As far as we know, there are no surviving Ecolex I machines and the
photographs presented on this page are probably the only ones left.
The image on the right shows a complete setup, consisting of a
Siemens T-37 teleprinter at the left, a double Siemens paper-tape reader
at the center and the Ecolex-I system itself at the right.
The large power supply unit,
was unually hidden under the table.
The Ecolex is based on the well-known principle of the
which is implemented here with no less than 69 valves.
Initially, the Ecolex I (or 'Ecolex' as it was called at the time) was
used by the Dutch Department of Defense (DoD) for military traffic,
and by the Dutch Foreign Office for diplomatic traffic at the highest
level of classification. It was later also offered to NATO and to other
NATO countries, but lost the race to the
Norwegian ETCRRM machine.
In total, only 25 Ecolex I machines were ever built .
The machine was succeeded in 1958 by the fully transistorized
One-time tape machines like the Ecolex I are in theory unbreakable
if, and only if, the keystream tape is truely random.
In practice however, the tapes were often generated by other (mainly
mechanical) pseudo-random number generators (PRNG) and were therefore
less secure. For this reason, the Dutch PTT developed its own
truely random noise generator: the EROLET.
In the years following WWII, the countries of the Western Union (WU)
had a growing need for secure military and diplomatic communications
equipment. After the WU had been dissolved into the newly established
the need for secure communication increased drastically. Initially,
only the British 5-UCO,
a left-over from WWII, was available for this,
but the British were unable to supply it in sufficient quantities to
fulfill the needs. Apart from that, the 5-UCO was a rack-based solution
that was way too large to be of any practical use in the field.
In 1953, the Norwegian company STK
tried to fill the gap by developing the ETCRRM,
a valve-based OTT machine that was much smaller than the
5-UCO and easily fitted a table top. After several improvements, SECAN
approved the ETCRRM for use by NATO on 19 April 1954 .
Around the same time (1952/53) the Dutch Post Office (PTT) started its own
development of a mixer machine (OTT), probably at the request of the
Dutch Government. The machine was ready in mid-1953 and existed in
two variants: Ecolex Mark I and Mark II 1 . A description was sent to
NATO on 4 August 1953 , but it wasn't until 12 August of the next
year that the two machines were approved for COSMIC messages
and NATO messages higher than CONFIDENTIAL .
As the Dutch PTT did not have its own production facilities,
the Ecolex I was built at Philips Usfa
in Eindhoven (Netherlands),
which was already a strong contract partner of the Dutch Department
of Defense (DoD) since 1949. The machine was in production until 1958
and in total only 25 units were built before it was succeeded
by the much smaller and fully transistorised
The price for a single Ecolex Mark I unit in 1955 was US$ 6000
and for an Ecolex Mark II unit 'just' US$ 3000 1 , with a lead time of 12 and 11 months
respectively. The ETCRRM on the other hand was produced at a rate
of 200 units per month and was available immediately at a unit price of
just US$ 1200 . Needless to say that the ETCRRM won this race.
Mark I and Mark II should not be confused with Ecolex I and Ecolex II
which are two entirely different machines. Mark I and Mark II are two
variants of the Ecolex I which was simply called 'Ecolex' back then.
The differences between the two variants are currently unknown.
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© Crypto Museum. Last changed: Friday, 28 August 2015 - 15:49 CET.