British - Bombe

"The geese who laid golden eggs and never cackled." - Winston Churchill.

Build on the Poles

England continued the cryptanalytic work that the Poles had begun. The Government Code and Cipher School, GC&CS, like the Poles, hired many mathematicians, some of them being Alan Turing and Gordon Welchman. Bletchley Park was chosen because of its vastness for potentially housing many people and resources required for code cracking. In early September 1939, at Bletchley Park, the new home for these mathematicians during World War II, work intensely began. Despite the great many configurations of the Enigma machine, cryptanalysts at BP were able to capitalize on various human errors that greatly reduced the number of possibilities. For instance, when communicating right in the middle of battle, operators had to quickly, without much though, enter their keys and one way of doing this was to enter 3 consecutive keys in a row, say QWE. Another example was the pre-assignment of the rotor settings. No rotor settings could be the same for 2 consecutive days. Additionally, a letter in the plugboard could not be paired up with a letter right next to it.

Turing

Born in 1912, Alan Turing went to King's College, Cambridge, a Mecca of Intellectuals, in 1931. It was a crucial time in mathematics, because the ironic questioning of the absoluteness of mathematics was being debated, i.e. Kurt Godel's theory of undecidability of whether or not every and all math questions could be answered. Because Turing was so immersed in this work, it was then that Turing produced his most genius mathematical paper, "On Computable Numbers", in 1937. Although, it did not provide an answer to Godel's theory, it led to the Turing Machine, which was ahead of its time because it laid the foundation for the modern day programmable computer as we know it today. To view more about computation visit: bletchleypark.net/computation. To view more about Alan Turing view: alanturing.net.

However, Turing's genius did not stop there. Immediately, in 1939, he was recruited by the GC&CS at BP. Turing took advantage of all the decrypted messages that accumulated at BP, by predicting parts of a ciphered text with a little more accuracy. A nightmare to security is patterns and structure and one example of this was the German's weather reporting every day at 6 am. The German word for weather is "wetter", of which with a fairly certain degree of probability, could exist in a message. This guess of an association of plaintext with ciphertext, is known as a crib. This was Turing's first angle of attack, having a crib that could have nothing to do with the plugboard so as to reduce the number of rotor setting possibilities to check. Then after finding the correct rotor settings the plugboard arrangement could be deduced. As a matter of fact, cribs became so important that the military on occasion engaged the Germans in such a way to seed information by invoking them into sending a predictable message. For instance, mines would be laid in a certain area near a German vessel. This vessel would then radio map coordinates to other German vessels. After the intercept, the cryptanalysts at BP would know ahead of time some of the contents of the message because they know where the mines have been laid.

Because of Turing's brilliance using patterned loops, which were similar to Rejewski's patterned links, from cribs and connecting multiple Enigma machines to run in parallel, officials at BP came up with a significant sum of money to implement Turing's idea at the beginning of 1940. Turing's plan were very similar to the Polish Bomba, however, instead it would examine all possible Enigma configurations that could possibly match plain text to its counter cypher text instead of trying to obtain the rotor configuration. Various senior cryptanalysts throughout the park heard about this amazing feet, thus praised and more so respected Alan Turing as one of the best codebreakers known.

Welchman

Gordon Welchman greatly assisted Turing by expanding the plugboard wiring by connecting each letter to all the other letters because normally the plugboard connected one letter to a second letter thus causing the the second letter to connect back with the first letter on the rebound. This was called the diagonal board. Turing and Welchman then integrated their design and had Harold "Doc" Keen, an engineer with the BTM, British Tabulating Machines, build a cryptanalytic electromechanical device called a Bombe (the French name of the Polish Bomba). In August 1940, the machines were finally built after many months of work.

Bombe

WRENS

The Women's Royal Naval Service would operate the Bombes and report any positive results to cryptanalysts. When the Bombe found a match it would stop and the operator would know to write down the rotor settings. So when the cryptanalysts ran across that correct setting they let the WRENS know to stop working on the current message and work on another one. This procedure on average took about 45 minutes total, 10 minutes to change the order of the wheels for the subsequent run and 35 minutes for the rotor positions and connections set up.

German Navy

All of this was fine and well with the Luftwaffe and the German Army because of their lack of formality and rigor in their communication security. However, the German Navy, used a very rigid process for communication and also had a total of 8 rotors to choose 3 from and thus making it too difficult for the British to break codes. The United States although neutral at the time, provided resources and materials to Great Britain via a North Atlantic supply line. However, the U-boat fleet, commanded by Admiral Doenitz of Germany, was wreaking havoc on the ally convoys. Once a convoy was spotted Enigma enciphered radio traffic alerted other U-boats to join the slaughter like a pack of wolves. It seemed as though Germany was winning the war in the Atlantic.

Breakthrough

After 21 months of being left in the Atlantic dark, on May 1941, Britain captured U-boat, U-110. Most importantly and luckily the Enigma machine and other relevant documents were compromised. The crew had abandoned ship too quickly to destroy the Enigma machine in fear of drowning. So within a very short time, after all of the pertinent information was shipped to Bletchley Park and thus German Navy codes were now being read at a favorable rate. To help matters even further, Doenitz assumed that U-110 sunk along with all important encryption material and did not bother changing the anything. However, in the fall of 1941 Doenitz, began to see the shift and toll that his U-boat fleet was taking and then became suspicious that the Allies were breaking Enigma encoded messages. He confronted the German command but was reassured that with Enigma's possibilities it would be impossible to break.

"Ultra" Disguise

Information such as the time and location of bombing raids, the number of Luftwaffe planes in an attack and so forth would be sent to MI6, and then from there forwarded on to the appropriate military commands in the war cabinet, such as the Admiralty and the Air Ministry, to organize plans. The British went to great lengths to disguise their knowledge of specific German military operations. When an Enigma encoded message was cracked, they would quickly scramble reconnaissance aircraft in the area where possible to make it appear that the Germans were spotted.

However, at times this grew difficult to do. For instance, an intercept that was cracked at BP showed the locations of 9 German Navy tankers and thus the British military command wanted to only sink 7 of them and intentionally letting 2 go free. The British destroyers only knew enough information of the 7 tankers, that guided them into the vicinity. When the British destroyers engaged them, sure enough the 7 German tankers were sunk. However, the destroyers quickly ran into the other 2 that were supposed to go free, identified them and then sank them as well. The British battleships, of course, were not aware of Enigma and the intention of keeping code cracking operations a secret.

Another event worthy of notice that demonstrated the organization of security was, because only the British high command starting with Winston Churchill managed every possible operation, the code crackers at BP didn't even know how their information would be used exactly. A case in point was the D-Day, Normandy invasion that took place later on in June, 1944. Only the military head at BP, Commander Edward Travis, knew about this during the moment. Members of Hut 6 threw a dance the night before the landings, which rattled Commander Travis but he could not let them know for security reasons. Perhaps, the intellectuals at BP might have had an idea but they did not know for sure. So, all of these and various other drastic measures had to be taken so that German suspicions could be kept as minimal as possible.

German Navy Again

Finally, Admiral Doenitz had the Enigma machine strengthened. An additional rotor was added to the machine itself. Even though Bletchley Park had mapped the wiring of the fourth rotor they still were behind in trying to crack Enigma encoded messages. Britain referred to the new code that was also reinstated as the "Shark," thus Britain had to redesign the Bombe because as it was, it could not arrive at the four rotor setting. Nevertheless, U-boats began sinking Ally ships in the Atlantic, once again. The first half of 1942 was the gloomiest point for the Allies. The U.S. just began a war with Japan sparked by the bombing of Pearl Harbor, the Russians were pushed all the way back to Moscow and Germany was at the door steps of invading England.