Glossary of common terms

This is a brief, introductory glossary of terms used in discussing the U.S. Naval Computing Machine Laboratory and the secret work at NCR. See also the Glossary which accompanied the archive of Traffic between Dayton and Op-20-G4 at Nebraska Avenue. Sources are listed below.

Battle of the Atlantic
Name given to the Allies’ efforts, from 1939 to 1945, to make the shipping routes vital to their victory safe and secure. It was not a single battle, or series of battles, but continuous planning, organization and coordination of efforts between the Allied navies.
See also the Mariners Museum Online Exhibit Battle of the Atlantic
CODES, CIPHERS
CODES and CIPHERS operate differently.
CODES are systems of making a message in plaintext secret by subsituting groups of letters or numbers for entire words or phrases. A list of the substitutions are usually contained in a codebook or a similar master list.

CIPHERS are systems of concealing a message by subsituting individual letters, numbers or symbols with other letters, numbers or symbols. Cipher systems are usually based on a key, or method of encryption.
The Germans and the Japanese used many codes and ciphers, some of which were never broken. “The Japanese possibly had more than 50; the Germans had nearly 200 ENIGMA variants alone as well as several Geheimschreiber and hand cipher systems.”

The U.S. Navy machines called “bombes,” designed and built in Dayton, were used to read German communications based on ciphers. Later machines built in Dayton to be used on Japanese communications attacked codes used by Japan.
DECIPHER
To decipher is to return an enciphered message to its plaintext form. The bombe was a machine which deciphered secret communications.
ENCRYPTION
Encryption is the process of applying a cipher (enciphering) or code (encoding). One type of encryption process is to use an algorithm.
ENCRYPTION ALGORITHM
An encryption algorithm is any general encryption process which can be specified exactly by choosing a key.
ENIGMA
Name for a cipher machine designed to mechanically encrypt plaintext. Originally was introduced in the commercial market, to be used by banks to commicate in a secure manner it was developed from a design patented by a Dutchman, H. A. Koch, in 1919. German engineer Dr. Arthur Scherbius marketed it in 1923. By 1929 the German Army and Navy were using different versions of it. Later, the Luftwaffe, the SS, the Abwehr and the German state railways also used versions of it.
JN-25
The Japanese Fleet General Purpose Code that carried the operational orders of the Combined Fleet, an enciphered code
KEY
A key is the rule which specificies the method of encryption, such as the arrangement of letters within a cipher alphabet, or the pattern of shuffling (in a way, all the Engima machine did was to shuffle the letters in a message in a way determined by settings on a machine).
NATIONAL SECURITY AGENCY (NSA)
The NATIONAL SECURITY AGENCY was established as a result of a revised version of the National Security Council Intelligence Directive (NSCID) of 1948. This revision provided that the production of COMINT (acronym for communications intelligence) was to be in an agency reporting directly to the Secretary of Defense.
Op-20
Op-20, the designation for the Office of Naval Communications, or the 20th division of OPNAV, the Office of the Chief of Naval Operations..
In January 1924, Commander Ridley McClean, Director of Naval Communication (DNC) established a research desk within the Code and Signal Section with a complement of one officer, Lieutenant Laurance F. Safford, and one civilian, Agnes Meyer, both of whom were cryptanalysts/cryptographers.

Op-20-G
Op-20-G, US Navy radio intelligence bureau; G section of Op-20. This division evolved over the years:
In the Department of the Navy:
Code and Signal Section (Op-20-G), Division of Naval Communications (DNC), OCNO (July 1922-Mar. 1935).
Communications Security Group (Op-20-G), DNC, OCNO (Mar. 1935- Mar. 1939)
Radio Intelligence Section (Op-20-G), DNC, OCNO (Mar.-Sept. 1939)
Communications Security Section (Op-20-G), DNC, OCNO (Oct. 1939- Feb. 1942)
Radio Intelligence Section (Op-20-G), DNC, OCNO (Feb.-Oct. 1942)
Communications Intelligence Organization (Op-20-G), DNC, OCNO (Oct. 1942-July 1946)
See also Op-20-G’s Subdivision Order of 14 April 1944 for more information about departments and duties
The two elements of RADIO INTELLIGENCE are:
DIRECTION-FINDING, which locates radio transmitters by turning antennas until they pick up the transmitted signal at its loudest; and TRAFFIC ANALYSIS which determines which radios are transmitting and possible lines of command.
SIS
S. I. S. was the Signal Intelligence Service of the Army, originallly headed by William Friedman.
U-boat
German submarine, Unterseeboot (undersea boat)
USNCML
United States Naval Machine Laboratory, a duty statiion at the National Cash Register Company in Dayton, Ohio. Name given to the operations at the National Cash Register Company from 1942 to 1946. The personnel were under the command of Lt. Cmdr. Ralph Meader, Bureau of Ships. From Bombe History, written by Josph Wenger, Howard Engstrom and Ralph Meader: “On 11 November 1942 the U.S. Naval Computing Machine Laboratory was established by letter from the Vice Chief of Naval Operations to the Commandant, Ninth Naval District, for the purpose of assisting the contractor in the production of these Bombes and in the training of maintenance and operation personnel.”
  • Sources
  • 1. Battle of Wits: the Complete Story of Codebreaking in World War II, Stephen Budiansky, The Free Press, 2000
  • 2. The Oxford Companion to World War II, ed. I. C. B. Dear, Oxford University Press, 2001