• 60 BCE

# Caesar Cipher

One of the earlist known ciphers, the empiror used the cipher to communicate with his generals. The cipher was highely effective as most people of the time
• 500

# Atbash Cipher

Substitution ciphers were widely popular from the beginning of coded communication and various methods have been used from shifting. The difference about the Atbash Cipher is there was no shift, the cipher inverted the alphabet, A became Z, B become Y and so on. At the time it was useful and easy to use in today's standards the cipher is useless with it being easy broken
• Dec 24, 1466

# Polyalphabetic Cipher

Leon Battista Alberti invented the first polyaphabetic cipher. The cipher employed a cipher disk to simplify use. His cipher was uncracked until the 1800's
• Dec 24, 1518

# Polygraphiae

First book written about cryptography by Johannes Trithemius, first instance of Vigenere square.
• # Grille Method

Cardinal Richelieu utilized a method of sending secret messages. The method centered around having a card with specifically located holes that when held to a document would mask all unneeded letters leaving only the message.
• # Leibniz Calculating Machine

The device was used to encrypt text into the binary scale. This technique later became the foundation for ASCII which can still be utilized today.
• # Great Paris Cipher

Used by Napoleon and his army, consisting of over 200 code numbers and based on the ciphers of Louis XIV. The cipher however was broken by Major George Scovell in 1812.
• # Tomographic Cipher

Horace Mann defined the tomographic cipher by creating a grid system in which letters could be determined based on a row and column pairing.
• # Beale Papers

Three encrypted pages are published belonging to Beale. The pages promise to be instructions on how to find the buried treasure of Beale. To this day only one of the pages has been deciphered by using the Declaration of Independence as a book cipher.

In 1894 Marconi invented radio transmissions. While the radio transmission in and of itself was not about cryptography it did spur the need for secure communication. The technology was widely used and proved invaluable to the military.
• # Enigma Machine

Used heavily by the German army in World War II the Enigma Machine would encrypt a typed message. Various issues were found in the machine as Allied forces attempted to crack the encryption.
• # SIGSALY

Developed by A.B. Clark and others at the Bell Telephone Labs, the technology was used to encode vocal transmissions through the telephone. Used by the Allied forces in WWII it was never broken by the Germans.
• # Public Key Cryptography

Originally thought to have been created by Diffie and Hellman in 1976 the technology was developed at the UK's GCHQ. The technology employees the use of a public key which is widely known and distributed and a coresponding secret private key. The message is encrypted with the public key and since the private key is secret only the intended party can decrypt and read the message.
• # Diffie-Hellman-Merkle Key

The first use of public key cryptography. Large step forward but was somewhat of an inconvenience. See Public Key Cryptography for more information on the actual origin of public keys