A random number generator comprising an oscillator with an output signal dependant upon a random source, a sampling device to sample the output signal from the oscillator to obtain a sampled oscillator output, and a fixed frequency clock driven linear feedback shift register (LFSR) communicatively coupled to the sampling device via a digital gate to receive the sampled oscillator output, and to provide a random number at an output of the LFSR. Additionally, the random number generator may comprise an optional mixing function communicatively coupled to the LFSR to read the random number, and to insert the random number into an algorithm to obtain a robust random number.