Wide Band Physics Entropy Source For High Speed Random Number Generator

The random number has widespread application in telemetering remote control, digital communication and cryptology. At present, there are many kinds of physical random phenomena can work as the entropy source of the real random number generator, and which have been certificated and productions. However, limited by the mechanism of extracting bit sequences, the rate of this kind of generators has been only of tens of mega-hertz per second, which is far slower than the data rates of fiber communications. Therefore, we need to seek for a new random phenomenon for the physical entropy source of the random number generator. Luckily, the semiconductor laser with optical feedback or optical pour can produce several GHz to several dozens GHz band width chaos laser, which guaranteed the high rate random number. Therefore, the chaos laser works as the physical entropy source of the real random number generator have been the hot spot of this domain research.This article produces the chaos laser based on the optical feedback semiconductor laser, under experiment and the off-line processing, studied the different processing methods of the chaos laser, which can eliminated the weak periodicity caused by the feedback cavity, and turn into the physical entropy source of the real random number generator. The main works are summarized as follows:1. We summarize the physical entropy source of the real random number generator. The basic principles and characteristic of the chaos produced by the semiconductor laser with optical feedback are introduced, and the feasibility of works as the physical entropy source is analyzed.2. The influence of external cavity length to the randomness is experimentally studied. The results indicate that the generated random sequence has an weak periodicity caused by the external cavity feedback under single-channel chaotic source, and can not pass all tests of the NIST. On the other hand, the weak periodicity can be eliminated using two different chaotic sources with their external cavity length are not proportional with each other to XOR processing. We realized a 500 Mbit/s random number generator, the obtained random sequence can pass all tests of the NIST.3. The exclusive-or operation on corresponding random bits in samples of the chaotic signal and its time-delay signal from a same single chaotic laser is experimentally studied. An empirical criterion is found through a large number of experiments:when the correlation coefficient is less than 0.007, the corresponding delay time of autocorrelation trace is considered as the delay time between the chaotic signal and its time-delay signal, corresponding to the delay line length, the random number sequence can be generated with verified randomness. Make use of this criterion, a random number generator at a rate of 1Gbit/s is achieved.