Origins of Cryptology: the Arab Contributions

Recently discovered old manuscripts show that the origin of cryptology, and the Arab contributions to it, are older and more extensive than previously thought. The word ‘cipher’ in European languages comes from the Arabic word sifr. The 9th-century Arab scientist al-Kindī is the author of the oldest known book on cryptology, antedating any other by more than 300 years. This paper highlights the specific contributions of some Arab cryptologists based on newly discovered documents that include books of al-Kindī, ibn Adlān and ibn ad-Duraihim. Factors behind the emergence and advancement of Arab cryptology are discussed. The discoveries reported in this paper push the frontiers of the history of cryptology back by about 500 years.