Abstract: A random number generator comprises a laser for generating photons, an assembly of neutral density filters to attenuate the photons to an average of number of photons detected and to detect the average number of photons during each interval in a series of like time intervals, a photomultiplier tube to detect the occurrence of a fraction of the attenuated photons during a set length of time, and a clock and shift register to record a first value for detection of any photons during a selected single time interval in the series of time intervals, and to record a second value for detection of less than the average number of photons during the selected single time interval. The values recorded in the shift register for the series of time intervals are a string of truly random numbers.