| A | B |
|---|
| 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. |
| CODES | systems of making a message in plaintext secret by subsituting groups of letters or numbers for entire words or phrases. |
| CIPHERS | systems of concealing a message by subsituting individual letters, numbers or symbols with other letters, numbers or symbols |
| DECIPHER | to return an enciphered message to its plaintext form |
| ENCRYPTION | process of applying a cipher (enciphering) or code (encoding) |
| ENCRYPTION ALGORITHM | any general encryption process which can be specified exactly by choosing a key. |
| ENIGMA | Name for a cipher machine designed to mechanically encrypt plaintext |
| NATIONAL SECURITY AGENCY | established as a result of a revised version of NSCID, COMINT reports directly to Sec. of Defense |
| DIRECTION-FINDING | element of Radio Intelligence, locates transmitters by turning antenna until a signal is picked up |
| TRAFFIC ANALYSIS | element of radio intelligence, determines which radios are transmitting |
