Cryptography encompasses use of letters, numbers, symbols, and words to form coded messages.
Cryptography encompasses use of letters, numbers, symbols, and words to form coded messages. Military personnel utilize cryptography to transmit orders to officers and troops on land, sea, or in air as well as to mislead enemies who intercept messages. Historians have analyzed the role of cryptography in warfare, often soon after major conflicts occurred, with scholars revising interpretations as information regarding secret code-breaking work became declassified and participants divulged their contributions. World War II and espionage were the focus of much historical scholarship examining cryptography in the late twentieth century. Early twenty-first century histories discussed digital aspects of encrypting military information and assessed cyber vulnerabilities affecting military forces.
Since ancient times, military forces have benefited from various forms of cryptography, which allows sensitive information to be transmitted without informing the enemy and which can also deliberately misinform the enemy, in the effort to win battles and wars. Codes disguising military information have enabled victories over enemies who were unaware when and where troops would attack, their strength, and other crucial facts. Moreover, the ability to intercept and decipher enemies’ encrypted messages has alerted commanders to invasions so they can plan defenses and revise strategies. Military cryptanalysts have deciphered enemy messages regarding destruction of supply lines necessary for transportation of both military and civilian resources so officers could order strikes to stop enemies before they could act. Military leaders unaware of their opponents’ plans have often experienced defeat.
A four-rotor Enigma machine.
Warfare has been influenced by cryptography for centuries. Although applications have varied, military forces in different eras have appropriated universal aspects of cryptography to transmit secret information. Basic ciphers often involved substitution of letters in a word or the rearrangement of their order. The frequency of specific letters and patterns has alerted cryptanalysts to the enemy’s encoding key, so they could convert the remaining letters. Some cryptographers assigned words unique codes, which they recorded in code books accessible to people composing messages and translating them; code books were vulnerable to being misplaced or theft by enemies. Knowledge of keys became essential for effective cryptography.
Ciphers and techniques associated with cryptography advanced as people recognized more complex ways to conceal messages with elaborate combinations of codes and sophisticated technology, such as machines and computers, devised to generate or decipher coded messages. Military cryptographers have constantly sought more secure encryption methods to outwit code breakers.
Humans in ancient civilizations first utilized cryptography to protect secrets in communications from economic and political rivals, particularly during combat. Early methods often relied on people’s insights regarding how to confuse enemies.
Other Romans used transposition ciphers, which rearranged letters to create nonsensical words or entire sentences that confused enemy readers. Most ancient cryptographic systems were vulnerable to being unraveled by the enemy, who occasionally would decode messages when recognizing the correct order of letters in a jumbled word or analyzing messages for patterns of the most common vowels and consonants, which could help determine the cipher technique that had been applied to a message.
Ancient historians such as Plutarch and Herodotus recorded incidents involving secret messages and cryptographic devices associated with warfare. For example, the
During the Middle Ages, mathematicians and scientists created methods of encryption that were more complex than their ancient predecessors. Many of these encoded messages were used in military communications to outwit increasingly adept code breakers. By the late fourteenth century, governments were using ciphers for diplomatic correspondence in an effort to thwart spies.
In Italy, architect and
The Italian city-states sought cipher experts to create keys for codes and read rivals’ messages, appointing people to positions of cipher secretary and cryptanalyst. In
In the seventeenth century, French cryptologist
A letter of recommendation for a Navajo enlistee emphasizes his ability to speak the Navajo dialect, which is “completely unintelligible to all other tribes and all other people.”
By the nineteenth century, technological advances were having a great impact on military cryptography. The
Comanche code talkers for the Fourth Signal Company, U.S. Army Signal Center, Ft. Gordon.
Modern warfare involved numerous cryptography experts and events. During
In the Pacific,
Bletchley Park, north of London, where the Enigma codes were cracked.
Military cryptography embraced emerging technological advances, such as those of the digital revolution. Code experts applied mathematical functions, such as algorithms, to encode and decipher information digitally. The U.S. Military Academy’s mathematical science department began publishing the journal Cryptologia in 1977. Codes were used to protect nuclear materials, electronic data associated with military procedures and records, and the Milstar satellites deployed for military communications.
Cryptography was utilized in the
Modern communication monitoring really hit its stride with the Persian
Churchhouse, Robert F. Codes and Ciphers: Julius Caesar, the Enigma, and the Internet. New York: Cambridge University Press, 2002. A chronological discussion of cryptography from its ancient origins through the early twenty-first century, noting military and espionage applications. Copeland, B. Jack, ed. Colossus: The Secrets of Bletchley Park’s Codebreaking Computers. New York: Oxford University Press, 2006. Articles written by cryptography experts include perspectives from such prominent figures as Thomas H. Flowers, describing technological developments to decipher Enigma messages. Kahn, David. The Reader of Gentlemen’s Mail: Herbert O. Yardley and the Birth of American Codebreaking. New Haven, Conn.: Yale University Press, 2004. In this pioneering military cryptanalyst’s biography, a renowned cryptography historian offers insights and corrects errors in the cryptography literature that are often reiterated. Kozaczuk, Władysław, and Jerzy Straszak. Enigma: How the Poles Broke the Nazi Code. New York: Hippocrene Books, 2004. Examines Polish mathematicians’ cryptography training and accomplishments, the Polish Cipher Bureau, and their impact on British cryptanalysts. Meadows, William C. The Comanche Code Talkers of World War II. Austin: University of Texas Press, 2002. Comprehensive study of Native Americans who served Allied military forces by using their languages to encipher and translate messages. Showell, Jak P. Mallmann. German Naval Code Breakers. Annapolis, Md.: Naval Institute Press, 2003. This illustrated history presents details unavailable in most secondary sources regarding the German Naval Radio Monitoring Service intercepting Allied communications in warfare.
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