Technical Articles

The following technical articles relating to the various machines are available for download.

The Abwehr Enigma Machine
 

This formidable cipher machine was ‘broken’ in 1941 by the distinguished cryptographer ‘Dilly’ Knox with the  assistance of two young women from his section (known as ‘ISK’ - Intelligence Services Knox). The article gives an outline account of how it was done.  download

From Bombe Stops to Enigma Keys

Created : 21 June 04, Size : 153.6 Kb
A commonly held belief concerning the Bombe is that it was a machine that was used for the automatic recovery of Enigma message keys. This rather simplistic view is very far from the truth and the attached article explains some of the reasons why. download

Rodding

Created : 21 June 04, Size : 286.72 Kb
The technique of 'Rodding' was invented by 'Dilly' Knox in 1937 at the time of the Spanish Civil War. Together with some special German ciphers (Abwehr) it later enabled the breaking of some very important Italian Navy Enigma messages. download

Buttoning Up

Created : 21 June 04, Size : 204.8 Kb
One of the fundamental problems confronting the pre-war staff of GC & CS was to find the internal wiring of the Enigma rotors. These notes describe a method devised in 1936 by the veteran cryptographer Dillwyn Knox, in which he used a procedure he referred to as 'buttoning up'. In 1937, by means of this method, Knox succeeded in recovering the wiring of the rotors used by the Italian Navy in their Enigma machines (this work paid handsome dividends later on in 1940/41). This is a companion article to Rodding, which should be read first. download

Breaking of the Lorenz Cipher

Created : 22 September 04, Size : 92.16 Kb
The breaking of the Lorenz cipher at Bletchley Park was a remarkable synergy of mathematics and engineering that had a significant effect on the course of WWII. download

A Polish Triumph

Created : 29 March 05, Size : 143.36 Kb
The discovery of the internal wiring of the rotors in the military version of the Enigma was the greatest of the pre-war achievements made by the Polish mathematician Marian Rejewski. This article gives a full account of how it was done. download