The Enigma Collection


The Enigma Collection is meant to be a Web portal for information about the German cipher machine Enigma in all it variations. In the beginning this Web page should be seen as a kind of note board where I post information when my time and energy allows me to do so. Later on, the page hopefully will take on a more definitive form and perhaps it will even be more pleasing to the eye. For the time being the most important issue is to have a place where I can publish my Enigma notes. At the moment I am working on a detailed history of the Enigma and when this will be published, hopefully next year, I plan to publish here many of my research notes and other documents.


Discover How the Enigma Really Works

By first watching this brilliant YouTube video made by Jared Owen Animations of how the Enigma machine actually works you will have much better understanding of the other material posted on the page.

Enigma Publications

Here are some of our Enigma related publications from Cryptologia:

Historical Documents

Here are some more historically oriented papers.

Graham Ellsbury has published an impressive collection of historical and cryptanalytical reports. Here is a selection from his
The Enigma and the Bombe page:

Catalog of Enigma Cipher Machine Wirings

The Catalog of Enigma Cipher Machine Wirings compiled by Astrid Hammarborg of the National Security Agency, Technical Information Division, Bibliographic Research Branch in June 1954 was released to me on 26 September 2007 with only one major redaction. The release was in response to my FOIA request of 28 October 2004, FOIA Case 44559.

It is worth repeating the report's Introduction here to make it clear that the report contains a lot of raw data copied from work sheets and other scattered notes. This means that some of the machine wirings are duplicates, sometimes in a slightly different form or presentation. Some wirings are given as reverse wirings without this being explicitly explained and some of the wirings are given with clip differences and twists. The data should therefore be used with care keeping in mind that the wirings are in many cases based on cryptanalytical recoveries and that they do not always correspond to the original wirings. Furthermore, it is expected that the information given will contain some errors.

By means of the following report, it is intended to bring together under one cover the available Enigma cipher machine wirings used prior to 1946. As one of the principal targets of the combined Anglo-American cryptanalytic effort during World War II, the German Enigma machine was the basis for a considerable number of reports. These have been searched for pertinent material. The record of Enigma wirings is complex and varied due to the use of this machine by many countries in one of its basic forms, or with alterations and innovations. Included in this paper are rotor wirings given by the British, the U.S. Navy, Coast Guard, and Army. Some of these wirings are clearly and explicitly presented; others are briefly noted; many have been taken from work sheets, and bits of scattered, unassociated papers wholly intelligible only to their originators; some exist without accompaniment of explanatory data. Wirings and the machines to which they pertain will be discussed briefly under separate headings insofar as data is available.
Suggestions, critical comments, and additional sources of Enigma information are welcomed from readers for use in subsequent editions of this paper.

Due to the size of this document, which has 208 printed pages — blank pages have not been copied, the document will be offered in two forms: As one full document and as separate chapters. Chapter IV consists of five parts. Because the file size of the full document is 52 MB it is advisable for readers on mobile devices to use the version with chapters.

Catalog of Enigma Cipher Machine Wirings, Complete:
Catalog of Enigma Cipher Machine Wirings

Catalog of Enigma Cipher Machine Wirings, In Chapters:

Cryptanalytical Documents

For the students who want to fully understand how to analyse and break the Enigma a close study of Alan Turing’s Treatise on Enigma is highly recommended. The papers written by C.H.O’D. Alexander, The Alexander Papers, also contain many important techniques on how to cryptanalyse the Enigma.

The Polish break into the Enigma is described by Marian Rejewski in his paper on  Breaking the Enigma Cipher  The paper has been transcribed by Enrico Grigolon and is reproduced here with the permission of The Institute of Mathematics ©, The Polish Academy of Sciences.

Professor Jiří Tůma has prepared a presentation on the use of permutation group for breaking the Enigma:
Permutation Groups and the Solution of German Enigma Cipher

A question that is frequently posed is how to recover the wheel (rotor) wiring of a machine like the Enigma. Alan Turing explains in his Treatise on Enigma the ‘Rodding’ and ‘Buttoning-up’ procedures that can be used for wiring recovery. Frank Carter has written two very good articles that explain the principles behind ‘Rodding’ and ‘Buttoning-up’, two techniques developed by Dillwyn Knox. They are available here together with other cryptanalytical articles written by Frank Carter. Previously these article where available from the The Bletchley Park Web pages, but now all cryptanalytical information seems to have vanished. I am therefore hosting local copies here:

To further increase the knowledge about this topic I am releasing two documents that explain in more detail how to recover the wheel wiring. The first document is written by Dr. Rudolf Kochendörffer (21.11.1911 – 23.8.1980), a German mathematician and Professor at the University of Dortmund who specialized in algebra and group theory. The paper is not dated and as it is in English it probably has been translated by the British or Americans after the Second World War. The text deals with the commercial Enigma, Enigma K. My first guess was that it was written in the early 1930s, but since then I have learned that in 1944 he was an Uffz. (Unteroffizier – non-commissioned officer) working in the Mathematische Referat (mathematical department) of OKH / In 7/IV the German Army High Command’s cryptographic organization. The second document is written by Lt. Robert E. Greenwood, Lt. Andrew M. Gleason, Lt. Alfred H. Clifford and Lt. Cdr. E. H. Hanson, all officers in the US Navy and attached to its signal intelligence department OP-20-G. The wiring recovery method that is described is a lot more powerful than the ‘Rodding’ and ‘Buttoning-up’ methods described by Alan Turing, mainly because it allows recovery of the wiring even when the Stecker is unknown.

The Enigma Series

This series consists of original memoranda written by members of the cryptanalytical research section of the U.S. Naval Communications Intelligence Staff, OP-20-G, and by others working with this research group, OP-20-GE – previously OP-20-GM, whose section head was Lt. Commander Howard H. Campaigne.

I should like to thank Ralph Erskine and Philip Marks for their help with these reports. Ralph Erskine did the first archive research in the Crane Collection located in Record Group 38 at NARA, College Park and he made the first set of copies. Philip Marks then revisited the collection on several occasions to make copies of the reports that I was missing.

The Series Foreword gives the ground rules for understanding these publications.

The Enigma Series Index.

Decoding Projects

Patents and Manuals

Arthur O. Bauer has published a large number of German, Dutch, French, English and US Enigma patents. He has also published a copy of the German instruction manual for the Naval Enigma M4. The copies are available here:

General Information

Enigma Messages and Keys

Enigma Papers and Thesis

Enigma Simulators

Replica Machines

Enigma Links

Here are a few links to other sources of Enigma information:



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The material described on these pages is created, collected, edited and published
by Frode Weierud, © February 2016

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