RANDOM NUMBER GENERATION FROM SRAM CELLS

Methods are provided for generating a random bit-string from an array of SRAM cells. Such a method includes reading the start-up value of each cell over multiple power-ups of the array, and calculating, from the multiple start-up values of each cell, a bias value indicative of entropy of that cell. The method also includes generating, based on the bias values, an address list in which addresses of cells in the array are listed in order of entropy of the cells. This address list is stored in non-volatile memory. The method further comprises, on a subsequent power-up of the array, generating a random bit-string by reading the start-up values of a set of cells selected in decreasing entropy order of the address list. Hardware random number generators exploiting such methods are also provided.