Ibn 'Adlan


ʻAlī ibn ʻAdlān, 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.
Ibn 'Adlan was educated in Baghdad and lived in Damascus and Cairo.

Cryptanalysis

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".