The invention relates to a method for generating random numbers in which oscillating digital output signals (A1, A2, . . . , AL) of unequal or equal periodicity are generated by at least two ring oscillators (32, 33, 34), an external parity
signal (PS) representing a logical state (“0,”“1”) being generated when an odd number of the output signals (A1, A2, . . . , AL) take on a specified logical state (“1”). According to the invention, the external parity
signal (PS) is fed back to an external parity input (36, 37, 38) of each of the respective ring oscillators (32, 33, 34). The invention further relates to a random
number generator having at least two ring oscillators (32, 33, 34), made up in particular of independently free-running
inverter chains with feedback having an odd number (K) of series-connected inverters (inv1,2, inv2,1, inv3,1, . . . , invi,j, . . . , invL,KL) that generate oscillating digital output signals (A1, A2, . . . , AL) of unequal or equal periodicity, and having first parity
signal generating means (XOR) that generate an external parity signal (PS) representing a logical state (“0,”“1”) when an odd number of the output signals (A1, A2, . . . , AL) take on a specified logical state (“1”). According to the invention, there are feedback means (xor1, xor2, xor3, xor4, . . . , xorL) that feed back the external parity signal (PS) to an external parity input (36, 37, 38) of each of the respective ring oscillators (32, 33, 34). In this invention the cooperation of
chaotic dynamics (feedback of the parity signal) and true randomness (
jitter due to thermal
noise) in digital circuits, a novel theoretical principle for generating random numbers, has been made into an efficient practical solution.