From The Intercept, Jan. 19:
At the height of the Cold War, during the winter of 1980, FBI
agents recorded a phone call in which a man arranged a secret meeting
with the Soviet embassy in Washington, D.C. On the day of his
appointment, however, agents were unable to catch sight of the man
entering the embassy. At the time, they had no way to put a name to the
caller from just the sound of his voice, so the spy remained anonymous.
Over the next five years, he sold details about several secret U.S.
programs to the USSR.
It wasn’t until 1985 that the FBI, thanks to intelligence provided by
a Russian defector, was able to establish the caller as Ronald Pelton, a
former analyst at the National Security Agency. The next year, Pelton
was convicted of espionage.
Today, FBI and NSA agents would have identified Pelton within seconds of his first call to the Soviets. A classified NSA memo
from January 2006 describes NSA analysts using a “technology that
identifies people by the sound of their voices” to successfully match
old audio files of Pelton to one another. “Had such technologies been
available twenty years ago,” the memo stated, “early detection and
apprehension could have been possible, reducing the considerable damage
Pelton did to national security.”
These and other classified documents provided by former NSA
contractor Edward Snowden reveal that the NSA has developed technology
not just to record and transcribe private conversations but to
automatically identify the speakers.
Americans most regularly encounter this technology, known as speaker
recognition, or speaker identification, when they wake up Amazon’s Alexa
or call their bank. But a decade before voice commands like “Hello
Siri” and “OK Google” became common household phrases, the NSA was using
speaker recognition to monitor terrorists, politicians, drug lords,
spies, and even agency employees.
The technology works by analyzing the physical and behavioral
features that make each person’s voice distinctive, such as the pitch,
shape of the mouth, and length of the larynx. An algorithm then creates a
dynamic computer model of the individual’s vocal characteristics. This
is what’s popularly referred to as a “voiceprint.” The entire process —
capturing a few spoken words, turning those words into a voiceprint, and
comparing that representation to other “voiceprints” already stored in
the database — can happen almost instantaneously. Although the NSA is
known to rely on finger and face prints to identify targets,
voiceprints, according to a 2008 agency document, are “where NSA reigns
supreme.”
It’s not difficult to see why. By intercepting and recording millions
of overseas telephone conversations, video teleconferences, and
internet calls — in addition to capturing, with or without warrants, the
domestic conversations of Americans — the NSA has built an unrivaled
collection of distinct voices. Documents
from the Snowden archive reveal that analysts fed some of these
recordings to speaker recognition algorithms that could connect
individuals to their past utterances, even when they had used unknown
phone numbers, secret code words, or multiple languages.
As early as Operation Iraqi Freedom, analysts were using
speaker recognition to verify that audio which “appeared to be of
deposed leader Saddam Hussein was indeed his, contrary to prevalent
beliefs.” Memos further show that NSA analysts created voiceprints for
Osama bin Laden, whose voice was “unmistakable and remarkably consistent
across several transmissions;” for Ayman al-Zawahri, Al Qaeda’s current
leader; and for Abu Musab al-Zarqawi, then the group’s third in
command. They used Zarqawi’s voiceprint to identify him as the speaker
in audio files posted online.
The classified documents, dating from 2004 to 2012, show the NSA
refining increasingly sophisticated iterations of its speaker
recognition technology. They confirm the uses of speaker recognition in
counterterrorism operations and overseas drug busts. And they suggest
that the agency planned to deploy the technology not just to
retroactively identify spies like Pelton but to prevent whistleblowers
like Snowden.
Always Listening
Civil liberties experts are worried that these and other
expanding uses of speaker recognition imperil the right to privacy.
“This creates a new intelligence capability and a new capability for
abuse,” explained Timothy Edgar, a former White House adviser to the
Director of National Intelligence. “Our voice is traveling across all
sorts of communication channels where we’re not there. In an age of mass
surveillance, this kind of capability has profound implications for all
of our privacy.”
Edgar and other experts pointed to the relatively stable nature of
the human voice, which is far more difficult to change or disguise than a
name, address, password, phone number, or PIN. This makes it “far
easier” to track people, according to Jamie Williams, an attorney with
the Electronic Frontier Foundation. “As soon as you can identify
someone’s voice,” she said, “you can immediately find them whenever
they’re having a conversation, assuming you are recording or listening
to it.”
The voice is a unique and readily accessible biometric: Unlike DNA,
it can be collected passively and from a great distance, without a
subject’s knowledge or consent. Accuracy varies considerably depending
on how closely the conditions of the collected voice match those of
previous recordings. But in controlled settings — with low background
noise, a familiar acoustic environment, and good signal quality — the
technology can use a few spoken sentences to precisely match
individuals. And the more samples of a given voice that are fed into the
computer’s model, the stronger and more “mature” that model becomes.
In commercial settings, speaker recognition is most popularly
associated with screening fraud at call centers, talking to voice
assistants like Siri, and verifying passwords for personal banking. And
its uses are growing. According to Tractica, a market research firm,
revenue from the voice biometrics industry is poised to reach nearly $5
billion a year by 2024, with applications expanding to border
checkpoints, health care, credit card payments, and wearable devices.
A major concern of civil libertarians is the potential to chill
speech. Trevor Timm, executive director of the Freedom of the Press
Foundation, noted how the NSA’s speaker recognition technology could
hypothetically be used to track journalists, unmask sources, and
discourage anonymous tips. While people handling sensitive materials
know they should encrypt their phone calls, Timm pointed to the many
avenues — from televisions to headphones to internet-enabled devices —
through which voices might be surreptitiously recorded. “There are
microphones all around us all the time. We all carry around a microphone
24 hours a day, in the form of our cellphones,” Timm said. “And we know
that there are ways for the government to hack into phones and
computers to turn those devices on.”
“Despite the many [legislative] changes that have happened since the
Snowden revelations,” he continued, “the American people only have a
partial understanding of the tools the government can use to conduct
surveillance on millions of people worldwide. It’s important that this
type of information be debated in the public sphere.” But debate is
difficult, he noted, if the public lacks a meaningful sense of the
technology’s uses — let alone its existence.
A former defense intelligence official, who spoke to The Intercept on
the condition of anonymity because they were not authorized to discuss
classified material, believes the technology’s low profile is not an
accident. “The government avoids discussing this technology because it
raises serious questions they would prefer not to answer,” the official
said. “This is a critical piece of what has happened to us and our
rights since 9/11.” For the technology to work, the official noted, “you
don’t need to do anything else but open your mouth.”...MORE
