Goniometry, Enciphering, Deciphering and the Father of Cryptology
February 15, 2013
In the 1886 annual report by Chief Signal Officer Benjamin F. Fisher, he envisioned the Signal Corps not only providing communications, but also acting as the military intelligence bureau. This exact scenario never played out, but intelligence and cryptanalysis were significant parts of CECOM's organizational heritage, especially during the WW I.
The enciphering and deciphering of messages, according to specified codes, was included in the curriculum of the Signal School since 1912.
Although cryptography was used, the Signal Corps had not strictly practiced communications security prior to the First WW I. The War Department Telegraph Code of 1915 had chiefly served to reduce the length of transmissions, rather than as a means to assure their secrecy.
To enforce security, listening stations monitored friendly traffic for lapses in procedure. While signal officers performed cryptography, military intelligence officers conducted cryptanalysis, or the breaking of unknown codes.
In the Army Expeditionary Forces (AEF), however, the office of the Chief Signal Officer included a Code Compilation Section where officers devised the so-called River and Lake Codes, which were distributed to the First and Second Armies, respectively, for use in both wire and wireless communications.
While still a Captain, the future "father of modern American cryptology," Parker Hitt, knowing the U.S. Army field cipher was insecure, designed a more secure system as a replacement in 1914. In 1917, the Signal Corps widely adapted Colonel Hitt's cylindrical device and it remained in service the better part of three decades.
On the eve of WWI, Hitt applied for a two-year assignment to the Signal Corps. While teaching at the Army Signal School, he researched and wrote his groundbreaking work, The Manual for the Solution of Military Ciphers. Published in 1916, his book was the first work of its kind in the United States in 100 years and laid the foundation for the nation's unmatched cryptologic achievements during the 20th century.
During the period of tension with Mexico, which culminated in Pershing's Punitive Expedition, Col. Hitt and his wife, Genevieve Young Hitt, "moonlighted" to solve intercepted messages. He gained a well-deserved reputation as one of the Army's most talented codebreakers, and Gen. Pershing selected him to be a member of his staff when the American Expeditionary Force deployed to France in 1917.
As a Senior Signal Officer with the AEF during WW I, Hitt oversaw the compilation of a highly effective code that replaced an awkwardly translated French coding system that was being used by American forces. He also supervised units that intercepted sensitive German communications with impressive results.
Historian Rebecca Raines from the U.S. Army Center for Military History wrote, "Radio's chief role was for intelligence purposes… signalmen on the ground used their radios to obtain information about the enemy." Signalmen during the First World War intercepted German ground radio communications, operated intercept stations, and even listened in on telephone and telegraph traffic.
In retirement during the 1940s, Hitt was an informal liaison between the Army and members of the American Cryptogram Association, but was anxious to serve in the war. Hitt returned to active duty from 1940 to 1944 as a corps area Signal Officer.
Using goniometry, or direction finding by means of measuring angles, Signal Corpsmen also obtained bearings on enemy radio transmitters so the location of the stations could be identified. A goniometer is a radio receiver and directional antenna used as a system to determine the angular direction of incoming radio signals. Goniometric stations could also detect incoming airplanes from their radio signals. Furthermore, from the amount of radio traffic, the strength of enemy troops could be determined.
Radios could also be used to divert the Germans away from where attacks were being planned by broadcasting false radio traffic. The Signal Corps successfully exercised this ploy prior to the resumption of the offensive along the Meuse on Nov. 1, 1918. The radio section of the Signal Corps worked closely with the radio intelligence section of the General Staff, passing along the information it collected for transcription and analysis regarding enemy operations and intentions.
Among its many duties, the Signal Corps was responsible for revising and compiling all codes and ciphers used by the War Department and the Army. This expanded during after WWI and led to success in WWII. CECOM's continued intelligence, surveillance, and reconnaissance missions are built on the foundation of this early work.
At a time when the nation had no formal cryptologic service, CECOM's predecessor organizations performed innovative tasks and developed principles that would be used to protect U.S. military communications for decades.