Abstract: This method is implemented within a digital processor by: a) searching an internal register (R1, R2, R3, ... R(n)) of the processor which content (b0, b1, b2, ... b(n)) changes over time; b) extracting at a given time n bits from the register, n ? 1; c) using the n bits extracted at step b) as bit(s) for forming a random number of N bits to be generated; d) reiterating (250) steps a) to c) until obtaining the N bits of the random number; and e) providing the random number to an application circuit or software. In order to increase randomness, the method further comprises a selection (240), by a random of pseudo-random process, of the n bits of the register which will be extracted, and/or a selection (230), by a random of pseudo-random process, of one register among a plurality of internal registers (R1, R2, R3, ...