INTELLIGENCE agencies won鈥檛 have any trouble working out how to snoop
unnoticed on satellite phone calls. The information has just been published in
patents filed by Motorola in the US and Europe.
Motorola developed the first cellphone system more than 20 years ago, along
with the exchanges that connect standard cellphones to the public telephone
network. It then went on to develop satellite telephone technology for the
Iridium and Teledesic services.
To stress the value of the ideas in its patents, Motorola first explains how
the security services eavesdrop on conventional cellphone calls: snoopers set up
a monitoring station at the exchange where cellphone calls are connected to the
fixed public phone network, and simply tap into the link.
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Motorola then points out that this would often not be possible with satellite
phone calls. Like cellphone systems, they route some calls through the public
phone network via gateways on the ground, and these are easy to intercept. But
other calls are routed directly to the receiving subscriber via a direct space
link (see Diagram),
making interception much more difficult. If space calls are
diverted through a ground station for the benefit of eavesdroppers, the signal
is delayed and degraded. This alerts the caller, and makes unobtrusive
interception 鈥渄ifficult or impossible鈥�, Motorola says.
The solution鈥攚hich Motorola is patenting, and therefore has to
reveal鈥攖akes advantage of the way satellite systems use ground control
centres to authenticate space calls. When a subscriber dials a number, their
satellite phone 鈥渉andshakes鈥� with the nearest satellite overhead. The satellite
sends a data signal down to the nearest ground station so that it can check the
subscriber鈥檚 details and authorise the call connection. If the call is routed
directly between satellites, the speech signal doesn鈥檛 travel down to Earth.
But, Motorola reveals, it can be made to.
To allow eavesdropping, the ground station sends a control signal telling the
satellites to send it a replica of the conversation. This signal can then be
intercepted by anyone with access to the station. Meanwhile, the space link
carries on working normally, so callers cannot tell they are being bugged.
The British human rights pressure group Liberty is already calling for
amendments to the Regulation of Investigatory Powers Bill now going through
Parliament. If passed, Liberty says the bill will let the police and security
services intercept calls if they pose a risk to national security or economic
well-being, or involve serious crime.
These criteria are 鈥渆xtremely vague and subjective鈥�, warns Liberty. 鈥淭hey
could include industrial action and organised protest.鈥� Liberty鈥檚 director, John
Wadham, told New 杏吧原创: 鈥淲e are very concerned now to learn that a
commercial organisation is making it possible to eavesdrop on satellite
telephone calls. We want to see it made a criminal offence for any organisation
to interfere with any communications without judicial warrant.鈥�