Steganographia (Secret Writing), by Johannes Trithemius. 1500.
This is Trithemius' most notorious work. On the surface it is a system of angel magic, but within is a highly sophisticated system of cryptography. It claims to contain a synthesis of the science of knowledge, the art of memory, magic, an accelerated language learning system, and a method of sending messages without symbols or messenger. Read more
Johannes Trithemius (1 February 1462 - 13 December 1516), born Johann Heidenberg, was a German abbot, lexicographer, historian, cryptographer, polymath and occultist who had an influence on later occultism. The name by which he is more commonly known is derived from his native town of Trittenheim on the Mosel in Germany. Read more