Abstract: Data, such as usage restriction data (3), are stored in a memory (2) of an electronic device (1). When new data (3) is determined, a number of previously stored random data files (4) are transferred to a secure execution environment (7), in which a number of further random data files and a random seed are generated. A series for selecting some previously stored data files and some further data files is created, and a checksum over the selected files is calculated. The random seed is stored with the data, and an authentication code thereof is calculated using the checksum. The updated data and the generated further data files are returned from said secure execution environment (7), and the further data files replace a corresponding number of the previously stored data files according to the created series. The updated data is stored in the memory (2).