Shihāb al-Dīn Abū 'l-Abbās Aḥmad ibn ‘Alī ibn Aḥmad ‘Abd Allāh al-Fazārī al-Shāfiʿī better known by the

epithet An epithet (, ), also byname, is a descriptive term (word or phrase) known for accompanying or occurring in place of a name and having entered common usage. It has various shades of meaning when applied to seemingly real or fictitious people, di ...

al-Qalqashandī ( ar, شهاب الدين أحمد بن علي بن أحمد القلقشندي; 1355 or 1356 – 1418), was a medieval Egyptian encyclopedist,

polymath A polymath ( el, πολυμαθής, , "having learned much"; la, homo universalis, "universal human") is an individual whose knowledge spans a substantial number of subjects, known to draw on complex bodies of knowledge to solve specific pro ...

and

mathematician A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change. History On ...

. A native of the

Nile Delta The Nile Delta ( ar, دلتا النيل, or simply , is the delta formed in Lower Egypt where the Nile River spreads out and drains into the Mediterranean Sea. It is one of the world's largest river deltas—from Alexandria in the west to ...

, he became a Scribe of the Scroll (''Katib al-Darj''), or clerk of the

Mamluk Mamluk ( ar, مملوك, mamlūk (singular), , ''mamālīk'' (plural), translated as "one who is owned", meaning " slave", also transliterated as ''Mameluke'', ''mamluq'', ''mamluke'', ''mameluk'', ''mameluke'', ''mamaluke'', or ''marmeluke'') ...

chancery in

Cairo Cairo ( ; ar, القاهرة, al-Qāhirah, ) is the capital of Egypt and its largest city, home to 10 million people. It is also part of the largest urban agglomeration in Africa, the Arab world and the Middle East: The Greater Cairo metr ...

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a List of transcontinental countries, transcontinental country spanning the North Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via a land bridg ...

. His magnum opus is the voluminous administrative encyclopedia ''Ṣubḥ al-Aʿshá''.

''Ṣubḥ al-aʿshā''

''Ṣubḥ al-Aʿshá fī Ṣināʿat al-Inshāʾ'' ('The Dawn of the Blind' or 'Daybreak for the Night-Blind regarding the Composition of Chancery Documents'); a fourteen-volume encyclopedia completed in 1412, is an administrative manual on geography, political history, natural history, zoology, mineralogy, cosmography, and time measurement. Based on the ''Masālik al-abṣār fī mamālik al-amṣar'' of

Shihab al-Umari Shihab al-Din Abu al-Abbas Ahmad ibn Fadlallah al-Umari ( ar, شهاب الدين أبو العبّاس أحمد بن فضل الله العمري, Shihāb al-Dīn Abū al-ʿAbbās Aḥmad ibn Faḍlallāh al-ʿUmarī), commonly known as Ibn Fadlal ...

, it has been called "one of the final expressions of the genre of

Arabic Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walter ...

administrative literature". Selections on "Seats of Government " and "Regulations of the Kingdom " from Early Islam to the Mamluks' have been published separately. The ''Ṣubḥ al-aʿshā'' was cited by David Kahn as the first published discussion of the substitution and transposition of ciphers, and the first description of a

polyalphabetic cipher A polyalphabetic cipher substitution, using multiple substitution alphabets. The Vigenère cipher is probably the best-known example of a polyalphabetic cipher, though it is a simplified special case. The Enigma machine is more complex but is st ...

, in which each

plaintext In cryptography, plaintext usually means unencrypted information pending input into cryptographic algorithms, usually encryption algorithms. This usually refers to data that is transmitted or stored unencrypted. Overview With the advent of comp ...

letter is assigned more than one substitution. The exposition on cryptanalysis included the use of tables of letter frequencies and sets of letters which cannot occur together in one word. Kahn therefore cited it as the first work in human history that described cryptology, because it described both cryptography and cryptanalysis. Al-Qalqashandi quoted the text relevant to cryptology from the work of Ibn al-Durayhim (1312–1361) that was once considered lost. Later discoveries in Istanbul‟s Sulaimaniyyah Ottoman Archives did not just find the work by Ibn Duraihim, but also works of al-Kindi in the 9th century that is now considered the oldest work on cryptology.Kathryn A. Schwartz (2009): Charting Arabic Cryptology's Evolution∗, ''Cryptologia'',33:4, 297-304

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''Ṣubḥ al-aʿshā''

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