Hardware Random Number Generator - Early Work

Early Work

One early way of producing random numbers was by a variation of the same machines used to play keno or select lottery numbers. Basically, these mixed numbered ping-pong balls with blown air, perhaps combined with mechanical agitation, and use some method to withdraw balls from the mixing chamber (U.S. Patent 4,786,056). This method gives reasonable results in some senses, but the random numbers generated by this means are expensive. The method is inherently slow, and is unusable in most automated situations (i.e., with computers).

On 29 April 1947 RAND Corporation began generating random digits with an "electronic roulette wheel", consisting of a random frequency pulse source of about 100,000 pulses per second gated once per second with a constant frequency pulse and fed into a five-bit binary counter. Douglas Aircraft built the equipment, implementing Cecil Hasting’s suggestion (RAND P-113) for a noise source (most likely the well known behavior of the 6D4 miniature gas thyratron tube, when placed in a magnetic field). Twenty of the 32 possible counter values were mapped onto the 10 decimal digits and the other 12 counter values were discarded.

The results of a long run from the RAND machine, carefully filtered and tested, were converted into a table, which was published in 1955 in the book A Million Random Digits with 100,000 Normal Deviates. The RAND table was a significant breakthrough in delivering random numbers because such a large and carefully prepared table had never before been available. It has been a useful source for simulations, modeling, and even for deriving the arbitrary constants in cryptographic algorithms to demonstrate that the constants had not been selected for (in B. Schneier’s words) "nefarious purpose(es)." Khufu and Khafre do this, for example. See: Nothing up my sleeve numbers.

The RAND book is still in print, and remains an important source of random numbers.

A Million Random Digits with 100,000 Normal Deviates

This 1955 book was a product of RAND’s computing power (and patience). The tables of random numbers in the book have become a standard reference in engineering and econometrics textbooks and have been widely used in gaming and simulations that employ Monte Carlo trials. Still the largest known source of random digits and normal deviates, the work is routinely used by statisticians, physicists, polltakers, market analysts, lottery administrators, and quality control engineers. — Rand Corporation