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The device was developed as a move away from earlier
cipher machines that were either based on
rotors, such as the Enigma and
Hagelin machines, or on
one-time tape (OTT), such as the
Philips Ecolex II and
Hagelin ULES 64 mixers.
The image on the right shows a complete Myosotis installation
as it was presented in 2022 by Jean-Lous Desvignes in
Bulletin de l'ARCSI [3].
The device consists of two 19" rackmountable enclosures:
a 3U unit that contains the interface to the line and the teleprinter,
and a 7U unit that contains the actual cipher unit.
At the bottom left of the cipher unit are two pluggable blocks:
a 10 unit one, and one that is 11 units wide.
The cipher unit is covered by a hinged lid at the front.
Once the key is setup, this lid should be closed.
For further information about the device, please refer to the
article Histoire de la machine Myosotis,
that was published in 2004 by some of the original developers:
Xavier Ameil, Jean-Pierre Vasseur and Gilles Ruggiu
(ARCSI members) [1].
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The exact operation of the device is still unknown, but according to
a description by the former developers, it is based on pseudo-randomly
generated alphabets, although it is not clear what is meant by this [1].
In any case, it is not based on linear feedback shift registers (LSFR).
Approx. 1500 units were made between 1966 and 1974
for the French Armed Forces and the Foreign Office.
Despite foreign interest, MYOSOTIS was never sold to other countries.
This was caused by lack of export licence policy, and also lack of funding for
developing a non-national encryption device. Instead it was dediced to
classify the machine as well as its name 'MYSOTIS'.
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In 1958, NATO announced that it was looking for a
tapeless rotorless on-line cipher machine (TROL)
to replace the ageing rotor and
one-time tape machines.
NATO countries were invited to submit designs for a TROL-competition
that would start in July 1962, with a deadline in February 1963.
Competing countries were USA (KW-7),
UK (ALVIS), Germany
(Elcrotel) and the Netherlands
(Ecolex V).
France was relatively late to enter the race just before the deadline,
with MYOSOTIS and another French machine: ULYSSE II.
The latter was backward compatible with NATO's KL-7.
As France was relatively late to submit a TROL-design,
it had to be developed in a rush [1]. Despite good intentions,
the competition was lost to the
British ALVIS (BID/610) (and at a later stage also to
the American KW-7), in what was thought to be a political
decision.
Nevertheless, it won from its national competitors VIOLET and ULYSSE II,
and was choosen as the common machine for the French Armed Forces
(Navy, Air Force and Army) and the French Ministry of Foreign Affairs.
MYOSOTIS was taken into production in 1966, and by 1974, 1500 units
had been made.
Although Silicon transistors had become available by the time MYOSOTIS
was taken into mass production (1966), it was too late to change the design,
as a result of which MYOSOTIS was build with Germanium transistors.
Approx. 20 years later, at the request of the Ministry of Foreign Affairs,
the machine was redesigned with silicon-based large-scale integrated
circuits (VLSI).
➤ More about the TROL competition
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Device Teleprinter encryption/decription device Purpose Secure on-line/off-line teleprinter traffic Category Tapeless Rotorless On-Line (TROL) Name Myosotis 1 Manufacturer CSF 2 (with SEFT) Production CSF (parts by SAGEM) Development 1961-1963 Production 1966-1974 Country France Users French Army, Navy, Air Force, Foreign Ministry Parts 2 (Control block, Cipher block) Algorithm Proprietary, non-linear Period Minimum: ~ 3.2 × 109, average: ~ 3 × 1012 Clock 1 MHz Transistors 1000 Diodes 4000 Dimensions see below Weight see below Quantity 1500 Price FFR 250,000 (1970) 3
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Dimensions 390 × 200 × 420 mm (HWD) 4 Weight 19 kg
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Dimensions 340 × 455 × 370 mm (HWD) 4 Weight 48 kg
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Myosotis is the French name of a Forget-Me-Not (flower).
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In 1968, CSF
merged with Thomson to become Thomson-CSF.
Today it is known as Thales.
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Including wired modem.
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These dimensions, taken from [1], are believed to be incorrect.
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- Histoire de la machine Myosotis
Xavier Ameil, Jean-Pierre Vasseur and Gilles Ruggiu (ARCSI) (in French language).
Proceedings of the 7th Conference on the History of Computing and Transmission.
Aconit Grenoble, 2004. pp. 95—125.
This article contains some factual mistakes and omissions. It gives an incorrect
description of the KL-7 rotor machine and claims that the
other French TROL design (ULYSSE II) was never submitted to NATO, which
is contradicted by NATO documents [4]. Furthermore it does not list the
Ecolex V (submitted by
the Netherlands) as a competitor, whilst the entries
from USA, UK and Germany are acknowledged.
- AICPRAT, La belle histoire de Thales - Épisode 3
19 March 2023.
- Jean-Louis Desvignes, De la C-36 à la carte CP8
Bulletin de l'ARCSI, volume 48, 2022. pp. 43-51.
- Ernst Ferber, Selection of Standard NATO on-line Teleprinter Cryptographic Equipment
Preliminary choice of preferred TROL equipment by the Standing Group of the Military Committee.
NATO, 1 February 1965.
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© Crypto Museum. Created: Saturday 04 October 2025. Last changed: Sunday, 05 October 2025 - 12:43 CET.
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![Complete MYOSOTIS cipher system. Photograph provided by Jean-Louis Desvignes (ARCSI) [3].](img/myosotis_large.jpg)