by Morley Evans
One of the best-kept secrets of the Second World War
To this day, the official story is that the Japanese taskforce sailing to bomb Pearl Harbor kept strictly silent to avoid detection and that the attack came as a complete surprise to the American President.
According to Stinett, only General Short and Admiral Kimmel were in the dark. They had been set up by President Franklin Delano Roosevelt and Admiral King to take the fall. Pearl Harbour was bait in the trap that had been set for Japan.
The British were kept in the dark too along with General Douglas MacArthur in the Philippines. General MacArthur was not "in the loop." MacArthur was Army. Great Britain and its empire was history.
The Germans knew that one of Japan’s codes had been broken. They informed Japan and Japan just didn’t believe them.
The Type B Cipher Machine was introduced by Japan in 1938 and was code-named PURPLE by the US Signals and Intelligence Service (SIS). William F. Friedman, who worked for the SIS, would be the man to break the code.
Bust of Friedman in The National Cryptologic Museum in Maryland.
However, he and his colleagues didn’t just break the poor code, they eviscerated it. They were able to build a functional replica of the Type B Cipher without ever seeing a real one.
|“Fake” Type B Cipher machine|
Type B was used for diplomatic messages. America could now listen in to what the government of Japan told their diplomats and vice versa; a powerful tool during a time when the US was vying with Japan for dominance in the Pacific. It also provided information on the German military.
During World War II, the Japanese ambassador to Nazi Germany, General Hiroshi Oshima was well-informed on German military affairs. His reports went to Tokyo in Purple-enciphered radio messages. Examples include a comment that Hitler told him on June 3, 1941, that in every probability war with Russia cannot be avoided. In July and August 1942 he toured the Russian front and in 1944 the Atlantic Wall fortifications against invasion along the coasts of France and Belgium, and on September 4 that Hitler told him that Germany would strike in the West, probably in November. Since these messages were being read by the Allies, this provided valuable intelligence about German military preparations against the forthcoming invasion of Western Europe. He was described by General George Marshall as "our main basis of information regarding Hitler's intentions in Europe".
So how did the Germans get wind of this? Well, there seem to be two stories.
According to Francis Pike in Hirohito’s War, it was due to “British sloppiness” in 1941. The Germans had broken the British diplomatic code and some of the material deciphered suggested that the US was reading Japan’s diplomatic messages. The Germans passed on their suspicions but they simply were not believed.
The second version of events comes from the Wikipedia page for the Type B Cipher (linked above). This time, the Soviets take the blame.
In April 1941, Hans Thomsen, a diplomat at the German embassy in Washington, D.C., sent a message to Joachim von Ribbentrop, the German foreign minister, informing him that "an absolutely reliable source" had told Thomsen that the Americans had broken the Japanese diplomatic cypher (that is, Purple). That source apparently was Konstantin Umansky, the Soviet ambassador to the US, who had deduced the leak based upon communications from Sumner Welles. The message was duly forwarded to the Japanese, but the use of the code continued.
Regardless, Imperial Japan continued to use the Type B Cipher throughout the war believing it to be unbreakable.
ULTRA BROKE ENIGMA
|German Enigma code machine|
Up until the British managed to completely decrypt it, this device here was a nightmare for the Allies.
The Enigma machine is an encryption device that would scramble any text written with it in accordance to the machine’s settings. They look like gibberish when written, but when it runs through another machine with the same settings, they become the location of every ship in the Atlantic and every German offensive.
Only problem was, Enigma had 159,000,000,000,000,000,000 (159 billion, billion) possible settings.
This encryption code was nearly unbreakable, if not for a slip-up on part of the Germans’ nationalistic ideals. Regardless, for a machine that would take 20 million years to check up all the settings, the Germans were very confident with it.
It was just unthinkable back then that anyone would be able to guess 159 billion, billion different solutions.
Then, this man showed up.
The mathematician Alan Turing led the British Enigma decryption effort at Bletchley Park. At Hut 8, amongst the most significant contributions that Turing gifted the Allies was a significant improvement to the Polish bomba kryptologiczna machines, which played a pivotal part in breaking Enigma.
This machine is the Bombe.
|Bombe museum rebuild|
The Bombe was designed to crack the Germans’ Enigma settings, reducing 20 million years’ work to around a few hours to just under an hour or so. This was yet to be successful, but by 1941, Turing discovered a critical error within the Germans’ messages: at the end of every transmission were two words that helped the Allies save 14 million lives and ended World War II by 1945 instead of 1947,
Because of this phrase’s repetitiveness, the men and women at Bletchley Park were finally able to decipher Enigma’s daily settings at a substantially faster rate, allowing the British to stay one step ahead of Germany.
But the problem was, what if the Germans found out?
Well, that’s a relatively simple question to answer. The Germans would immediately change the design of Enigma, or scrap "Heil Hitler" from their messages, and just 6 hours after finding out that the British were peeking into their Enigma flow, the Germans would be back with a genuinely unbreakable code this time.
And this time, the Allies would be all but helpless.
And this is where Ultra comes in.
In order to divert the Germans’ attention from the possibility that Enigma had been breached, the Allies created a fake intelligence ring that gave the impression of being very well-placed deep behind enemy lines. This intelligence ring, later codenamed ULTRA, helped lead the Germans into thinking that these phantom agents were responsible for all of the offensives where the British easily countered a planned German attack. The Germans never suspected there was an Alan Turing along with his Bombe at Bletchley Park. The Germans looked for something that never existed. That is counterintelligence (MI-6) at its finest.
Conclusion: the Germans didn’t know they were being spied on because of ULTRA and they didn't redesign ENIGMA. They did add a set of wheels, however, increasing what was believed to be unsurpassable complexity. That was decoded too.