True random number generation in block memories of reconfigurable devices

We present concepts and implementations to transform write collisions in memory blocks into an entropy source for random number generation. Write collisions in dual-ported block memories occur when both memory ports write simultaneously different data at the same memory location. After a thorough analysis of this effect, we present a robust methodology to generate digitized noise and randomness from such write collisions and also provide details how to implement post-processing methods for efficient bias and correlation removal. Finally, we present three concepts and implementations for random number generators stages that can deliver random data at an output rate of more than 100 MBit/s.