A new technique for ultrafast physical random number generation using optical chaos

In this paper, we numerically demonstrate a new extraction scheme for generating ultra-fast physically random sequence of bits. For this purpose, we utilize a dual-channel optical chaos source with suppressed time delayed (TD) signature in both the intensity and the phase of its two channels. The proposed technique uses M 1-bit analog-to-digital converters (ADCs) to compare the level of the chaotic intensity signal at time t with its levels after incommensurable delay-interval T^m, where m = {1,2, ..., M}. The binary output of each 1-bit ADC is then sampled by a positive-edge-triggered D flip flop. The clock sequence applied to the flip-flops is relatively delayed such that the rising edge of the clock triggering the m flip-flop precedes the rising edge of the clock of a subsequent m+1 flip-flop by a fixed period. The outputs of all flip flops are then combined by means of a parity-check logic. Numerical simulations are carried out using values of parameters at which TD signature is suppressed for chosen values of setup parameters. The 15 statistical tests in Special Publication 800-22 from NIST are applied to the generated random bits in order to examine the randomness quality of these bits for different values of M. The results show that all tests are passed from M = 1 to M = 39 at sampling rate up to 34.5 GHz which indicates that the maximum generation rate of random bits is 2.691 Tb/sec using a chaotic source of single VCSEL and without employing any pre-processing techniques.