Timeline BC ~ 1900 BC: Egyptian writers use non-standard Hieroglyphs in inscriptions of a royal tomb; supposedly this is not the first but the first documented example of written cryptography 1500 an enciphered formula for the production of pottery is done in Mesopotamia parts of the Hebrew writing of Jeremiah's words are written down in "atbash", which is nothing else than a reverse alphabet and one of the first famous methods of enciphering 4th century Aeneas Tacticus invents a form of beacons, by introducing a sort of water-clock 487 the Spartans introduce the so called "skytale" for sending short secret messages to and from the battle field 170 Polybius develops a system to convert letters into numerical characters, an invention called the Polybius Chequerboard. 50-60 Julius Caesar develops an enciphering method, later called the Caesar Cipher, shifting each letter of the alphabet an amount which is fixed before. Like atbash this is a monoalphabetic substitution.

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Chappe's fixed optical network Claude Chappe built a fixed optical network between Paris and Lille. Covering a distance of about 240kms, it consisted of fifteen towers with semaphores. Because this communication system was destined to practical military use, the transmitted messages were encoded. The messages were kept such secretly, even those who transmit them from tower to tower did not capture their meaning, they just transmitted codes they did not understand. Depending on weather conditions, messages could be sent at a speed of 2880 kms/hr at best. Forerunners of Chappe's optical network are the Roman smoke signals network and Aeneas Tacitus' optical communication system. For more information on early communication networks see Gerard J. Holzmann and Bjoern Pehrson, The Early History of Data Networks.

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Adi Shamir Adi Shamir was one of three persons in a team to invent the RSA public-key cryptosystem. The other two authors were Ron Rivest and Leonard M. Adleman.

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