[an error occurred while processing this directive] Cryptographic Timeline:
 

 
Ancient Uses
1900 BC Egyptians used alternate hieroglyphs while inscribing tablets, the first documented use of written cryptography. The place was Menet Khufu, which borders the Nile river. The writer of these tablets did not use a completely different set of hieroglyphs, though. Instead, his was a system of partial substitution , with some unusual hieroglyphs (Egyptian writing) here and there.
1500 BC In Mesopotamia, cryptography surpassed that of Egypt, approaching a very modern level. The first recorded use of cryptography was in 1500BC with an encrypted formula for pottery glaze. The tablet containing the formula was only 3x2 inches and was found on the banks of the Tigris river. It used special signs which can have several different meanings. 
500 BC Scribes writing the book of Jeremiah used what is now known as the ATBASH cipher. This is one of the few ciphers of the Hebrew language. The cipher itself, ATBASH, is very similar to the substitution cipher. (A substitution cipher is one where each letter of the alphabet actually represents another letter.)
487 BC The Spartans of Greece created the first military form of cryptography. Their soldiers used a piece of wood with a strip of leather wrapped around it, a Skytale they called it. They wrote on the leather, unwrapped it from the staff, and wore it as a belt. The recipient of the message would have to have an identical stick for the letters to line up when the leather was re-wrapped.
300 BC Artha-sastra, a book attributed to Kautilya, was written in India. It recommended varieties of cryptanalysis, the process of breaking codes, to gain intelligence reports.
130 BC In Uruk, which is now known as Iraq, it was popular for scribes to turn their names into numbers within the Colophon of their works. This was most probably done just to amuse the readers, and served no security-related purpose.
50 BC Julius Caesar used his famous substitution cipher to encrypt government communications. To form his encrypted text, Caesar changed letters with a shift of three; A became D, B became E, etc. In addition, Caesar sometimes strengthened his encryption by substituting Greek letters for Latin ones.
200 AD Leiden papyrus, a work detailing how to make unusual potions, has crucial portions of the recipes enciphered. Examples of these "magic recipes" are ones that supposedly make a man love a woman, or give a man an incurable skin disease. Incidentally, they do not work. 
400 Kama Sutra of Vatsayana places cryptography as the 44th and 45th of the 64 arts that people should know and practice:
  1. The art of understanding writing in cipher, and the writing of words in a peculiar way.
  2. The art of speaking by changing the forms of the word.
725  Abu Yahmadi, creator of the first Arab dictionary, wrote a book on how he solved a Byzantine cryptographic puzzle written in Greek. His method of attack started on an assumption that the puzzle began with "In the name of god," and so he worked out the rest from that assumption. This method of attack is the same one that was employed in World War II to break German communications. 
855 Abu Wahshiyyaan-Nabati, a scholar, made public some cipher alphabets which were used for encrypted writings.
1226 In Venice, some political documents contained crosses and dots instead of words.
1250 Roger Bacon, an English Monk, wrote his book "Secret Works of Art and the Nullity of Magic." In it, he describes several simple ciphers, such as using consonants only, or "magic figures."
1392 "The Equatorie of the Planetis", which was written by Geoffrey Chaucer, uses a substitution cipher. For part of the book, Chaucer substituted letters and digits for different letters and digits.
1412 Subhalasha, an Arabic Encyclopedia, contained a section on Cryptography. Ciphers cited are substitution and transposition . Also, it mentioned running a text through multiple substitution ciphers.
1518 Johannes Trithemius wrote a book on cryptography. It was the first book on the subject to go to print. 
1553 Giovan Belaso came up with the idea of the password. He theorized about ways to encrypt text so that they could only be decrypted with the correct "password."
1563 Giovanni Porta wrote a book on ciphers in which he classified the various kinds. He said that the three types of ciphers were transposition , substitution , and symbol- substitution .
1623 Sir Francis Bacon advanced a cipher by employing one of the first uses of steganography, or hiding the fact that an encrypted message even exists. He hid his messages by slightly changing the typeface of a random text so that each bit of the code was hidden within the random text's letters.
1790s Thomas Jefferson created a wheel cipher. Unfortunately, this was lost, and the idea was re-invented for use in World War II by the US Navy, which then called it the Strip Cipher. 
1861 The first US Patent on a cryptographic device was filed. About 1,800 patents on the field have been issued since.
1861-5 The Union, during the US Civil War, used an advanced substitution cipher to encrypt communications. The specific cipher they used was strong enough for the time to ensure security of communications. The Confederacy used a less complicated cipher, which at the time was easily broken.
1891 Major Bazeries made a wheel -based cipher, and attempted to sell it to the French Army, which rejected it. Bazeries went on to publish the design in 1901
World War I
1895 Radio was invented. The importance of this to cryptology is immense. During times of War, it allowed for enemy communications to be intercepted in mass. Thus, the profession of cryptanalysis, or the breaking of encrypted messages, was born.
1914 World War I broke out. The French, being prepared, had stations already set up for intercepting German communications. They were very busy gathering messages, though, and didn't have the time or resources to decrypt them.
1914 The British began using messages that were run through cryptographic squares for their communications, and the French began using four-digit codes which represented words. 
1914

(late)

 With troops settling in place, the French were able to concentrate on decipherment. The Germans used a transposition cipher, which was very difficult to break through without the aid of a computer. However, when the French could find different messages with exactly the same length, it became possible to break them relatively easily. Once the key was discovered, the allies could continue to use it to break every German communication for the 8-10 days for which the key was in effect.
1915 The Germans changed their cipher method to complicated substitution ciphers, using 24 possible encryption alphabets, or combinations of them. These ciphers became progressively more complicated, but the French were always up to the challenge, constantly figuring out what messages said.
1916 The allies started using a "code book" in telephone communication. The Germans had been consistently intercepting wired telephone calls, because only radio-based communications were previously encrypted. Thus, after a catastrophic loss of life that resulted from a message intercept, General Dubail of France requested these "trench codes", which dictated that in normal telephone conversations, certain words be spelled out in code rather than spoken. The Germans did not start doing this in their communications for another year.
1917 The Germans, getting fed up with incredibly complicated substitution ciphers, returned again to transposition ciphers in their communication.
1917 British cryptographers broke the Zimmerman Telegram, a secret German communication to Mexico in which the Germans offered Mexico United States territory in return for joining the German cause. When the American public got wind of this, their opinion became in favor of joining the war with the allies. The United States then did this, and changed history. In his book, David Kahn says "never before or since has so much turned upon the solution of a secret message."
1917 The United States employed its first codebreaker to crack enemy communications. The man, William Frederick Friedman, was later named the father of US codebreaking (or cryptanalysis, as it is sometimes called). He later founded a school for cryptanalysis in Riverbank, Illinois.
1917 Gilbert S Vernam, an AT&T employee, created a machine that makes a non-repeating, virtually random sequence of characters (often called a one-time pad). Using an encryption key the same length as the message, and never using that key again is the only proven method of securely communicating. However, it is impractical under most circumstances because all parties must have a long and identical key, which presents a logistical nightmare for everyday use.
1918 The United States employed eight American Indians from the Choctaw tribe to relay important messages across insecure communication channels in their native tongue. Since Native American languages are extremely complex and difficult to learn, this allowed for simple and effective encryption.
 World War II
1923 Arthur Scherbius, inventor of the Enigma Machine, tried to sell it commercially. He had little luck. The German Government would eventually take it over, improve upon it, and use it to encrypt military communications in World War II.
1929 Matrix-based encryption came to be when Lester S Hill published a block of plaintext/ciphertext created with a matrix operation.
1930s The British developed the TYPEX encryption machine, based on the commercial Enigma from the 1920s. This machine contained five rotors, each of which changed letters of the alphabet to other letters. After each character of the message being encrypted was typed, the rotors changed positions, creating an entirely new encryption scheme for the next letter. Reversing the process decrypted the message.
1927-33 With prohibition, the greatest age of criminal cryptography was born. According to a report in the mid thirties, some of the cryptography employed by criminals was "of a complexity never even attempted by any government for its most secret communication." (Elizabeth Smith Friedman)
1937 The Japanese invented the PURPLE machine to encrypt messages. This machine was a totally new concept to cryptography. All machines prior to it used rotors to change the position of letters in the alphabet. Instead, the Purple Machine used telephone stepping switches, and thus standard cryptanalytic techniques were useless against it. US cryptographer William Friedman eventually broke the code generated by this machine.
1939 The allies got their first look at a German Enigma machine after Polish intelligence stole it.
1940 The Bombe, a machine that decodes Enigma messages, was invented. 
1939-42 Since ENIGMA was broken, the Battle of the Atlantic was saved, preserving countless lives.
1942 The United States began using Navajos in a manner similar to the use of the Choctaws in World War II: To speak important communications in their native language, so that the enemy could not understand. 
1944-5 The allies began using SIGABA to encrypt high level communications. SIGABA was a much-enhanced ENIGMA, and no one was able to decipher any communications encrypted with it. However, this extremely advanced machine can now allegedly be broken with modern supercomputers in approximately eight seconds.
 Modern Uses
1970 The Lucifer cipher was developed at IBM. This eventually evolved into triple-DES, an algorithm accepted worldwide as relatively secure.
1976 "New Directions in Cryptography" was published, introducing the concept of public-key cryptography, which forms the basis of internet encryption. The book also focuses on the powers of authentication via a one-way function, where the authenticator does not need to know the actual password.
1977 Ronald Rivest, Adi Shamir, and Leonard Adleman invented the RSA computer-encryption algorithm. RSA is a public key algorithm based on the difficulty of factoring large numbers. The algorithm was published in the September 1977 issue of Scientific American. Even today, it is used to keep text secret.
1984 ROT-13, a popular cipher in Usenet newsgroups, was introduced. The concept involved rotation of letters in the alphabet by thirteen. Since everyone knows the key, there is no secrecy; the idea was to encrypt objectionable material so that innocent eyes would not be subjected to it unknowingly.
1990 Mathematicians from Switzerland invented the International Data Encryption Algorithm (IDEA) to replace the aging DES. IDEA has 128 bits, meaning there are 340,282,366,920,938,463,463,374,607,431,768,211,456 possible keys. This algorithm also has the advantage of being able to be carried out quickly, because it uses math that comes naturally to computers.
1991 Pretty Good Privacy (PGP) was released by Phil Zimmerman, an American. To this day, it is considered a very secure way of communication across the internet. PGP employs a public key system so that the a recipient cannot determine the key used to encrypt the message, even if he knows the key for decrypting the message.  PGP is designed so that it can be integrated into email packages, thus allowing it to be used by the average citizen.