Abstract: The invention concerns a random number generator comprising a n-bit LSFR at least one oscillator having at least one delay element introducing a variable delay in the counter feedback loop, and at least one sampling/holding device having at least one input coupled to an output of the oscillator, and at least one output coupled to a input of the LSFR, and a clock input receiving a sampling clock signal at a much lower frequency than the oscillator frequency. Said generator is for example configured to vary the delay introduced by the oscillator delay based on a number q of feedback bits among the n bits of the LSFR output, where q is a an integer such that 1?q?n.