LORENZ CIPHER BUST HISTORY

Cryptologia, Jan 2004 by Kruh, Louis

LORENZ CIPHER BUST HISTORY Cragon, Harvey G. From Fish to Colossus: How the German Lorenz Cipher was Broken at Bletchley Park. Cragon Books, 8600 Skyline Drive, #1102, Dallas TX 75243 USA. 2003. 146 pp. $25.00 ppd./£12.99 from Bletchley Park Trust book store.

The Lorenz cipher machine, an enciphered teleprinter system, was used by the Germans in World War II. It was limited to very high level communication links between Hitler's headquarters and various Army headquarters. When Bletchley Park became aware of these links, the code name Fish was given to the system. The first link identified was Tunny. The machine was called Schlusselzusatz or Cipher attachment. The two main models were SZ 40/42. The Lorenz had 12 wheels and worked on a system invented in America by Gilbert S. Vernon in 1918.

Unlike Enigma's substitution cipher, Fish messages were in an additive cipher derived from the machine generating a pseudo random stream of characters that were added to the plaintext. he thoroughly details the breaking of Fish by the British starting with an examination of the American patents, examines the work of individuals and Huts at Bletchley Park that contributed to the solution: Col. John Tiltman solved two messages, William Tutte succeeded in determining the design of the Lorenz machine, The "Testery" headed by Major RalphTester and the "Newmanry" headed by M. H. A. Newman made major contributions. C. E. Williams helped with the design of Robinson machines, which served as research and prototyping precursors to the Colossus. Newman spoke to Tommy Flowers at The Post Office Research Establishment about the need for a faster, more powerful machine. he agreed and subsequently developed the electronic solution that became Colossus. The author credits individuals for their contributions but mainly focuses on the electronic designs and details that led to success.

Cragon retired after 25 years at Texas Instruments where he designed and constructed the first integrated circuit computer and first TTL computer. He is a Professor Emeritus at the University at the University of Texas-Austin and recipient of an ACM/Fellow Award.