably for wartime use. The German Enigma had three rotors, chosen from a set of five, a plugboard that slightly permuted the plaintext, and a reflecting rotor that caused each rotor to operate on each plaintext letter twice. As complicated as the Enigma was, it was broken during World War II. First, a team of Polish cryptographers broke the German Enigma and explained their attack to the British. The Germans modified their Enigma as the war progressed, and the British continued to cryptanalyze the new versions. For explanations of how rotor ciphers work and how they were broken, see [794,86,448,498,446,880,1315,1587,690]. Two fascinating accounts of how the Enigma was broken are [735,796]. These are the relevant references: 1383. A. Scherbius, "Ciphering Machine," U.S. Patent #1,657,411, 24 Jan 1928. 794. D. Kahn, The Codebreakers: The Story of Secret Writing, New York: Macmillan Publishing Co., 1967. 86. W.G. Barker, Cryptanalysis of the Hagelin Cryptograph, Aegean Park Press, 1977. 448. C.A. Deavours and L. Kruh, Machine Cryptography and Modern Cryptanalysis, Norwood MA: Artech House, 1985. 498. W. Diffie and M.E. Hellman, "Privacy and Authentication: An Introduction to Cryptography," Proceedings of the IEEE, v. 67, n. 3, Mar 1979, pp. 397-427. 446. C.A. Deavours, "The Black Chamber: A Column; How the British Broke Enigma," Cryptologia, v. 4, n. 3, Jul 1980, pp. 129- 132. 880. A.G. Konheim, Cryptography: A Primer, New York: John Wiley & Sons, 1981. 1315. R.L. Rivest, "Statistical Analysis of the Hagelin Cryptograph," Cryptologia, v. 5, n. 1, Jan 1981, pp. 27-32. 1587. G. Welchman, The Hut Six Story: Breaking the Enigma Codes, New York: McGraw-Hill, 1982. 690. B.C.W. Hagelin, "The Story of the Hagelin Cryptos," Cryptologia, v. 18, n. 3, Jul 1994, pp. 204-242. 735. A. Hodges, Alan Turing: The Enigma of Intelligence, Simon and Schuster, 1983. 796. D. Kahn, Seizing the Enigma, Boston: Houghton Mifflin Co., 1991. cu Gregory mirek zywert wrote: > G'Day All ! > > Do you know guys, where on the net I could find some good pages, which > explain how the coding machine - Enigma works? > > Cheers, > mirek > map@alphalink.com.au ============================================================================== From: "Maciek Przybyła" Subject: Odp: how does Enigma work? Date: Thu, 1 Feb 2001 18:39:21 +0100 Newsgroups: sci.math Maybe you should ask at the university, where Enigma code was broken: http://www.wmid.amu.edu.pl/welcome.html.en Maciek Przybyla http://www.polsl.gliwice.pl/~mathew Użytkownik mirek zywert w wiadomooci do grup dyskusyjnych napisał:3A797EC4.2FBCB686@alphalink.com.au... > G'Day All ! > > Do you know guys, where on the net I could find some good pages, which > explain how the coding machine - Enigma works? > > Cheers, > mirek > map@alphalink.com.au >