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Enigma Patents
Last updated: 6 August 2012

The first patent for an Enigma machine, or at least something that would eventually evolve into an Enigma machine, was filed by the German inventor Arthur Scherbius in 1918 [1]. He worked in close collaboration with Hugo Alexander Koch [2] from The Netherlands, who had also patented a cipher machine. Koch's patents were later transferred to Scherbius' company.

It should be noted however, that the rotor machine machine was initially invented in 1915 in The Netherlands by two Naval officers, R.P.C. Sprengler (1875-1955) and Theo A van Hendel (1875-1939) [3]. Over the years, many aspects of the Enigma machine were patented in Germany, but also in other countries such as the USA, the UK, France, Switzerland and The Netherlands.

Below is a list of some Enigma-related patents, both in Germany and abroad. Although we have tried to be as complete as possible, it is entirely possible that we have missed some. If you known of any Enigma-related patent that is not listed here, please contact us. Click any of the patents below to download. Please note that the patents are sorted by date of issue and not by number. We should like to thank Frode Weierud, Arthur Bauer and many others for bringing some of these patents to our attention and for their help putting them in context.

The ownership of certain patents is sometimes a bit clouded. Arhur Scherbius, who is known as the first patent holder for an Enigma-like machine, initially traded under the name Gewerkschaft Securitas of Berlin (Germany). In 1927, Scherbius bought a similar patent (NL10700) from Hugo Alexander Koch in The Netherlands who had setup a special company in 1922 to hold the patent: Naamloze Vennootschap Ingenieursbureau Securitas in Amsterdam (Netherlands); two officially 'independant' companies with similar names.

In some countries, patents were filed by the German Securitas, (later Chiffriermaschinen AG 1) whilst the same patent was filed in other countries by the Dutch Securitas branch. This was probably done to avoid claims that, after WWI, Germany wasn't allowed to develop and produce certain high-tech equipment as part of the Versailles Treaty [4]. It is clear that the Dutch company acted as a cover for the German operation.

Scherbius would never see the great success of his Enigma machine as he died in a horse carriage accident in 1929. From then on, the company was effectively led by its major inventor Willy Korn, in whose name many later patents were registered. On the eve of WWII, the company name was changed to Heimsoeth und Rinke (also known during WWII by their manufacturer's code 'jla').

1) The name of Gewerkschaft Securitas was changed to Chiffriermaschinen AG in July 1923.
German Patents
  • DE416219 / 23 February 1918
    This is the first Enigma-related patent, filed by Arthur Scherbius, issued 23 February 1918. It was released on 8 July 1925.
    Click to view patent DE416219

  • DE416833 / 2 June 1918
    Supplement to patent DE416219 for the use of tubes instead of electric wires, to allow the machine to be driven by water, air or oil, instead of electricity.

  • DE387893 / 13 June 1920
    Cipher machine with multiple alphabets (e.g. upper case, lower case and numbers) using the letter 'j' to toggle between modes. Filed by Scherbius and Ritter in Berlin.

  • DE425147 / 26 Sep 1920
    Patent for a cipher machine in which each key-press causes an irregular movement of multiple cipher discs. The drawings clearly show an early concepts of an electrical cipher machine with drums for ciphering and deciphering.

  • DE378238 / 24 May 1921
    Cipher machine for the conversion of number into letters and vice versa, using a lamp panel for the output. Filed by Arthur Scherbius in Berlin.

  • DE409301 / 20 September 1921
    Patent for a ciphering machine with a reduced number of contacts (by introducing multiple shift keys), electrical coding wheels, and a printer with a rotating drum. Filed by Securitas Berlin (Germany). This patent is similar to US1584660.

  • DE383594 / 12 February 1922
    Patent for a ciphering machine with electrical coding wheels, filed by Securitas Amsterdam (Netherlands). This patent was also filed in other countries, e.g. United Kingdom (GB193035), USA (US1657411), and France (FR561910).
    Click to view patent DE383594

  • DE385682 / 10 May 1922
    Patent for the use of a multi-switches to select between substitution alphabets. Clearly related to the typewriter-style Enigma machines, such as the Enigma A. Filed by Securitas Amsterdam (Netherlands).

  • DE400795 / 18 Aug 1923
    Patent for the use of two separate printers, one for the plain text and one for the cipher text. Filed by Securitas Amsterdam (Netherlands).

  • DE411126 / 18 Aug 1923
    Patent for the use of index rings (letter rings) on the cipher wheels and on other parts of the turnover system, in order to set the message key. Filed by Securitas Amsterdam (Netherlands).

  • DE408949 / 9 September 1923
    Brake-system for rotating print wheels. Filed by Scherbius und Ritter in Wannsee (Germany).

  • DE407804 / 18 Jan 1924
    First patent for a cipher machine with light bulbs (Glühlampen}. Invented by Paul Bernstein. Filed by Chiffriermaschinen AG, Berlin.
    Click to view patent DE407804

  • DE454392 / 30 Jan 1924
    Patent for enhancing the irregular movement of the wheels during encipherment, in order to increase cipher security, by allowing a wheel to make multiple steps on a single key-press.

  • DE425566 / 28 Feb 1924
    Patent for allowing two different alphabets (letters and numbers/punctuation marks) to be enciphered, using just the 26 letters of the telegraph alphabet. This was done by replacing 'j' by 'i' and 'q' by 'k', and using the contacts for 'j' and 'q' to select between letters and numbers.

  • DE412582 / 25 March 1924
    System for blocking the various cipher components after each key-press. This should avoid a cipher wheel from making more than one step on a single key-press.

  • DE429122 / 26 March 1924
    Patent for a cipher machine in which cog-wheels with a varying number of teeth (prime numbers and numbers without a common factor) are used to create a pseudo-random generator with a very long period. This patent is clearly related to the design of the very first Enigma model: Enigma A, introduced in 1923.
    Click to view patent DE429122

  • DE460457 / 11 March 1926
    This patent introduces the Umkehrwalze (UKW) and the removable rotor-set (drum), invented by Willi Korn. It describes how the drum can be removed by using a lever to shift the UKW aside. This was done to allow the wheel order to be changed easily in the field. It also describes the top lid that can only be closed when the UKW lever is locked in position. The UKW is a basic element for all further Enigma machines.
    Click to view patent DE460457

  • DE452194 / 21 March 1926
    This patent further enhances the use of the Umkehrwalze (UKW), invented by Willi Korn. It describes mounting of a fixed UKW in multiple positions, setting the UKW to any of 26 positions, and allowing the UKW to move during encipherment. The latter was used in the Zählwerk Enigma.
    Click to view patent DE452194

  • DE554421 / 31 January 1928
    Patent for the addition of fixed user-rewirable wheels in between the moving cipher discs. This allowed each user to alter the wiring of the entire system and thus increase cipher security.
    Click to view patent DE554421

  • DE534947 / 9 November 1928
    First patent that shows the Zählwerk Enigma (also known as Enigma G). Full description of the cog-wheel mechanism and the fact that a crank can be used to correct mistakes and/or as part of the key. The patent also claims the use of a settable index ring (Ringstellung). The word Zählwerk refers to the cog-wheel mechanism as well as the counter.
    Click to view patent DE534947

  • DE579555 / 17 November 1928
    Further patent describing the Zählwerk Enigma. This is actually an extension to patent DE534947. It claims the use of multiple notches per wheel (e.g. prime numbers), interchangeable index rings and the fixing of the notches to the index ring. Both types of wheels (i.e. cog-wheels and notched wheels) are described in detail.
    Click to view patent DE579555

  • DE541702 / 30 January 1929
    Patent for the use of electromagnets in a typewriter or ciphering machine, in order to print a character on paper. Invented by Arthur Scherbius and Willi Korn.

  • DE524754 / 30 January 1929
    Patent that describes the construction of a cipher machine in which all keying elements are mounted on the same geometrical axis, making the setting of a message key much simpler as before. This includes both the electrical cipher discs and the gap-cog-wheels that drive the cipher discs. In previous systems a separate axle was used for each driving gap-cog-wheel. This patent clearly describes the Enigma H29.
    Click to view patent DE524754

  • DE550796 / 5 February 1929
    Patent for the addition of extra switching wheels, outside both fixed end-wheels, to allow easy selection between cipher, decipher and plain text, without the need for large - expensive - multi-pole switches.

  • DE536556 / 22 June 1929
    Patent for connecting a printing Enigma (Schreibende Enigma), such as the H29, to a lamp Enigma (Glühlampenmaschine) so that it can be used as a printing device. Invented by Willi Korn. The Enigma G111 is an example of a lamp-Enigma that was used this way.
    Click to view patent DE536556

  • DE607638 / 5 March 1930
    This patent clearly shows something that resembles the numbers-only Enigma Z30. A machine with 10 keys and 10 lamps. The patent also claims that the letter-caps over the lamps can be interchanged to provide an extra layer of encryption. To our knowledge, the latter wasn't actually used.
    Click to view patent DE607638

  • DE595075 / 4 November 1930
    Supplement to patent DE536556. Patent for a switching connector inside the Enigma, allowing the lamps to be switched off when a printer is connected. Invented by Willi Korn and Karl Röpke. Enigma G111 is an example of a lamp-Enigma that was issued with this connector.
    Click to view patent DE595075

Dutch Patents
  • NL10700 / 7 October 1919
    First Enigma-related patent registered in The Netherlands on 7 October 1919 by Hugo Alexander Koch. On 5 May 1922, the patent rights were transferred to Naamloze Vennootschap Securitas in Amsterdam, and on 28 January 1927 to Chiffriermaschinen Aktiegesellschaft in Germany (Scherbius).

  • NL12762 / 17 May 1922 (priority 23 May 1921)
    Patent for changing number-pairs into letter-pairs and vice versa, in order to avoid mistakes in sending (secret) telegrams. The patent was filed by NV Ingenieursbureau Securitas of Amsterdam on 17 May 1922, but claimed a priority of 23 May 1921 as a result of an earlier German registration. The patent is nearly identical to German Patent DE378238 which was filed by Arthur Scherbius a day later (24 May 1921). It was later transferred to Chiffriermaschinen AG in the same Act as the previous patent (see below).

  • Act of Transfer 886 / 5 May 1922
    On 5 May 1922, the legal rights of Patent Application 13046 (the later Patent NL10700) were transferred from Hugo Alexander Koch to NV Ingenieursbureau Securitas in Amsterdam (Netherlands) for the amount of NLG 500 (approx. EUR 225).

  • Act of Transfer (10700 and 12762) / 28 January 1927
    On 28 Janury 1927, the legal rights of both patents above (NL10700 and NL12762) were transferred by Hugo Alexander Koch, acting on behalf of NV Securitas (Amsterdam), to Chiffriermaschinen Aktiengesellschaft in Germany (Scherbius) for NLG 600 each.

UK Patents
  • GB163357 / 10 November 1919
    Improvements in and relating to Ciphering and Deciphering Machine. This patent is basically the British version of Koch's original Dutch Patent NL10700.

  • GB180653 / 1 May 1922 (priority 23 May 1923)
    Electric Ciphering Apparatus. This patent is basically a copy of Koch's second Dutch Patent NL12762.

  • GB213968 / 8 January 1923
    Ciphering Machine. Using multi-switches to select between subsitution alphabets. This patent is similar to German Patent DE385682 (19 May 1922) and was filed by NV Securitas in Amsterdam (Netherlands). It is clearly related to the printing Enigma machines.

  • GB193035 / 3 February 1923
    Patent for a chiphering machine, filed by NV Ingenieursburo Securitas of Amsterdam (Netherlands). This patent is identical to American patent US1657411, which was filed by Arthur Scherbius of Chiffriermaschinen AG.

  • GB233407 / 5 February 1924
    Electric Type Wheel Actions for Typewriting Machine. Filed on behalf of Scherbius and Ritter of Berlin (Germany).

  • GB231502 / 25 March 1925
    Patent for improving ciphering machines by using multiple ciphering discs and a complex irregular wheel turnover pattern by using special drive wheels. Filed by Chiffriermachinen AG of Berlin (Germany)

  • GB267472 / 17 January 1927
    Patent for the use of removable and interchangeable cipher discs and a reflector. This patent clearly shows an Enigma machine with three wheels and a fixed UKW. Filed by Chiffriermaschinen AG of Berlin (Germany).

  • GB343146 / 14 November 1929
    British version of patent DE534947 and DE579555 for the Zählwerk Enigma (Enigma G) with some additions. Filed on behalf of Chiffriermaschinen AG.

  • GB325020 ???
    This patent is mentioned on a shield that is mounted to the rear of the Enigma Model H29. However the patent is clearly not related to the Enigma in any way. It is possible that this was a so-called abandonned patent.

US Patents
  • US1533252 / 18 Sep 1920
    This is the US-version of the original Dutch Patent NL10700. It is filed by NV Securitas in Amsterdam (Netherlands) and lists Hugo Alexander Koch as the inventor.

  • US1556964 / 20 April 1922
    Patent for a simple ciphering machine allowing figures to be converted into letters and vice versa, printing directly to paper in a readable format. Filed by Arthur Scherbius on behalf of Securitas Berlin (Germany).

  • US1584660 / 7 December 1922
    Patent for a ciphering machine with a reduced number of contacts (by introducing multiple shift keys), electrical coding wheels, and a printer with a rotating drum. Filed by Arthur Scherbius on behalf of Securitas Amsterdam (Netherlands).

  • US1657411 / 6 February 1923
    First US patent that clearly resembles an Enigma machine, filed in the US by Arthur Scherbius on behalf of Chiffriermaschinen AG (Germany). Note that this patent is identical to DE383594, filed by Securitas Amsterdam (Netherlands) and British patent GB193035, also filed by Securitas.

  • US1520089 / 15 Feb 1924
    Patent for an Electric Typewriting Machine and improvements of such machines, filed on behalf of Arthur Scherbius. This patent is used in the Enigma Model H29.

  • US1777425 / 25 March 1925
    This is the US version of German Patent DE429122 (26 March 1924). It is filed on behalf of Chiffriermaschinen AG in Berlin (Germany) and lists Paul Bernstein as the inventor.

  • US1705641 / 19 March 1929
    Permuting Device for use in Coding Machines. This is actually identical to DE460457 of 11 March 1926, filed by Chiffriermaschinen AG in Berlin.

  • US1938028 / 5 November 1929
    This patent is the US version of German Patent DE534947 (9 November 1928). The patent is filed on behalf of Willi Korn, who is also listed as the inventor.

  • US1905593 / 12 November 1929
    This patent is the US version of German Patent DE579555 (17 November 1928). The patent is filed on behalf of Willi Korn, who is also listed as the inventor.

French Patents

Swiss Patents

  1. Wikipedia, Hugo Alexander Koch
    Dutch inventor (1870-1928).

  2. Wikipedia, Arthur Scherbius
    German electrical engineer and inventor (1878-1929).
    Official inventor of the Enigma machine.

  3. Karl de Leeuw, The Dutch Invention of the Rotor Machine, 1915-1923
    Cryptologia, January 2003, Volume XXVII, Number 1, pp. 73-94.

  4. Wikipedia, Treaty of Versailles
    28 June 1919 (at the end of WWI). Retrieved August 2012.

Further information

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