From Text to Technological Context: Medieval Arabic Cryptology's Relation to Paper, Numbers, and the Post

摘要

This article argues that papermaking supported cryptanalysis's invention; that cryptology-meaning both cryptography and cryptanalysis-could not be practiced before the sustained production of paper; and that Medieval Arabic cryptology originated in tandem with algebra. Furthermore, this article posits that the regional Islamicate postal service, or the barid, was used to relay Medieval Arabic cryptograms and thereby shaped the substance of cryptology. These conclusions stem from examining ninth century to fourteenth century Arabic cryptology as a technology and relating Arabic cryptology to three other technological devices: papermaking in the Middle East, algebra, and the band. Extant documents suggest that cryptology originated in ninth century Baghdad. This is because no cryptanalytical writings are known to exist before this period, and cryptology requires both cryptography and cryptanalysis. However, evidence of Medieval Arabic cryptology exists almost exclusively in practitioners' treatises, not in cryptograms or the working papers of cryptana-lysts. To redress this barrier to historical research, I move from text to context, or from the ideas in the treatises to thinking about the technologies these ideas called for. Placing cryptological technology within the wider technological context that inspired, shaped, and confined its development suggests why cryptology originated in the Islamicate world, how Arabic cryptology may have been implemented in practice, and what enabled cryptology's start. I hope that this technological exercise encourages the study of the context in which Medieval Arabic cryptology developed, until further primary sources surface. Furthermore, I intend to demonstrate Medieval Arabic cryptology's relevance to cryptological history and Middle Eastern studies.