Codebreaking In Ww2

The ever evolving method of cryptography, or sending messages through code, can be traced throughout the history of the world. Early Egyptians communicated through mysterious hieroglyphics. Ancient Greeks concealed secret messages beneath wax on tables or with tattoos on a slave’s head. During the Renaissance in Europe, citizens would use a substitution cipher to carry messages about political and religious revolutions. During World War I and previous battles, most countries used codes to contact their navy or army branches abroad, in case of enemy interception. Which subsequently brings us to World War II, and the major role that codebreaking played in the results of the war. Some of the main codebreaking events during World War II, the breaking

of the German Enigma and the breaking of the Japanese code, were two of the strongest turning points for the Allied victory. Without the intelligence produced from cryptanalysis, the war would’ve lasted much longer with many more casualties, and machines today would not have been evolved.
The cryptanalysts at Bletchley Park disregarded all skeptic thoughts and broke the code that would later change the course of World War II. Before Poland fell, they shared their previous progress on the German Enigma, with Bletchley Park in England, which became the home base for World War II codebreakers. Enigma was the most advance ciphering device of its time. It encoded messages via an electromechanical system incorporating moving wheels or rotors. A character typed on the keyboard was sent through the rotors electrically and the code equivalent read off an illuminated panel. The rotors change their relative positions during encipherment to scramble the pattern a codebreaker looks for. The cipher circuits also went through a plug boar which switched letter pairs. Rotor and plug board configurations were changed at regular intervals. The codebreakers task was to identify the start positions of the rotors and unravel the plugboard setup. The Germans used Enigma because they believed that “the key could not be found, since it is impossible to run through 6 billion (seven rotors) or 100 trillion (thirteen rotors) keys [rotor starting positions].” (Gladwin, 204). But this impossible problem intrigued British mathematician Alan Turing even more. Using intelligence provided by Poland and Turing’s brilliant mind, he concluded that a “universal machine might be devised that could imitate any other” (Gladwin, 209). And so that is what Turing did, he ended up creating the standard British bombe. This machine contained 36 Enigma equivalents, each with three drums wired to produce the same scrambling effect as the Enigma rotors. A bombe could run two or three jobs simultaneously. Since “wartime code breaking was of course a life and death matter, speed was everything” (BBC Horizon, 24:10-24:20), the new machine was a perfect way to decipher the often intercepted German codes. As early as 1943 Turing's machines were cracking a staggering total of 84,000 Enigma messages each month, which was equivalent to two messages every minute. The decryption of the Enigma, which was present on all German u-boats, allowed the Allied forces to know mission details like locations, times, and destruction level. Winston Churchill, the Prime Minister of Great Britain at this time, said that “the only thing that ever really frightened me during the war was the u-boat peril.” By saying this he is referring to the constant torpedoing of American supply boats that were being shipped to Britain. Turing’s brilliant discovery couldn’t have come at a better time for the Allied forces.
The cryptanalysis at Station HYPO used breaking of code to defy orders and many opinions, in order to predict the second Japanese attack. After the attack on Pearl Harbor, the US Navy was on high alert. Officer Joseph Rochefort, who was also a cryptologist and engineer, was put in charge of HYPO and spent hours decrypting thousands of Japanese codes. Unlike the Enigma code, which was machine generated, the Japanese used book ciphers for their naval codes. Book ciphers work through the sender composing his message and then consulting the code book. Common words and phrases are replaced with a group of numbers and letters, and any remaining text is encoded character by character. The result is transmitted and the receiver then looks up each group in the corresponding code book and reassembles the message. This code, named JN-25B, used “50,000 5 digit different code groups” disguised through super encipherment “by additives of 55,000 more” (Carlson, 25:35-25:55). The decoding of this code consisted of “pencil and paper” problem solving “one at a time” (Carlson, 26:35-26:45). Each month they use three million IBM punch cards to store and retrieve naval codes. Gradually a usable portion of the JN-25 became readable, which hinted towards a major offensive towards the US. Locations from the decrypted code book pointed towards the location, disguised as “AF”, to be Midway Island. But other naval intelligence organizations, particularly ones in Washington disagreed on the location and timing. But Rochefort and his comrades were strong in their beliefs, and went forward in misleading the Japanese, “despite claims from Washington intelligence officials that it could not be done” (McDowell). Many naval officials didn’t believe in the power of cryptology, and thus doubted the intelligence it could acquire. But wanting to prove themselves, Rochefort and his team planned a clever experiment to confirm Japan’s target.
Pearl Harbor and Midway Island were connected by an underwater cable that was invulnerable to Japanese interception.

Station HYPO sent orders to Midway by cable to broadcast a radio message that the island's water plant had broken down. The radio message was broadcast without encryption to ensure that Japan could read it if it was intercepted. The radio message was indeed intercepted by Japan and then reported by a message encoded in JN-25 stating that “AF’s” desalination plant was out of order. That message was intercepted by Station HYPO, and “AF” was thus confirmed as Midway. Station HYPO concluded that the attack would come in late May to early June 1942, while Washington argued late June. Station HYPO's intelligence persuaded US Pacific Fleet Commander Nimitz to risk the three remaining US carriers in the Pacific in an attempt to ambush the Japanese attack on Midway, which turned successful by sinking four Japanese carriers. Station HYPO won out again because they had succeeded in cracking JN-25, and later put “cryptanalysis on the map for military, it gave codebreakers the respect and reliability when they needed it the most.” (Carlson, 35:10-35:30). The intelligence that HYPO was able to gather and put into action helped change the course of the Japanese

offensive.