The e2random Entropy Harvester and PRNG for Linux

Many efficient methods of generating “good” random numbers exist in the literature of mathematics and computer science. One particular method of generating usable randomness is with “extractors”: graphs which will transform “bad” randomness (i.e. a smaller ratio of entropy/data, or randomness distributed poorly) to “good” randomness (of a provable level of security) by an additional input of only a small number of truly random bits. The current {,u}random PRNG for Linux is not extensible, which prompted work on a new erandom PRNG using these extractors. The work on erandom led to a number of improvements to the entropy harvesting methods used by the Linux kernel, as {,u}random and the entropy harvester are inseperable. The new entropy harvester eh2, combined with the erandom PRNG make up the new pseudorandom number generation subsystem, called e2random. This new driver offers greater flexibility and extensibility than the original {,u}random.