UMKEHRWALZE D: ENIGMA'S REWIRABLE REFLECTOR - PART I

Abstract

Umkehrwalze D was a field-rewirable reflector for the German service Enigma machine, introduced primarily on German Air Force cipher networks late in the Second World War. The three parts of this article discuss the history of the device and the various techniques and machines developed by the wartime British and American signals intelligence agencies to deal with it.