ENCYCLOPEDIA OF Espionage, Intelligence, and Security Volume ...

BombeJoe Desch, shown in 1943, headed a top-secret program at the NationalCash Register Co. in Dayton, Ohio, to develop a high-speed decipheringmachine called a Bombe, used to crack the Nazi submarine code. AP/WIDEWORLD PHOTOS.Park against the German Enigma cipher, could break messages72 times faster than the first Pentium computer.The bombe derived its name from the loud, rhythmic,and somewhat ominous ticking noise it made while computingcode permutations. The machine itself was highlycomplex, requiring skill in mathematical code breakingand engineering to construct. Throughout World War II,the form of the bombe changed many times. Each improvementadded to the machine’s ultimate effectivenessand efficiency.Enigma and the development of the bombe. Most ofGermany’s high-level military messages were encodedusing a cipher machine called Enigma. The complex codeused not only a cipher, but also an overlaying encryptionto disguise the original text. The series of rotor wheels onthe Enigma teleprinter gave the machine an extraordinarynumber of code combinations. The Germans were confidantthat the machine code was perfectly random, andtherefore mathematically unbreakable. However, both Polishand Swedish intelligence made significant progressbreaking Enigma even before the outbreak of World War II.In the months preceding the German invasion ofPoland in 1939, Polish intelligence gave British intelligenceinformation on their efforts to break Enigma. MostEncyclopedia of Espionage, Intelligence, and Securityhelpful was the information Polish spies gathered on howthe cipher machine operated, including sketches of theteleprinter and some of its components. The Poles alsoincluded blueprints for a code-breaking device that theyhad not yet been able to construct, the first bombe decoder.At the time the Poles broke Enigma using longhandmathematics, the Enigma machine had only three rotors.On the eve of war, the Germans replaced most of the threerotor machines with new a new five rotor model, makingEnigma more difficult to break, and sending British engineersback to the drawing board to redesign the bombe.Before the mechanical device could be designed andconstructed, however, Bletchley Park cryptologists had tobreak the new version mathematically. With the informationprovided by Polish intelligence, Bletchley Park cryptologistsfound two key weak links in the Enigma code.Enigma code prohibited that any letter be encrypted asitself, and German standards of diplomatic communicationdictated that the same phrase begin many transmissions.Exploiting these two weaknesses, British cryptologistsbroke Enigma in 1940. Within a year, they had brokentwo other major German codes, including the perplexingLorenz cipher used by Hitler’s High Command. BletchleyPark engineers then set out to adapt original bombe designsto operate against the new codes.British engineer Alan Turing designed and constructedthe first successful bombe. The Turing Bombe, or “Tabs,”as it became known, operated against the German Enigmacode, but could be adapted to decipher other codes. TheTuring Bombe was the main device used against Enigma,but its complex operation required the work of severaloperators. During the course of the war, women were thepredominant operators of Bletchley Park bombes, decodingand translating intercepts for intelligence service use.Even with the operation of several bombes, Enigma interceptinformation could not be used in “real time” butmilitary field command or forward intelligence units. Aseries of improvements aided computational time, includinga diagonal switchboard and “machine gun” voltageregulator, which were added to eliminate processing errorsthat stopped the bombe’s computation. A teleprinterwas added to the device to allow for simultaneous transcriptionof messages into the original German, ready fortranslation.British intelligence shared some of their cryptanalyticwork with United States forces, even before the U.S.entered the war in 1941. However, after the bombing ofPearl Harbor, President Roosevelt acknowledged that thecryptanalytic efforts of military intelligence needed additionalaid. Some Bletchley Park personnel went to Americato train new code breakers, most of whom were membersof the Women Accepted for Voluntary Emergency ServiceCorps (WAVES). WAVES assembled and trained to operatevarious bombes, eventually producing 121 bombes forused against seven different Japanese and German codes.After the Germans began sharing Enigma code secretsand teleprinter construction secrets with the Japanese in1942, U.S. intelligence became more able to decipher137