You may wonder why President Jefferson's picture is prominent on this web
site. Well, when he was the Secretary of State he invented, in cooperation
with Robert Patterson of the University of Pennsylvania, what they called a
"Wheel Cipher" wherein thirty-six wheels, each with alphabetical symbols
individually mixed and inscribed around the circumference, were placed on a
common axle. When each correspondent had an identical cylinder and the
wheels were identically, a plaintext message enciphered by one could be read
by the other. This device is described and analyzed in his papers.
There is a wheel cipher on display in the museum (pictured below) that may well have belonged to President Jefferson as it dates from that era and corresponds to his
description. Jefferson also used other methods of encryption. Interestingly
enough, the basic ideas of Jefferson's Wheel Cipher were in use even well
into the WWII period. For example, a U.S. Army "M-94" (below) is also on display in
the museum. The similarities are obvious.
Jefferson Wheel Cipher
Click on Image for an Expanded View
While the telegraph was used in both strategic and tactical uses in the U.S.
Civil War and prompted many of today's command, control, and even
'information warfare' techniques, there were accompanying needs for accurate
encryption tools. One such device that is on display in the museum is a
Confederate Cipher Reel from the 1863 time-period.
This reel, shown below, was a mechanization of the Vigerere system of polyalphabetic substitution. This rare artifact was sent to the chief signal officer in Washington as a trophy after it was captured at Mobile, Alabama. The use of tool such as this improved both the speed and accuracy of encryption and decryption processes. Of course, code books and cipher disks were also used by both sides in this conflict.
In the late 1930's U.S. Army cryptologists developed a technique of using
wired rotors to drive the relative positioning of the basic cipher rotors in
a wired rotor cipher machine. This provided great improvement in the
cryptologic security of the systems in use at that time. After a period of
evaluation, both the Army and Navy adopted this machine. It used ten rotors
for basic cipher operations and five rotors to control the stepping. The
Army and Navy could communicate securely using the same machine. Over ten
thousand of these machines, called SIGABA by the Army and ECM by the Navy,
were used during the war. Postwar analysis revealed that it had provided a
powerful advantage; the SIGABA/ECM machines were never exploited by the
enemy. One of these machines is on display in the museum and portions of its
colorful development process can be explored in the Museum Library.
Today, digital technology is the backbone of our entire information
industry. This was not the case prior to WWII. Pioneering work was performed
in this era in a successful effort to provide secure voice communications
for high-level government officials. Prior to the full involvement of the
United States in WWII, both the U.S. and the U.K. used transatlantic
high-frequency radio for voice communications. While an analog privacy
system was used, it could be exploited (and was) by a determined adversary.
A remarkable development effort, led by the Bell Telephone Laboratories
(BTL) demonstrated an entirely new way to provide voice security. A U.S.
Army contract was awarded in 1942 for the production of two systems. They
were successful and the system, called SIGSALY, was first deployed in 1943.
There were at least eight important engineering 'firsts' involved in this
system. Twelve terminals were eventually deployed.
It was a capable system, but required specially trained operators and
support personnel. The Army responded to this challenge by creating the
805th Signal Service Company and members of the Women's Army Corps also
performed many associated duties. it was also a large system; it weighed
over 55 tons! Nevertheless, the ability to use truly secure voice
communications at high organizational level was a great advantage to the
Allies in the conduct of the war and the critical time that followed it.
A mock up of a SIGSALY system is on display in the museum, one can listen to
a simulation of what the voice quality was, and a brochure is available that
describes some of the techniques that were used in that time.
Transistor circuitry found its way quickly into communications security
equipment once reliability data were obtained and good design criteria were
established. An example is the KW-7 data encryption system, an
all-transistor unit that was deployed initially in the 1960's. The
transistorized system was about one tenth the size of the system it replaced
and had much lower power consumption.
Transistors were also applied to the problem of voice security. The KY-3
voice encryption system was still too large and power-hungry for graceful
tactical field use, but it did gain wide acceptance in office-like
applications. Some of these systems remained in operation until the late
Examples of both of these systems and their successors are on display at the
museum. They represent the ever-continuing need to apply advancing
technology in large scale deployments of critical capabilities.
The examples given above are only a portion of the Information Assurance
story that is told in the museum. There are also examples of equipment and
techniques that predate President Jefferson and extend on into the space
age. When you visit, you will see examples of "paper and pencil" techniques
and those that use radiation hardened large scale integrated circuits. It
will become very clear that both the variety of applications and the
technologies continue to expand today. What is next? We invite you to visit
the museum and see if your imagination is stimulated! We think it will be.
- Last Updated - 6/11/2013
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