The Puzzle Palace: A Report on America's Most Secret Agency
James Bamford, Penguin Books, 1983.
[A] foursome of inventors in Seattle, working in
their spare time in the back of a garage, managed to develop a
new type of voice scrambler. Led by thirty-five-year-old Carl Nicolai,
a job-shopper, or technical "Kelly girl," the group called its new
invention the Phasorphone and submitted a patent application in
October 1977. In April 1978, Nicolai finally received a response
from the Patent Office. But when he opened the letter, he was stunned
Instead of a patent, his hands held a strange form with the words
SECRECY ORDER in large bold letters across the top.
Nicolai had suddenly been assaulted with one of the oldest weapons
in the nation's national security arsenal: the Invention Secrecy Act.
[...]
Nicolai's secrecy order told him little except that he faced two
years in jail and a $10,000 fine for disclosing any aspect of his
device "in any way to any person not cognizant of the invention
prior to the date of the order." Nowhere on the order did it say
why it was issued or who ordered the action.
[...]
The object of Nicolai's patent application and the NSA's anxiety
was a voice privacy system that relied more, apparently, on the
science of transmission security than cryptography. As opposed to
cryptography, which merely renders the contents of a message
unintelligible to those without the key, transmission security
conceals the very existence of the message itself. The seed for
the Phasorphone was planted in 1960 in
an article on communications security by Alfred Pfanstiehl for Analog magazine.
Pfanstiehl suggested that instead of the traditional method of transmission,
where signals are sent between transmitter and receiver over a
single frequency, a system of pseudorandom wave forms be used.
Under such a system a code could be devised using pseudorandom
alterations of the frequency spectrum exactly synchronized between
transmitter and receiver. The system held promise for an area
particularly vulnerable to eavesdropping: CB and marine band radio.
But it could also be modified for telephone.