Correlation-based cryptanalysis of a ring oscillator based random number generator

Random Number Generators (RNGs) are crucial for many security applications for generating unpredictable bit streams. Fully digital Random Number Generators which are implemented in FPGA platforms are usually preferred for their high-speed availability and their ease of integration to digital platforms. On the other hand, attention should be paid while placing and routing ring oscillators as much as possible. This paper presents an implementation of a Random Number Generator based on ring oscillators on FPGA and the cryptanalysis of it via correlation analysis. The main aim of this paper is to analyze the correlation between the output bit streams produced by the RNG and the attack circuit coupled to the main circuit. In the main RNG circuit, all ring oscillators are placed far from each other to obtain independent random bit streams at the output. Experimental results show that the effective correlation between RNG and attack circuit can be obtained due to coupling.