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Transvertex was a Swedish manufacturer of cipher machines, founded on 9 April 1951 by Vigo Waldemar Lindstein (a former employee of Boris Hagelin), Per-Erik Ahlman, Bengt Florin and W. Johnsson. The company was initially known as Invertex, but was later renamed Transvertex.

Transvertex logo, copyright Crypto Museum

Over the years, Transvertex manufactured a range of encryption devices, mainly for the Swedish Army, but also for other countries. In 1969, the company was taken over by LM Ericsson, after which the name Transvertex gradually disappeared. Little is publicly known about the company.

Transvertex cipher machines on this website
Vigo Waldemar Lindstein
During WWII, Transvertex co-founder Vigo Waldemar Lindstein worked for LM Ericsson Kassa Register (Cash Registers). As he was a gifted engineer, he was asked to develop a machine for automatic decryption of the Siemens T-52 A/B Geheimschreiber — a high-end cipher machine that was used by the German Army [3]. The initial version of the T-52 had been broken by the Swedish cryptanalist Arne Beurling in May 1940, and Beurling wanted Lindstein to build a machine that simulated the Geheimschreiber. In August 1940 the machine (called 'app') was ready and by the end of 1940, after a series of improvements, 33 such machines were in operation.

After his work on the Geheimschreiber, Lindstein became Chief Engineer at AB Cryptoteknik (Hagelin) in Stockhold (Sweden), which is where he gained his knowledge of pin-wheel based cipher machines. Back in 1935, Hagelin's C-35 had been the first fully mechanical pin-wheel machine. Hagelin's company was well-known to Ericsson, as it supplied its first cipher machine – the B-21 – to Ericsson for sending secure messages over insecure telephone lines in South-America [4]. Some of these machines were even built by Ericsson under license from Hagelin.

In the early 1950s, the Swedish government passed a law that put restrictions on the export of cipher machines, as a result of which Boris Hagelin made plans to move his business to neutral Switzerland. Lindstein left the company and teamed up with Per-Erik Ahlman, Bengt Florin and W. Johnsson to form a new company that would fill the gap that was to be left by Hagelin. Florin was a former colleague of Lindstein, who had worked with him at Ericsson in Hägerstein (Sweden).

The first plans for a new company date back to 12 July 1950. The initial goal was to manufacture the so-called HC cipher machine, developed by Vigo Lindstein in the late 1940s. As Lindstein was a former employee of Boris Hagelin, he had to use a different operating principle in order to avoid patent infringement. The HC-machine would later evolve into the well-known HC-9 [1].

Not much happened after the initial meeting, and it wasn't until the founders met again on 15 January 1951, that the plans were resumed. The company was founded on 9 April 1951 with Lindstein as CEO, and was initially called Invertex, hence the logo of the interwoven letters I and X. The first machine manufactured by Invertex was the SA-1 Teletype Ciphering Machine [1].

As the name Invertex had already been registred by another company, it was eventually changed to AB Transvertex, but the original logo with the interwoven I and X was kept.

Over the years, Transvertex manufactured a range of mechanical and electronic cipher machines, mainly for the Swedish Army. Some of their machines found their way into other countries, such as Brasil and Argentina. In the early years, most of the design work was done by Vigo Waldemar Lindstein and Per-Erik Ahlman. in the early 1960s, their work was taken over by Bengt Florin and Kalevi Loimaranta. Florin was Lindstein's former Ericsson colleague and Transvertex co-founder.

Loimaranta was a Finnish intelligence engineer who had fled Finland in 1944 in fear of a Soviet invasion, as part of Operation Stella Polaris [5]. He worked at the Swedish Intelligence Service FRA from 1944 to 1957, and from 1957 onwards at Atomenergi, a company for the development of nuclear energy in Sweden. He returned to Finland in 1964 [6].

In December 1969, Transvertex was bought by the Swedish telephone equipment manufacturer Telefonaktiebolaget L.M. Ericsson, currently known as Ericsson. Vigo Waldemar Lindstein had been the CEO of Transvertex from its foundation in 1951 to the takeover by Ericsson in 1969 [1].

In the early 1950s, Transvertex developed the fully mechanical HC-9 cipher machine for the Swedish Army. It physically resembles a Hagelin cipher machine, such as the C-36 and M-209, but uses a punched card instead of pin-wheels.

 More information


Over the years, a number of patents have been filed on behalf of Transvertex, in a variety of countries. In the beginning, most designs were made by Vigo Lindstein and Per-Erik Ahlman. In later years patents were often attributed to Florin Bengt and Loimaranta Kalevi.

We've listed the patents that we have found on a separate page. You can help us by finding more patents.

 More information


  • SA-1
    Teletype Ciphering Machine
  • HC-9
    Portable mechanical cipher machine
  • HC-110
    Compact offline electronic ciphering device
  • TC-213
    Online/offline cipher machine for teleprinters (telex)
  • SV-250
    Speech encryption device
  • ST-320
    Military voice encryption device for radio
  • CD-410
    Multiplexed digital data encryptor with PCM and CVSD
  • TD-265
    Full-duplex line encryptor with HDLC
  1. Torbjörn Andersson, Transvertex, Swedish Manufacturer of Ciphering Machines
    Information about Transvertex reproduced here with permission from the author.
    Website no longer available (2022).

  2. US Patent 3557307, Ciphering Machine
    19 January 1971. This patent gives details about Florin and Loimaranta.

  3. CG McKay and Bengt Beckman, Swedish signal intelligence 1900-1945
    2003. ISBN 9780714652115 (hard cover). ISBN 0-7146-5221-3 (cloth cover).

  4. Crypto Museum, Hagelin B-21 cipher machine
    Example of a B-21 that was actually used by LM Ericsson.

  5. Wikipedia, Operation Stella Polaris
    Visited 3 April 2022.

  6. Anders Wik, Personal correspondence
    April 2022.
Further information
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Crypto Museum. Created: Tuesday 04 August 2009. Last changed: Wednesday, 08 May 2024 - 13:50 CET.
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