ʻAlī ibn ʻAdlān (Arabic: علي بن عدلان; 1187–1268 CE), born in Mosul, was an Arab cryptologist, linguist and poet who is best known for his early contributions to cryptanalysis, to which he dedicated more than one book. He was also involved in literature and poetry.
His two major works on cryptanalysis were Al-mu'lam and Al-mu'allaf lil-malik al-'Asraf. One of his most important contributions was on sample size for use of frequency analysis. He believed that a cryptogram "should be at least 90 letters long and that each of the 28 letters of Arabic should be represented at least three times".
- Deavours, Cipher A. (1997). Selections from Cryptologia: History, People, and Technology. Artech House. p. 116. ISBN 9780890068625.
- Series on Arabic Origins of Cryptology (Series Eds. M. Mrayati, Y. Meer Alam and M. H. at_Tayyan), published by King Faisal Center for Research and Islamic Studies (KFCRIS) & King Abdulaziz City for Science and Technology (KACST), Riyadh. Vol. 2, ibn `Adlān's Treatise al-mu'allaf lil-malik al-'Ašraf, ISBN 9960-890-18-X, 2004, 113 pp., 17 × 24 cm, softcover.
- Broemeling, Lyle D. (1 November 2011). "An Account of Early Statistical Inference in Arab Cryptology". The American Statistician. 65 (4): 255–257. doi:10.1198/tas.2011.10191.