[NetBehaviour] Communications Surveillance: Privacy and Security at Risk.

marc garrett marc.garrett at furtherfield.org
Sun Sep 13 18:44:11 CEST 2009

Communications Surveillance: Privacy and Security at Risk.

by Whitfield Diffie, Susan Landau.

Communications Surveillance: Privacy and Security at Risk

As the sophistication of wiretapping technology grows, so too do the
risks it poses to our privacy and security.

We all know the scene: It is the basement of an apartment building and
the lights are dim. The man is wearing a trench coat and a fedora pulled
down low to hide his face. Between the hat and the coat we see
headphones, and he appears to be listening intently to the output of a
set of alligator clips attached to a phone line. He is a detective
eavesdropping on a suspect's phone calls. This is wiretapping—as it was
in the film noir era of 1930s Hollywood. It doesn't have much to do with
modern electronic eavesdropping, which is about bits, packets, switches,
and routers.

Wiretapping Technology

Scarcely a generation ago, phone calls traveled through wires between
fixed locations, encoded as fluctuating electric signals. Now phones are
mobile, and, through most of their journeys, phone calls are encoded in
bits. Voices are digitized shortly after they leave the speaker's lips,
carried over an IP network as packets, and returned to analog for
presentation to the listener's ears.

Although big changes in telephony have given rise to equally big changes
in wiretapping, the essentials remain the same. The interception and
exploitation of communications has three basic components: accessing the
signal, collecting the signal, and exfiltrating the signal. Access may
come through alligator clips, a radio, or a computer program.
Exfiltration is moving the results to where they can be used. Collection
may be merged with exfiltration or may involve recording or listening.


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