The first three centuries of
Islamic civilization focused on the acquiring of
knowledge and
learning from other
civilizations, past and present, through copious book acquisition and
translation. From 700-1000 AD works were gathered from all over the known world (
the art of
paper making came to
Baghdad at about this time from the
Chinese via
Indian trade-routes
1) - books usually were taken by a) force through
conquest, b)
stealth through well funded bibliophile thieves, c) greed through offered
wealth, whether real or promised, d) co-operation through scholarly
exchange or e) dumb luck (books and their owners tended to wander during this period, as learned men were simultaneously
politically dangerous yet much in
demand- so stumbling across new folks with new books wasn't unusual, despite cultural divides). Subjects of particular fascination for the Islamic scholars included
philosophy,
astronomy,
mathematics,
physics,
history and
poetry.
One huge problem the translation effort encountered through as that many of the languages encountered in the books, as they flooded via the
Caliph's agents
around the world, were completely unknown in
Arabia, or
dead languages nobody could remember. The were in essence
ciphertext (in the argot of
crypto)
and so with their knowledge of mathematics (borrowed at first from India, where concepts such as the
zero,
decimal,
algorithm,
algebra and
statistical
analysis were already well-known, though they would not reach
Europe for another six centuries) the
Arab scholars began setting down rules for textual
decryption.
2
The pivotal work of Arabic
cryptology was written by
ibn ad-Duraihim (1312-1361) entitled
Miftãh al-Kunuz fî Idah al marmûz (
The Treasured
Key for Clarifying Ciphers), which was reprinted recently in Arabic and awaits translation into English (it appears in a compilation,
Origins of Arab
Cryptography and Cryptanalysis3, which itself is an elaboration of an older text written by
Abu al-Khalîl (718-786), the
Kitab al
Mu'ammã (
The Messenger of the Caliph?) which has only ever been mentioned in later works and is considered a
lost book, likely a victim of time.
al-Khalîl was trained primarily as a
linguist, but as the unknown languages, scripts and dialects flooded into his study by order of the Caliphate, he developed the
idea of the
dictionary and an
index of coincidence for tracking
letter frequency and combinations for various languages. Then came
Al-Khwãrrizmi
(750-847), who was of particular significant to the West in somuch as it was his works (translated in
Cordoba into
Latin by the Englishman
Robert of Chester
(12th c.) under the title
Algebra et Almucaba) which gave Europe the
zero and
decimal system, and the means to finally replace
Roman numerals with
the
arabic numeral (which, as you can imagine, would make complex math even more of a drag). Finally,
Abu Yûsûf al-Kindï, head
librarian at the
Bait al-Hikmah wrote a treatise on statistical
cryptanalysis using
letter frequency entitled
Risalah fí Istikhraj al-Mu'amma, which was unearthed in the 1980s in
the Sulaimaniyyah
Ottoman Archive in
Istambul.
Notes:
1. At this point, papyrus and parchment were the only written media for most of the Mediterranean world. Before that it had been clay tablets & sticks (Babylon) or
public monuments (Code of Hammurabi).
2. The other part of the necessity for this was that some attempts at enciphering were already known, like straight-forward substitution or the Caesar cipher, and used
by certain sects: the Magi (left over Zoroastrian priests on the run from suspicion and persecution) and scholars of controversial theology, alchemy or sorcery. By
writing their texts in a code, however rough, they could keep dangerous knowledge out of the hands of their enemies.
3. Full title as it appears in Library of Congress -- `Ilm al-ta`miyah wa-istikhr¯aj al-mu`ammá `inda al-`Arab / dir¯asat wa-tahq¯iq Muhammad Mar¯ay¯at¯i,
Yahyá M¯ir `Alam, Muhammad Hass¯an al-Tayy¯an ; taqd¯im Sh¯akir al-Fahh¯am. Damascus : Majma` al-Lughah al-`Arab¯iyah bi-Dimashq, 1987?-
Sources:
1. Al -Kadi, "Origins of Cryptology", from Selections from Cryptologia (1998), pp. 93-123
2. Kahn, The Code Breakers : the story of secret writing (NY : 1967)
3. Badeau, The Genius of Arab Civilization : Source of the Renaissance (Cambridge : MIT, 1983)