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Ecolex III
One-time tape cipher machine - this page is a stub

Ecolex-III was a One-Time Tape (OTT) cipher machine, developed around 1959 by Professor Oberman 1 at the Technical University of Delft (Netherlands). Prototypes of the machine were built by Philips Usfa NV in Eindhoven (Netherlands). It featured fast synchronisation, and was the anticipated successor to the Ecolex II, which had been developed by Oberman whilst working at the prestigious Dr. Neher Laboratory of the Dutch PTT. Ecolex III was never taken into production and the Ecolex II was eventually succeeded by the Ecolex IV, which was a Philips-development.

The machine follows the design strategy of the earlier Ecolex II and it based on an existing Siemens twin tape reader, identical to the one that was used for the Ecolex II. It is mounted on top of the actual mixer, which has become much larger due to the fact that is now includes a complete synchronizer as well. This is illustrated by the two prominently visible counters (DELAY and ADV) at the front panel of the bottom unit.

The machine was developed by Professor RMM Oberman and his assistent 2 Antonie Snijders, but was manufactured by Philips Usfa NV in Eindhoven, as Oberman's employer – the PTT – was neither interested in equipment production nor in the subject of cryptography in general.

Surviving correspondence between Oberman and Usfa director van Wijk, shows that between 1958 and 1959 they negotiated about reasonable royalties for Oberman and Snijders. The last contact was in spring 1960, but the settlement never came. It seems likely that this was a delaying tactic on the part of Philips Usfa.

There are two possible motives for the delay. Firstly, Usfa was already developing the Ecolex IV and needed time to circumvent Oberman's patents. Secondly, they might want to use Oberman's design after all – effectively a Plan B – should their own attempt fail [3]. There were also cultural differences between the parties: Oberman was a scientist with a fine eye for detail, whilst van Wijk was a typical manager who was not interested in details at all. In the end, the agreement was terminated, the Ecolex III was never taken into production and Usfa developed the Ecolex IV.

Apparently, the above disagreement between the parties did not harm their relationship; Oberman and Philips Usfa continued to cooperate on a number of other projects, such as the development of a One-Time Tape (OTT) adapter for the mechanical Hagelin cipher machines.

The image above shows a prototype of the Ecolex III (left) with a Siemens t.send.77f double tape reader on top. This is the same tape reader that was used with the Ecolex II and with the Siemens Schlüsselgerät D. At the right is a filter unit that is connected between the device and the line.

  1. Together with his colleague Antonie Snijders.
  2. Snijders was initially Oberman's assistent at the Dr. Neher Laboratory. He later also became a Professor at the Technical University of Delft (Netherlands).

  1. Maarten Oberman, Staatsgeheim, Beveiliging van Overheidsberichten
    State Secret, Government Message Security (Dutch).
    ISBN 978-9-4644-8870-8. 2022.
  1. Photographs from Philips Usfa
    Crypto Museum Archive. CM300624.

  2. Philips Usfa, Internal Memo L/5636/AvdP/JG
    23 August 1982, page 5. CM300428.

  3. Maarten Oberman, Staatsgeheim, Beveiliging van Overheidsberichten
    State Secret, Government Message Security (Dutch).
    ISBN 978-9-4644-8870-8. 2022.
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Crypto Museum. Created: Monday 25 May 2015. Last changed: Friday, 17 February 2023 - 12:17 CET.
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