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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Roman smoke telegraph network, 150 A.D. The Roman smoke signals network consisted of towers within visible range of each other and had a total length of about 4500 kilometers. It was used for military signaling. For a similar telegraph network in ancient Greece see Aeneas Tacitus' optical communication system.

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