ENCYCLOPEDIA OF Espionage, Intelligence, and Security Volume ...

Code WordA code name is a particular type of code word. A codeword is any word or phrase that has been chosen to signifya specific message while keeping that message hiddenfrom a third party. Functional codes may contain thousandsof code words, some of which may also be codenames; however, a code name need not be part of a largercode. It may, in effect, be a code unto itself, comprised ofonly one word.❚ FURTHER READING:BOOKS:Chant, Christopher. The Encyclopedia of Codenames ofWorld War II. London: Routledge & Kegan Paul, 1986.Churchouse, Robert. Codes and Ciphers. Cambridge, UK:Cambridge University Press. 2002.Mollin, Richard A. An Introduction to Cryptography. NewYork: Chapman & Hall 2001.Singh, Simon. The Code Book. New York: Doubleday,1999.SEE ALSOCode WordCodes and CiphersCodes are therefore limited in flexibility by the number ofcode words that can be fit into a code book of practical size,whereas ciphers can convey almost any written message .❚ FURTHER READING:BOOKS:Mollin, Richard A. An Introduction to Cryptography. NewYork: Chapman & Hall, 2001.Singh, Simon. The Code Book. New York: Doubleday,1999.SEE ALSOCode NameCodes and Ciphers❚ LARRY GILMANCodes and CiphersCode WordA code word is a word or phrase that is used to convey apredefined message that differs from its own literal meaning.For example, the code word IRONBOUND might beused to convey the message ”meet by the river at midnight.“If a number (e.g., 785) is used instead of a word, it istermed a code number. Both code words and code numbersare also termed code groups.A code is comprised of a list of messages and thecode groups that have been defined for them, usuallywritten down in parallel columns in a codebook. To createor interpret messages in a code, one must have access toits codebook. One advantage of a code, as compared to acipher, is that a single code group may contain a variableamount of information, even within a single code; thecode word IRONBOUND, above, conveys a complete command,while another code word might stand either for asingle word or for an entire plan of operation. This makes awell-designed code difficult to crack by examining capturedmessages for patterns.Word codes, however, also have disadvantages. Firstand foremost, if a copy of the codebook falls into enemyhands, then the code becomes useless. Second, onlyideas for which code words have been predefined can becommunicated using a given code. For example, if a codebook contains no code word for ”noon,“ it may be impossibleto convey the message, ”meet by the river at noon.“Codes and ciphers are forms of cryptography, a term fromthe Greek kryptos, hidden, and graphia, writing. Bothtransform legible messages into series of symbols that areintelligible only to specific recipients. Codes do so bysubstituting arbitrary symbols for meanings listed in acodebook; ciphers do so by performing rule-directed operationsdirectly on original message text. Because codescan only communicate concepts that are listed in theircodebooks, they have limited flexibility. Rather, moderncryptography relies almost entirely on ciphers implementedby digital computers, and is widely employed inindustry, diplomacy, espionage, warfare, and personalcommunications.Codes. A code is a set of symbolic strings (”code groups“)that are listed, along with their assigned meanings, in acode book.Codes encrypt messages by substitution, that is, theysubstitute code groups for components of the originalmessage. ”Kill the king at midnight“ could thus be encoded,for example, as ”OAKEN 7890 SPINDRIFT.“ Withoutthe code book, it would be difficult for a reader of theencoded message to form an idea of its meaning.Either a word or a number can be used as a codegroup. Code groups that are words are termed code wordsand those that are numbers are termed code numbers.Note that a single code group can encode a single word(”king“) or an entire phrase (”deliver the films to agentnumber 3“). A coded message may, therefore, be shorterthan the original message. It can also be made as long asor longer than the original message, if the codebook224 Encyclopedia of Espionage, Intelligence, and Security