There is proposed a method of managing an array of keys by a device, each key pressed short-circuiting a row and a column of the array. During at least part of a time slot lying between two successive iterations of a sweep phase, the device performs a first protection mechanism, including reading a logic value on at least one row or column, and detecting an attempted illicit sweep as a function of the logic value read, and/or a second protection mechanism, including writing an arbitrary logic value, equal to or different from the predetermined logic value, on at least one row or column, so as to prevent an attempted illicit sweep.