History of the cryptanalytic bombe

Cryptologia, Oct 2002 by Kruh, Louis

HISTORY OF THE CRYPTANALYTIC BOMBE

Solving the Enigma: History of the Cryptanalytic Bombe. Center for Cryptologic History, National Security Agency, 9800 Savage Road, Fort Meade MD 20795-6886 USA. 52 pp. Free.

Starting with a brief history of the Enigma cipher machine, the author describes how Polish cryptanalysts solved its ciphers. Subsequently, faced with the threat of the German invasion, they shared their secrets with the British. British mathematicians, Alan Turing and Gordon Welchman, sought quicker ways to solve German messages. Ultimately this led to development of the Bombe, which is described in some detail. The addition of a fourth rotor by the German Navy was catastrophic because British Bombes could not find settings for four rotors and German U-boats were sinking convoys loaded with much needed supplies destined for Britain.

At this point the United States began efforts to develop its own Bombes. And most of this publication is devoted to that work. The U.S. Navy contracted with the National Cash Register Company (NCR) in Dayton, Ohio to work on the development and construction of specialized machines and established the Navy Computing Machine Laboratory (NCML). NCR engineer, Joseph Desch, became NCML's research director and was the designer of the U.S. Navy Bombe.. His work was cloaked in extreme secrecy and it was decades after the war before his family learned of his work. Waves and sailors were sent to Dayton to construct the Bombes, e. g. over 6,000 rotors had to be wired. An 8-page appendix describes Cribs, Menus and Bombe Set-up. Another appendix compares Army and Navy Bombes. A terrific publication and its FREE.