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- The US National Security
Agency has designed
and patented
a new technology that could aid it in spying
on international telephone
calls. The NSA patent, granted on 10 August,
is for a system of automatic
topic spotting and labelling of data. The
patent officially confirms for
the first time that the NSA has been
working on ways of automatically analysing
human speech.
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- The NSA's invention
is intended automatically to sift
through human speech transcripts in
any language. The patent document specifically
mentions
"machine-transcribed speech" as a potential source.
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- Bruce Schneier,
author of Applied Cryptography, a textbook
on the science of keeping
information secret, believes the NSA currently
has the ability to use
computers to transcribe voice conversations.
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- "One of the holy grails of
the NSA is the ability
automatically to search through voice traffic.
They would have expended
considerable effort on this capability, and
this indicates it has been
fruitful," he said.
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- To date, it has been
widely believed that while the NSA
has the capability to conduct fully
automated, mass electronic eavesdropping
on e-mail, faxes and other
written communications, it cannot do so on telephone
calls.
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- While cautioning that
it was difficult to tell how well
the ideas in the patent worked in
practice, Schneier said the technology
could have far-reaching effects
on the privacy of international phone calls.
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- "If it works well, the
technology makes it possible
for the NSA to harvest millions of
telephone calls, looking for certain
types of conversations," he
said.
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- "It's easy to eavesdrop on any single phone call,
but
sifting through millions of phone calls looking for a particular
conversation
is difficult," Schneier explained. "In terms of
automatic surveillance,
text is easier to search than speech. This
patent brings the surveillance
of speech closer to that of
text."
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- The NSA declined to comment on the patent. As a general
policy,
the agency never comments on its intelligence activities.
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- Yaman Akdeniz,
director of Cyber-Rights & Cyber-Liberties
UK, warned that with
the new patentand a proposed AT&T and BT joint
venture, which will
allow US law enforcement agencies to tap the new communications
network: "We might have a picture in which all British communications
are monitored by the NSA."
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- The revelation of the NSA's patent is likely to cause
tensions with the European Parliament. Over the past two years, the
Parliament
has commissioned several reports which examined whether the
NSA has been
using its electronic ears for commercial espionage,
particularly in areas
where US corporations compete with European and
other companies.
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- The NSA relies on an international web of eavesdropping
stations around the world, commonly known as Echelon, to listen into
private
international communications. The network emerged from a secret
agreement
signed after the Second World War between five nations
including Australia,
New Zealand, Canada, Britain and the US. Two of
the NSA's most important
satellite listening stations are located in
Europe, at Menwith Hill in
Yorkshire and Bad Aibling in
Germany.
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- Julian Assange, a cryptographer who moderates the online
Australian discussion forum AUCRYPTO, found the new patent while
investigating
NSA capabilities.
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- "This patent should worry
people. Everyone's overseas
phone calls are or may soon be tapped,
transcribed and archived in the
bowels of an unaccountable foreign spy
agency," he said.
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- One of the major barriers to using computers
automatically
to sift through voice communications on a large scale has
been the inability
of machines to "think" like humans when
analysing the often imperfect
computer transcriptions of voice
conversations.
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- Commercial software that enables computers to transcribe
spoken
words into typed text is already on the market, but it usually requires
the machine to spend time learning how to understand an individual voice
in order to produce relatively error-free text. This makes such software
impractical for a spy agency which might want automatically to transcribe
and analyse telephone calls on a large scale.
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- It is also difficult for
computers to analyse voice conversations
because human speech often
covers topics that are never actually spoken
by name. According to the
NSA patent application, "much of the information
conveyed in
speech is never actually spoken and... utterances are frequently
less
coherent than written language".
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- US Patent number 5,937,422
reveals that the NSA has designed
technology to overcome these barriers
in two key ways. First, the patent
includes an optional pre-processing
step which cleans up text, much of
which the agency appears to expect
to draw from human conversations. The
NSA's "pre-processing"
will remove what it calls "stutter
phrases" associated with
speech based on text.
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- Second, the patent uses a method by which a computer
automatically assigns a label, or topic description, to raw data. If the
method works well, this system could be far more powerful than traditional
keyword searching used on many Internet search engines because it could
pull up documents based on their meaning, not just their keywords.
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- Dr Brian Gladman,
former MoD director of Strategic Electronic
Communications, said that
while he doubted the NSA had deployed the patented
system yet, the new
technology could become a "potent future threat"
to
privacy.
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- "If the technology does what it says - automatically
finding and extracting the meaning in messages with reasonable accuracy
- then it is way ahead of what is being done now," he said.
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- The best way for
people to protect their private communications
was to use encryption,
he said. Encryption software programs scramble data
to prevent
eavesdropping. "I'm afraid widespread interception is a
fact of
life and this is what makes encryption so important," he said.
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- "The problem in
the UK is that our government is
working with the US to prevent UK
citizens defending themselves using encryption,"
he said,
referring to the continuing use of export controls to hamper the
widespread availability of encryption products.
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- The NSA's current spy
technology may be more advanced
than methods described in the patent
because the application is more than
two years old. The US Patent
Office approved the patent on 10 August
this year, but the NSA
originally lodged the application on 15 April 1997.
The US Patent
office keeps all applications secret until it issues a patent.
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