http://www.independent.co.uk/news/Digital/Features/spies151199.shtml
This is just between us (and the spies)
The US National Security Agency has patented a new technology for
monitoring millions of telephone calls, so watch out, it's now even easier
for the spooks to eavesdrop on your conversations
By Suelette Dreyfus
15 November 1999, The Independent (UK)
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.
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.
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.
"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.
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.
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.
"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.
"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."
The NSA declined to comment on the patent. As a general policy, the agency
never comments on its intelligence activities.
Yaman Akdeniz, director of Cyber-Rights & Cyber-Liberties UK, warned that
with the new patent and 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."
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.
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.
Julian Assange, a cryptographer who moderates the online Australian
discussion forum AUCRYPTO, found the new patent while investigating NSA
capabilities.
"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.
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.
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.
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".
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.
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.
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.
"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.
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.
"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.
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.