Decryption

How Decryption Helped Beat The Nazis, And What It Means For Infosec Today

During World War II, the Allied powers intercepted huge volumes of radio communications being used by the Axis powers to coordinate military activity. Many intercepted messages had been encrypted using the most sophisticated algorithms available at the time, and the encryption keys were changed as frequently as every day. Because Allied codebreaking and decryption efforts were too slow in the early years of the war, cracking those codes yielded information that became irrelevant almost as soon as it was gleaned.

Nonetheless, the Allies were able to derive useful information about the timing, location, and scale of Axis operations by tracking metadata about the transmissions. By triangulating transmissions via High Frequency Direction Finding (HF/DF) and cross-referencing their volume and number against the call signs of transmission stations, Allied forces could locate where enemy forces were assembling, and even infer the order of battle expected for specific engagements.