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To commemorate the 70th Anniversary of the mathematical breaking of the Enigma cipher machine in Poland, I have now released my Polish Enigma Simulator from my archive. This computer simulator is for Windows 3.1 - 2000 (not yet tested on XT). It is fitted with Drums I-V and Reflectors (UKW) A and B. Note that Polish wiring for Drums IV and V had an additional offset of 1 and 2 respectively between the wired core and a reference frame. It was not possible to determine point A on these Drums since the wiring was recoved cryptanalytically without any keying documents. Drums I - III were labelled correctly on recovery by cryptanalysis since the daily Grundstellung and Ringstellung was given in the Asché documents. However to avoid any possible confusion, the Drums presented here are exactly as those used by the German armed services.
The simulator is based on the machine at the Sikorski Institute in London, which is not operational and has several wires missing in the drums. (Reflector A was taken out of service in 1937 so would probably not have been used in this particular machine, which is assumed to have be built after 1939)

Reflector A appears here in a simulator for the first time.
For details of this reflector see:
Marks, Philip and Frode Weierud. 2000. Recovering the Wiring of Enigma's Umkehrwalze A. Cryptologia 24(1) 55-66.

The offsets of Drum IV and V was recently re-discovered by Philip Marks.
For details see:
Hamer, David H., Geoff Sullivan and Frode Weierud. 1998. Enigma Variations: An Extended Family of Machines.
Cryptologia 22(3) 211-229.

Background history

Marian Rejewski, Jerzy Rozycki, Henryk Zygalski and other cryptoanalysts from BS4, broke into Kriegsmarine code in November 1932.
By the end of December 1932 Reichswehr Enigma code was partly broken by Marian Rejewski
Fully decrypted Enigma texts were read by BS4 since mid January 1933.
During Roehm's Putsch in June 1934 Enigma messages were read within minutes from their interception.
During two weeks long cryptographic exercises organised at BS4 in January 1938 up to 75 percent of secret German communication was decrypted within hours from interception.
Wehrmacht correspondence was decrypted as efficiently up to November 1938 and Sicherheitsdienst up to 1st July 1939. Once Chi-Dienst upgraded German Enigmas BS4 lost its possibilities and between November 1938 and Summer 1939 only one in ten Wehrmacht despatch was read.
In July 1939 BS4 shared its secrets with GC&CS and cypher section of the French SR.
In October 1939 evacuated from Poland BS4 codebreakers resumed their work in France as Equipe Z
On 17th January 1940 Equipe Z as the first Allied codebreaking team broke wartime Enigma daily key and immediately passed its findings to Bletchley Park. Bletchley Park began its mass codebreaking work.
Equipe Z was active until November 1942 when Wehrmacht occupied Vichy and German RDF vehicles were spotted near its premise. In total Poles decrypted Enigma cypher for ten years from December 1932 until November 1942.
Polish Enigma Simulator can be downloaded Here.
(Windows 3.1/95/98/NT4/2000)