Obtaining true-random binary numbers from a weak radioactive source

In this paper, we present a physical random number generator (RNG) for cryptographic applications. The generator is based on alpha decay of Americium 241 that is often found in common household smoke detectors. A simple and low-cost implementation is shown to detect the decay events of a radioactive source. Furthermore, a speed-optimized random bit extraction method was chosen to gain a reasonable high data rate from a moderate radiation source (0.1 mu Ci). A first evaluation by applying common suits for analysis of statistical properties indicates a high quality of the data delivered by the device.