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'''Cryptography''' is the enciphering and deciphering of messages in secret code or cipher. <ref>[http://www.merriam-webster.com/dictionary/cryptography cryptography from Merriam-Webster]</ref> {{etymology|From Greek "''kryptos''", meaning "hidden",<ref>[http://www.etymonline.com/index.php?term=cryptography "cryptography" from Online Entymology Dictionary]</ref> and "''graphein''", meaning "to draw" or "to write"<ref>[http://www.etymonline.com/index.php?term=-graphy "graphy" from Online Entymology Dictionary]</ref>}}

'''Cryptography''' is the enciphering and deciphering of messages in secret code or cipher.<ref>[http://www.merriam-webster.com/dictionary/cryptography cryptography from Merriam-Webster]</ref> {{etymology|From Greek "''kryptos''", meaning "hidden",<ref>[http://www.etymonline.com/index.php?term=cryptography "cryptography" from Online Entymology Dictionary]</ref> and "''graphein''", meaning "to draw" or "to write"<ref>[http://www.etymonline.com/index.php?term=-graphy "graphy" from Online Entymology Dictionary]</ref>}}

==General Information==

==General Information==

====Ancient Egypt====

====Ancient Egypt====

During the early years of the Old Kingdom of Ancient Egypt, archaeologists have found basic examples of encrypted hieroglyphs, in which certain symbols were exchanged for other seemingly nonsensical characters that, at first glance, appeared only to obscure the meaning of the text. However, it is primarily assumed that these substitutions were not made to cloister or protect critical information, but rather to provide enjoyment for the literate and intellectual members of the community.<ref name="codebook">Simon Singh, ''The Code Book''</ref>

During the early years of the Old Kingdom of Ancient Egypt, archaeologists have found basic examples of encrypted hieroglyphs, in which certain symbols were exchanged for other seemingly nonsensical characters that, at first glance, appeared only to obscure the meaning of the text. However, it is primarily assumed that these substitutions were not made to cloister or protect critical information, but rather to provide enjoyment for the literate and intellectual members of the community.<ref name="codebook"/>

====Ancient Greece====

====Ancient Greece====

====China====

====China====

Because the ancient Chinese language, like its modern day equivalents, was composed of a set of symbols that represented varying syllables, tones, and ideas,<ref name="ancientchinese">[http://www.donet.com/~rcooper/museum/search/misc/aclsc.htm Ancient Chinese Language Supports Creation]</ref> it readily lent itself to a language of the cryptographic arts. Messages would be altered based on content, tone, and similarity between symbols to messages unrecognizable to other factions at the time or people without advanced knowledge of the language.<ref name="shorthistory"></ref>

Because the ancient Chinese language, like its modern day equivalents, was composed of a set of symbols that represented varying syllables, tones, and ideas,<ref name="ancientchinese">[http://www.donet.com/~rcooper/museum/search/misc/aclsc.htm Ancient Chinese Language Supports Creation]</ref> it readily lent itself to a language of the cryptographic arts. Messages would be altered based on content, tone, and similarity between symbols to messages unrecognizable to other factions at the time or people without advanced knowledge of the language.<ref name="shorthistory" />

====Rome====

====Rome====

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Decoding a message encrypted with the Caesar cipher follows a similar process, but decryption is possible by shifting an encoded message two characters to the ''left'', in an exact reversal of the encryption process.<ref name="shorthistory"></ref>

Decoding a message encrypted with the Caesar cipher follows a similar process, but decryption is possible by shifting an encoded message two characters to the ''left'', in an exact reversal of the encryption process.<ref name="shorthistory" />

By encoding his battle plans, as well as the instructions to the commanders in the field, Caesar was able to hide his objectives from regional enemies and further the expansion of the Roman Empire.

By encoding his battle plans, as well as the instructions to the commanders in the field, Caesar was able to hide his objectives from regional enemies and further the expansion of the Roman Empire.

Although many examples of the simple substitution ciphers doubtlessly existed throughout the Middle Ages, few records of advancements in the cryptographic arts remain from the time period. However, near the end of the Middle Ages, the science of cryptography began to progress, albeit slowly at first. As powerful nation-states began to rise from the feudal predecessors, cryptography and the study of encryption began increasing in importance.

Although many examples of the simple substitution ciphers doubtlessly existed throughout the Middle Ages, few records of advancements in the cryptographic arts remain from the time period. However, near the end of the Middle Ages, the science of cryptography began to progress, albeit slowly at first. As powerful nation-states began to rise from the feudal predecessors, cryptography and the study of encryption began increasing in importance.

====Italy====

====Italy====

The first and most important advances in the study of cryptography during this time period were made in [[Italy]].<ref name="shorthistory"></ref> The city-state of [[Venice]] was the first of the regional Italian governments to dedicate a part of its government solely to the study and advancement of cryptographic techniques. As many other countries adopted these so-called "black chambers," it became more and more important to protect diplomatic communications between monarchs, ambassadors, and other governing officials.

The first and most important advances in the study of cryptography during this time period were made in [[Italy]].<ref name="shorthistory" /> The city-state of [[Venice]] was the first of the regional Italian governments to dedicate a part of its government solely to the study and advancement of cryptographic techniques. As many other countries adopted these so-called "black chambers," it became more and more important to protect diplomatic communications between monarchs, ambassadors, and other governing officials.

As the influence of the Renaissance became increasingly apparent and widespread throughout European civilization, so to did cryptography. In what is now regarded as one of the most important moments in the history of cryptography, [[Leon Battista Alberti]], now regarded as the "Father of Western Cryptology," contributed several years of his life towards the development of [[poly-alphabetic substitution ciphers]]. By designing a cryptographic system that used, in the encrypted message, used different letters in different places for the same letter in the original message, he defeated the most common tactic of cryptanalysis at the time:  frequency analysis.

As the influence of the Renaissance became increasingly apparent and widespread throughout European civilization, so to did cryptography. In what is now regarded as one of the most important moments in the history of cryptography, [[Leon Battista Alberti]], now regarded as the "Father of Western Cryptology," contributed several years of his life towards the development of [[poly-alphabetic substitution ciphers]]. By designing a cryptographic system that used, in the encrypted message, used different letters in different places for the same letter in the original message, he defeated the most common tactic of cryptanalysis at the time:  frequency analysis.

In 1553, Giovan Batista Belaso extended Trithemius' technique by restarting the keyword after every individual letter in the original message. This varied the size of the text between the length of each text, so without prior knowledge of the beginning text, decryption by the means available at the time became virtually impossible.

In 1553, Giovan Batista Belaso extended Trithemius' technique by restarting the keyword after every individual letter in the original message. This varied the size of the text between the length of each text, so without prior knowledge of the beginning text, decryption by the means available at the time became virtually impossible.

The event that thrust cryptography into the modern age, however, and caused governments and armies around the world to take notice occurred in 1628, with the Frenchman Antoine Rossignol's defeat of a Hugenot army by decoding a captured message that detailed their coming deployment plans. Soon after his victory, the French government began asking him to solve numerous ciphers, and other nations and city-states began forming dedicated organizations to break ciphers and protect information.<ref name="briefhistory"></ref>

The event that thrust cryptography into the modern age, however, and caused governments and armies around the world to take notice occurred in 1628, with the Frenchman Antoine Rossignol's defeat of a Hugenot army by decoding a captured message that detailed their coming deployment plans. Soon after his victory, the French government began asking him to solve numerous ciphers, and other nations and city-states began forming dedicated organizations to break ciphers and protect information.<ref name="briefhistory" />

===World War I===

===World War I===

====Zimmermann Telegram====

====Zimmermann Telegram====

:''Main article:'' [[Zimmermann Telegram]]

:''Main article:'' [[Zimmermann Telegram]]

In the opening days of World War I, the British navy severed every German and Austrian telecommunications line leading through the Atlantic, thus forcing the Germans to send all messages destined for the states, including diplomatic communications, through American-owned cables.<ref name="briefhistory"></ref> This caused significant problems for the German high command later in the war, because without their own dedicated cables, their messages were subjected to American interception and cryptanalysis.

In the opening days of World War I, the British navy severed every German and Austrian telecommunications line leading through the Atlantic, thus forcing the Germans to send all messages destined for the states, including diplomatic communications, through American-owned cables.<ref name="briefhistory" /> This caused significant problems for the German high command later in the war, because without their own dedicated cables, their messages were subjected to American interception and cryptanalysis.

In January, 1917, two cryptanalysis working for Room 40, the American equivalent of the European "black chambers," successfully deciphered the majority of a telegram from the German State Secretary of Foreign Affairs, Arthur Zimmermann, asking the Mexican president to intervene in the war on the German side, as well as request the same from the Japanese military.<ref name="zimmermann">[http://www.archives.gov/education/lessons/zimmermann Teaching with Documents: The Zimmermann Telegram]</ref> The decipherment of this message convinced the United States to enter into the war against the Germans, dramatically shifting the odds against Germany. According to [[David Kahn]], the foremost American historian of classical and early modern cryptography<ref name="kahn">[http://david-kahn.com/david-kahn-biography.htm Biography of David Kahn]</ref><ref name="kahn2">[http://hnn.us/roundup/comments/7460.html David Kahn: Historian of Secret Codes]</ref>,

In January, 1917, two cryptanalysis working for Room 40, the American equivalent of the European "black chambers," successfully deciphered the majority of a telegram from the German State Secretary of Foreign Affairs, Arthur Zimmermann, asking the Mexican president to intervene in the war on the German side, as well as request the same from the Japanese military.<ref name="zimmermann">[http://www.archives.gov/education/lessons/zimmermann Teaching with Documents: The Zimmermann Telegram]</ref> The decipherment of this message convinced the United States to enter into the war against the Germans, dramatically shifting the odds against Germany. According to [[David Kahn]], the foremost American historian of classical and early modern cryptography,<ref name="kahn">[http://david-kahn.com/david-kahn-biography.htm Biography of David Kahn]</ref><ref name="kahn2">[http://hnn.us/roundup/comments/7460.html David Kahn: Historian of Secret Codes]</ref>  

<blockquote>''"No other single cryptanalysis has had such enormous consequences. ... Never before or since has so much turned upon the solution of a secret message".''<ref name="zimmermann"></ref></blockquote>

<blockquote>''"No other single cryptanalysis has had such enormous consequences. ... Never before or since has so much turned upon the solution of a secret message".''<ref name="zimmermann" /></blockquote>

====The One Time Pad and Perfect Cryptography====

====The One Time Pad and Perfect Cryptography====

Coinciding with the final days of World War I, United States Army Major Joseph Mauborgne, the current head of Room 40 and all cryptographic research for the United States, suggested the possibility of encrypting a message using a truly random key. By printing two identical pads with a random key, then using that key to encrypt one message and one message alone, this cipher obliterated the past problems with poly-alphabetic ciphers:  the repetition of the key. Assuming that each random key, and therefore each set of pads, were only used one time, this encryption system formed the first and to this day only known cryptographic algorithm, or cryptosystem, that provides perfect secrecy.<ref name="briefhistory"></ref><ref name="shorthistory"></ref><ref name="codebook"></ref>

Coinciding with the final days of World War I, United States Army Major Joseph Mauborgne, the current head of Room 40 and all cryptographic research for the United States, suggested the possibility of encrypting a message using a truly random key. By printing two identical pads with a random key, then using that key to encrypt one message and one message alone, this cipher obliterated the past problems with poly-alphabetic ciphers:  the repetition of the key. Assuming that each random key, and therefore each set of pads, were only used one time, this encryption system formed the first and to this day only known cryptographic algorithm, or cryptosystem, that provides perfect secrecy.<ref name="codebook" /><ref name="briefhistory" /><ref name="shorthistory" />

===World War II===

===World War II===

After seeing the unbridled success of the cryptographic sciences in the First World War, more and more governments began investing considerable effort in the study, both to decipher information intercepted from foreign nations and to make their own messages more secure against these tactics.

After seeing the unbridled success of the cryptographic sciences in the First World War, more and more governments began investing considerable effort in the study, both to decipher information intercepted from foreign nations and to make their own messages more secure against these tactics.

A significant example of the power of decipherment and the benefits derived from research into cryptography came on April 13, 1943, during the height of America's war against Japan. The visiting commander in chief of Japanese naval forces in the Pacific, Admiral Yamamoto, forwarded his itinerary to the Japanese naval fleet. When an American listening station in Hawaii intercepted the message and decoded it, the United States seized the opportunity, and less than a week later, downed Yamamoto's plane as it prepared to leave a Japanese runway. Through a direct application of cryptography, the American Navy had killed one of the most powerful and beloved figures in the Japanese military, thus striking a critical blow to the morale of the Japanese.<ref name="briefhistory"></ref>.

A significant example of the power of decipherment and the benefits derived from research into cryptography came on April 13, 1943, during the height of America's war against Japan. The visiting commander in chief of Japanese naval forces in the Pacific, Admiral Yamamoto, forwarded his itinerary to the Japanese naval fleet. When an American listening station in Hawaii intercepted the message and decoded it, the United States seized the opportunity, and less than a week later, downed Yamamoto's plane as it prepared to leave a Japanese runway. Through a direct application of cryptography, the American Navy had killed one of the most powerful and beloved figures in the Japanese military, thus striking a critical blow to the morale of the Japanese.<ref name="briefhistory" />

The Japanese continued to use a similar cryptographic system, however, still blissfully unaware of the fact that the American researchers had long since broken it completely. Because of this overwhelming American advantage in both knowledge and warning of attacks, the United States was able to fend off a massive Japanese assault near the Midway Islands, now infamous as the site of the Battle of Midway.

The Japanese continued to use a similar cryptographic system, however, still blissfully unaware of the fact that the American researchers had long since broken it completely. Because of this overwhelming American advantage in both knowledge and warning of attacks, the United States was able to fend off a massive Japanese assault near the Midway Islands, now infamous as the site of the Battle of Midway.

====European Theater====

====European Theater====

In the European theater of World War II, a British-run group of cryptanalysts, consisting mostly of Polish mathematicians that had fled their home country before the outbreak of the war, enjoyed great success in 1942 when they first broke the codes of the German Enigma machines.<ref name="briefhistory"></ref> Although the decoded information often revealed crucial parts of the German war strategy to the Allies, the paranoia and overly suspicious nature of the Nazi commanders led them to practice extreme security with their codes and ciphers alike. <ref name="shorthistory"></ref>

In the European theater of World War II, a British-run group of cryptanalysts, consisting mostly of Polish mathematicians that had fled their home country before the outbreak of the war, enjoyed great success in 1942 when they first broke the codes of the German Enigma machines.<ref name="briefhistory" /> Although the decoded information often revealed crucial parts of the German war strategy to the Allies, the paranoia and overly suspicious nature of the Nazi commanders led them to practice extreme security with their codes and ciphers alike.<ref name="shorthistory" />

==Modern Cryptography==

==Modern Cryptography==

==See Also==

==See also==

* [[List of military strategies and concepts]]

* [[List of military strategies and concepts]]

* [[Encryption]]: [[Cryptography]]-[[Cryptanalysis]]-[[Cryptology]]-[[Data encryption]]-[[Public-key encryption]]

* [[Encryption]]: Cryptography-[[Cryptanalysis]]-[[Cryptology]]-[[Data encryption]]-[[Public-key encryption]]

* [[Unalienable rights]] of the [[Bill of Rights]]: [[First Amendment]], [[Fourth Amendment]], [[Fifth Amendment]]

* [[Unalienable rights]] of the [[Bill of Rights]]: [[First Amendment]], [[Fourth Amendment]], [[Fifth Amendment]]

* [[Right to Privacy]]

* [[Right to Privacy]]

==External Links==

==External links==

[http://www.pbs.org/wgbh/nova/sciencenow/3411/03.html Kryptos]

* [http://www.pbs.org/wgbh/nova/sciencenow/3411/03.html Kryptos]

[[Category:Privacy]]

[[Category:Privacy]]