Al-Kindi, Cryptography, Code Breaking and Ciphers
Much of the content of this article is based on the book by Simon Singh(1), the author has devoted a section to the Muslim contribution to the subject. A special emphasis is made on the Famous Muslim Philosopher and Mathematician Al-Kindi as the originator of the first method of code breaking.
Throughout history the need for secrecy has been important. Governments and ordinary people have increasingly sought to secure the delivery of certain messages and important information in a way that allows only the intended recipient access and comprehension. This need for secrecy brought about the invention and the art of concealment, coding and code making. In return the need for intelligence and information lead to the development of code breaking techniques. These techniques primarily attack a particular weakness that a code or concealment method may have, rendering the sought after information apparent and comprehensible to the assailant..(1)
Evidence of concealing messages can be seen throughout history. These examples in many cases have had considerable effects on the outcome of history, as they may have decided the outcome of battles or the rise or fall of a king or Queen.
Simply hiding a message or "Steganography" can be an effective method by which a message may be delivered without being detected or intercepted by the "enemy". The effectiveness of Steganography is however dependant on the elaborate way in which the message has been concealed, and on the efficiency of enemy intelligence and their persistence in searching and investigating the courier or delivery medium.
In the fifth century A.C. a Greek exile named Demaratus living in the Persian Empire witnessed the build up and mass of forces by the Persian king Xerxes. Xerxes had intended on conquering the Greeks and Spartans, and was massing his great fleet and forces in preparation for a surprise attack that would catch the Greeks off guard leading to a simple victory. Feelings of patriotism lead Demaratus to warn the Spartans, a task which was not easy as he was leaving within the Persian empire, and so any form of correspondence between him and the Greeks may be intercepted leading to his execution. He therefore demonstrated ingenuity by stripping a writing tablet of its wax coating, writing on the wood underneath, and then re-waxing the tablets. The tablets passed any Persian guards and check points as they were seen to be "Blank", when they reached Sparta a clever princess worked out the riddle and told them to remove the wax, there underneath lay the message from Demaratus. The Greeks then took action and managed to mobilise and prepare troops in anticipation for the Persian invasion, the subsequent battle was lost by the Persians as they had lost the element of surprise. Their fleet fell into an ambush prepared by the Greeks.(1)
Although Steganography may have been a sufficient method of concealing message in many cases, its success or failure depends on the message not being discovered. Had the Persian guards removed the wax off the apparently blank tablets the outcome of Xerxes battle with the Greeks would have been different. Due to this obvious weakness in Steganography the invention of Cryptography became imminent.
Cryptography is a method or technique by which a message may be altered so that it becomes meaningless to anyone else but the intended recipient. This is done primarily in two basic ways, one is to change the position of letters or words within a message, the other is by substituting letters or words by different ones, "Transposition" and "Substitution" respectively.(1)
For transposition to be effective and secure, letters rather than words need to be rearranged, this effectively scrambles the message and produces an "Anagram". Transposition could be done for example by writing the order of letters in a word backwards, so that word becomes drow. It is more effective to rearrange the letters in whole sentences or the whole message rather than single words.
If transposition was not limited to words or a certain order the number of different possibilities for rearranging a thirty five letter message rises to 50,000,000,000,000,000,000,000,000,000,000 different distinct rearrangements making the task of working out the correct rearrangement impossible even if all the people on earth were to check a single rearrangement every minute.(1)
Transposition can thus yield a high level of security; nevertheless it can produce an increasingly difficult anagram which may become so complicated that even the intended recipient would not be able to decode it. Therefore transposition needs to follow a simple and straight forward system agreed upon by sender and recipient beforehand.
Substitution is the other method by the meaning of a message may be concealed. This method can follow two routes either by substituting words for other "Code" words, or by substituting letters within the message by other letters or symbols. Substitution can be simplified by deciding on a specific "Key", the key is what defines a specific method of substitution, combined with an "Algorithm" which specifies the letters or symbols which are used in the substitution in a specific order. When combined and applied to plain text the key and algorithm is what generates the "Cipher". Working with the plain English alphabet, allowing the algorithm to be any arrangement of the different letter, it is possible to generate more 400,000,000,000,000,000,000,000,000 different distinct rearrangements of letters and so the same number of different ciphers, thus producing a high level of security, baring in mind that the recipient need only to keep the key safe.(1)
Using the simple substitution method of cryptography, important messages and sensitive information were kept from the prying eyes of enemies for centuries. Any attempt of breaking such encrypted messages was futile, and only lead to sleepless nights and no results, some people even started thinking that such encrypted messages were divine, until the 9th Century AC when a Muslim scholar in Baghdad changed the face of Cryptography for ever.(1, 2, 5, 6)
During the Abbasid rule, the lavished economic condition of the country allowed people to peruse reading, learning and research in all disciplines. People were encouraged to learn; books were manually copied and sold in numerous libraries and bookshop. The works of the Greeks, Persians and others were translated and made available to every household. Islamic teachings also make it obligatory for all Muslims to peruse and acquire knowledge of all the sciences with similar and equal degree.(1, 2, 3)
Through these conditions, the critical conditions needed for the birth of "Cryptanalysis" or deciphering an encrypted message were realised. This was first done by the Muslim scholar named Al-Kindi.(1, 2)
Abu Yusuf Ya'qub ibn Ishaq Al-Kindi better known to the west as Alkindous, was an ethnic Arab descending from the royal Kindah tribe, which originated in southern Arabia and had almost mythical routes such as Qayss.(5,
by: Tariq Al-Tayeb, B.Sc, M.Sc. (FSTC Limited) by: Professor Salim Al-Hassani
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