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Two dimensional voice scrambler
TELSEC-02 was a frequency and time domain (F/T)
voice scrambler
for use on narrowband FM radio circuits, developed in 1987 by
Teltron
in München (Germany) especially for use with
car phones on the analogue German C-Netz network [1]. It was also used
by the Dutch police, during the high profile kidnapping case of
Ahold manager Gerrit Jan Heijn, in September 1987 [2].
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The unit measures 182 x 125 x 38 mm and weights 710 grams. It has a
metal rail at either side, allowing it to be mounted in a cradle
when fitting it under the dashboard of a car. At the rear is a DB25
socket for connection to the radio telephone set. The unit must be
programmed with an encryption key that is held on a key card.
The device was intended for use with analogue mobile (car) phones, such
as the German 450 MHz C-Netz [1], for which the existing 20 kHz bandwidth
was sufficient. It offered a reasonable protection against the occasional
interceptor.
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On 9 September 1987, top manager Gerrit Jan Heijn was kidnapped in front of
his own house in Bloemendaal (Netherlands) by Ferdi Elsas [2].
His grandfather was Albert Heijn, who founded the family business, and his
brother, also named Albert Heijn, was the founder of the Ahold empire.
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An unemployed engineer, Elsas held a grudge against his former business
partners, and was planning to have them killed, for which he needed a lot of
money. He wanted to gain this money by kidnapping Heijn for randsom 1 [3].
Although he murdered Heijn on the evening of the kidnapping, he successfully
pretended that Heijn was still alive for a long time, for which he had saved
Heijn's glasses and his cut-off little finger. During the following months,
Elsas asked for a randsom and communicated with Heijn's family via
coded messages in the newspaper.
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As the police did not have a proper secure communication system with national
coverage at the time, it was decided to use car phones on the
Dutch ATF-2 network.
ATF-2 provided national coverage with automatic hand-over, but was
not protected against eavesdropping in any way.
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Anyone with a (computer) scanner
that covered the 450 MHz band was able to
eavesdrop on any conversation that took place on the network, and it was known
to the police that scanner listeners, hobbyist and probably the
press as well, were continuously scanning the waves for material.
Luckily, Teltron had just completed the design of the TELSEC 02 and had
carried out the first tests on the German C-Netz [1],
which was similar to the Dutch ATF-2.
Two sets were flown in with the highest priority and were
connected to the modified handset
of a Nokia RD-59 car phone. 2
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The images above show one of the actual sets that was used in the months
after the kidnapping and the handover of the randsom.
Although voice scramblers are inherently insecure, the TELSEC 02 was considered
sufficiently secure for this purpose as it kept out (un)intentional listeners
like the press.
In fact, during the 1988 Carnahan Conference on Electronic Crime
Countermeasures of the IEEE in Montral (Canada), the device was considered
inexpensive and extremely effective [4].
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Heijn was in no way related to Elsas or his former business partners.
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In the Netherlands known as CARVOX 2453.
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The diagram below shows the complete setup of the Telsec 02, as it was used
in the Gerrit Jan Heijn kidnapping case.
At the top left is the actual encryption unit
(scrambler), with the keycard on top. This card, which has a magnetic strip,
should be inserted into the slot at the front panel.
All connections (power, audio input and audio output) are available on a
25-pin DB25 socket
that is wired to the connector of the handset, which has
been modified for this purpose. The black connector is
fitted to the handset socket of the phone.
The radio telephone itself is not modified.
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The Telsec 02 is housed in a strong aluminium case with enforced profiles at
the sides. It consists of a frame –
that holds the PCBs, the front and the
rear panel – and two metal U-shaped
shells, one at the top and one at the bottom. The shells are held in place
by four recessed screws each.
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A standard Omron cardreader
is fitted to the main board. It contains a
head that can read the information on the magnetic strip of the key card
whilst it is being inserted.
Judging from the
date code on the ASIC
– which was produced in week 4 of
1987 – the Telsec 02 was developed during the first half of 1987.
This means that it was just ready before the Gerrit Jan Heijn case.
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© Crypto Museum. Created: Wednesday 12 June 2019. Last changed: Tuesday, 07 June 2022 - 19:10 CET.
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![Ferdi Elsas - kidnapper and murderer of Gerrit Jan Heijn - during the reconstruction of the case shortly after his arrest in April 1988. Copyright unknown [5].](../../../covert/cases/heijn/img/FerdiE_Bloemendaal.jpg)
![Ferdi Elsas during the reconstruction at the murder scene [6]](../../../covert/cases/heijn/img/FerdiE_Renkum_thumb.jpg "image # heijn/img")
![Ferdi Elsas during the reconstruction at Heijn's house [6]](../../../covert/cases/heijn/img/FerdiE_Bloemendaal_thumb.jpg "image # heijn/img")
![Ferdi Elsas and the Heijn family communicated through coded ads in the newspaper [6]](../../../covert/cases/heijn/img/FerdiE_Ad_thumb.jpg "image # heijn/img")
![Ferdi Elsas during the reconstruction at the murder scene [6]](../../../covert/cases/heijn/img/FerdiE_Renkum.jpg)
![Ferdi Elsas and the Heijn family communicated through coded ads in the newspaper [6]](../../../covert/cases/heijn/img/FerdiE_Ad.jpg)
