[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
New NSA patent explicity mentions machine transcription
In today's Indy:
By Suelette Dreyfus
15 November 1999
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
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
"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
Julian Assange, a cryptographer who moderates the online Australian
discussion forum AUCRYPTO, found the new patent while investigating
"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
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
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,"
"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.