Mike Thomson explores the implications of a secret CIA report made in the 1960s that suggested British and American diplomatic cables and reports were being decrypted by the Japanese with the help of an American Cryptologist.
He tells the story of the colourful founder of American Cryptology, Herbert O Yardley. Yardley's publication of a book explaining his cryptographic success, particularly against the Japanese was a cause celebre in 1931. However, new documents coming to light suggest that Yardleys work for the Japanese continued long after, and that he may have been involved in deciphering British and American diplomatic messages giving the Japanese a clear understanding of the lack of preparedness for the attacks on Pearl Harbour and Singapore.
Producer - Tom Alban.