The World War 2 German naval code Enigma, was broken at Bletchley Park, the center of major British Intelligence activities during WW2. But even if you are familiar with Enigma, you may have not heard about the much more complex machine cipher known as Tunny. This was the cipher used by Adolf Hitler himself and his top commanders to communicate with one another. Those who worked to break this cipher at Bletchley Park were prohibited from discussing it until the mid-1980s. The author is one of few living individuals with firsthand knowledge of the Tunny cipher. He was one of the young intelligence officers tasked with the project of breaking Adolph Hitler's personal encryption, an eyewittness to history, and arguably a history-maker himself. This is his memoir of the experience.