The article explores evidence for Babylonian scholars working for Ashurbanipal’s library. The colophons of Ashurbanipal’s library tablets are usually highly standardized and, as opposed to the colophons of private or temple libraries, do not contain any information about copyists. The colophons on Babylonian tablets found at Nineveh normally are very short and provide only theinformation about the original tablet. The colophons of the two scions of the prominent family of lamentation priests, descendants of Šumu-libši, the lamentation priest of Mardukat Esagil, contain their names written cryptographically. The article suggests the decipherment of this cryptography. Analysing this cryptography and juxtaposing it with the other Šumu-libši-related colophons on the tablets found in Assyria sheds light on the input of Babylonian scholars in creating the library of Ashurbanipal.