A few days ago I blogged about an unknown cipher disk from Pleidelsheim, Germany. Now a reader has sent me pictures of a very similar device. It stems from Norway.

My blog entry from last Sunday was about a cipher disk from the collection of my Dutch friends Paul Reuvers and Marc Simons. The two describe this device on their CryptoMuseum page. A similar disk is displayed on a photo available on Wikimedia Commons. Both disks were produced by a company named Linge in Pleidelsheim, Germany. The production time is unknown. My guess is that it was fabricated between 1920 and 1960.


The Gundersen & Löken disk

Earlier this week I received a mail from a reader, who wants to stay anonymous. He sent me a few pictures of a cipher disk he owns. It looks very similar to the one from Linge:


However, this disk uses a Norwegian alphabet. On the rear-side it can be seen that the disk was produced in Norway:


The inscription says “Gundersen & Löken Kristiania”. Here’s the writing in more detail:


“Kristiania” used to be the name of Norwegian capital Oslo between 1877 and 1924. If my age estimate (between 1920 and 1960) is correct, this means that this disk was produced in the early 1920s. This was a time when many new cipher machines and devices were developped – e.g., the Enigma, the Kryha machine, and the Damm machines, just to name a few. Many of these designs were either insecure or impractical or both. Most of them never made it to serial production. It is well possible that the Linge disk was one of these new but cryptographically weak developments which had no success on the market.

The company Gundersen & Löken apparently still exists today. I will write them a mail and ask if they have any information about this device.


A German-Norwegian co-production?

Here are the three disks on one picture (the CryptoMuseum Linge disk, the Wikimedia Linge disk, and the Gundersen & Löken disk).


One important question is, why the same model was produced in both Germany and Norway. Was the one disk a license production of the other? For whom were these disks made? When exactly were they fabricated?

If a reader knows more, please let me know.

Further reading: German cipher machines in World War 2: A complete (?) list

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Kommentare (5)

  1. #1 Thomas
    20. Juli 2017

    I wonder why “Löken” has no Norwegian ‘o’ like in this example: https://digitaltmuseum.no/011025242966/strommaler

  2. #3 Rich SantaColoma
    21. Juli 2017

    You are correct these are not at all secure, but I would imagine they were secure enough for the time they were produced, for the purposes they may have been intended for: Postcards and telegrams.

    For those, they would offer reasonable security, because both communications would not usually been seen but for a few moments by the necessary handlers of them. Any nosy person would have to take the time to copy the text down, and solve them later. Probably a hard task that would not go unnoticed in a post office or telegram office.

    And then, as postcards and telegrams fell out of favor, and technology moved on, such cipher devices no longer had a market. Maybe?

  3. #4 Thomas
    21. Juli 2017

    According to roel’s source the Norwegian disk was produced 1889 – 1916. 1917 is the terminus ante quem because the Norwegian A is missing, which has been introduced in 1917. Since according to the G & L website https://gl-instrumenter.no/ the enterprise was established in 1899 (not 1889), the disk must have been produced 1899 – 1916.

  4. #5 Frode Weierud
    Oslo, Norway
    27. Juli 2017

    The Norwegian disk is officially called Kryptografen, Anno 1900, Nr. 5. It was in use by the Norwegian army from 25 October 1900 until 1 January 1925 when it was taken out of service. Before that time the army used another another cipher disk patented by the Norwegian painter Georg Fredrik Strømdal on 21 February 1893, Norwegian patent no. 3121. This cipher disk was in use by the army from 1893 to 1900. However, Strømdal’s cipher disk was a better construction than Kryptografen Anno 1900, because the letters on one of the alphabet rings were removable and allowed one to use a changeable and complete scrambled alphabet. Strømdal also patented his cipher disk in Germany, France, Austria, Denmark, Sweden and USA. The US patent number is 546035 and the German patent number is 72239.
    For the really interested here are the instructions of use for Kryptografen Anno 1900: https://drive.google.com/file/d/0B4kbFLtvhKSsM2dSZXJLZlM5YzA/view?usp=sharing