High-speed physical random number generation using a chaotic semiconductor laser

Abstract

A high-speed physical random number generator based on a chaotic laser was proposed and experimentally demonstrated. The broadband chaotic laser generated by an external cavity laser diode was employed as the physical entropy source. The chaotic signal was sampled and converted by an 1-bit analog-to-digital converter to a binary sequence with the rate of up to 1 Gb/s. To overcome the periodicity in random sequence due to the photo round trip time in the external cavity, the exclusive-or (XOR) operation on corresponding random bits in samples of the chaotic signal and its time-delay signal from a same single chaotic laser was executed. The scheme was simpler than the present random number generator in which random number sequences were obtained real-timely by doing XOR operation on the binary sequences from two chaotic semiconductor lasers. In addition, the proper selection of delay length was analyzed. A large number experiments show that when the corresponding delay time of autocorrelation trace with correlation coefficient of less than 0.007 is considered as the delay time between the chaotic signal and its time-delay signal, streams of random numbers can be generated with verified randomness.