1940 to 1949: Computing During World War II and the Postwar Era - The Technical and Social History of Software Engineering - page 50

Analog Espionage
Some of the technology for the German bombsight was based on
the American Norden bombsight that had apparently been passed
to Germany by the infamous Duquesne spy ring started by Fredrick
Duquesne.
Thirty-four people were tried and convicted of espionage in
1941, the largest spy case in U.S. history. (A 1945 motion picture,
The House on 92nd Street , was based on this spy ring, and it won an
Academy Award for original motion picture story.) However, an-
other source on Wikipedia says that the Norden data was passed to
Germany in 1938.
The German government largely ignored digital computing, a technology that
actually changed the outcome of World War II. Of course, Germany was a pioneer
in other military technologies such as jet engines and field artillery. Germany also
built the famous Enigma cypher machine, which turned out to be less secure than
the German government thought it was. The Enigma machine resembled a type-
writer and its codes were created with mechanical wheels.
Germany also had another military encoding system named FISH that was elec-
tromechanical. This was usually reserved for high-level communications between
Berlin headquarters and various army headquarters, while the Enigma was used
for more frequent operational communications. The FISH machines were less
common and less well known than the Enigma machines.
The FISH machines were designed by the company of C. Lorenz in Berlin. The
machine used a stream cipher and was built as an attachment to a standard tele-
printer. There were several models produced between 1941 and 1944.
The coding system used by the FISH machines was based on a method devised
by Gilbert Vermam of AT&T Bell Labs in 1917. The cipher system used methods
of symbolic logic from George Boole's work with emphasis on the “exclusive or”
function. Several other researchers developed similar codes.
In August 1941, a FISH message of 4,000 characters was intercepted by the
British. Using manual precomputer analysis, Brigadier John Tillman and the math-
ematician Bill Tutte were able to crack the code and reverse-engineer the FISH
machine, a remarkable achievement. This work later fed into the design of com-
puters to speed up decryption.