Germany:
During World War II, Germany possessed an advanced code-breaking organization called the "Chiffrierabteilung" within its military intelligence agency, the Abwehr. The Chiffrierabteilung focused primarily on deciphering codes used by various nations, including the Allied powers.
Enigma Decryption:
Germany's most notable achievement in code-breaking was deciphering the Enigma machine, a sophisticated cipher device employed by the German military and other government agencies. Polish mathematicians and cryptographers, notably Marian Rejewski, Jerzy Różycki, and Henryk Zygalski, made significant progress in breaking the Enigma codes in the 1930s.
However, the Germans enhanced the complexity of Enigma over time, making it increasingly challenging to break. It was not until the Allies acquired an Enigma machine and codebooks captured from a German U-boat in 1941 that they were able to consistently decrypt Enigma messages.
The British code-breaking facility at Bletchley Park played a crucial role in deciphering Enigma messages. By the latter stages of the war, the Allies could regularly decipher a large portion of German Enigma traffic.
Japan:
Japan also devoted considerable resources to cryptanalysis efforts, particularly through its Navy's "JN-25" code-breaking unit. Japan had some initial success in deciphering American diplomatic codes before the war and managed to break certain low-level military codes during the early stages of the conflict.
Purple Code:
Japan's most notable code-breaking achievement was the partial decryption of the American PURPLE code, a high-level diplomatic cipher used by the United States Department of State. Japanese cryptographers managed to decipher a portion of PURPLE messages, although their success was limited and sporadic.
However, the Japanese were unable to consistently break the PURPLE code on a large scale. The United States changed the PURPLE code several times during the war, further complicating Japan's efforts.
Significance:
While both Germany and Japan had some successes in code-breaking, these achievements were limited in scope and did not significantly impact the overall course of the war. The Allies gained a significant advantage by successfully deciphering German and Japanese codes, which played a crucial role in numerous military campaigns and strategic decisions.