Herbert Osborne Yardley

As a young man, the American Herbert Yardley (1889-1958) gained a reputation for his ability to break codes used by the US State Department , where he worked as an ordinary clerk. After the outbreak of World War 1 he was commissioned into the US Army and put in charge of the newly formed cryptography section of Military Intelligence (MI8). He devised new codes for use by the US Army and helped to convict a German spy whose secret message had been decoded by MI8.

After the war, Yardley established a permanent department, the American Black Chamber, to assist both the State Department and Milirat Intelligence with all code and cipher work. Yardley's greatest success came when his cryptography group broke secret Japanese codes, which enabled the United States to gain significant advantages at the international naval disarmament conference of 1921. [Extracted From Ultimate Spy]