Entropy transfers in the Linux Random Number Generator

Abstract: One of the services provided by the operating system to the applications is random number generation. For security reasons, the Linux Random Number Generator is built upon the combination of a deterministic algorithm known as the cryptographic post-processing and an unpredictable physical phenomenon called an Entropy Source. While the various cryptographic post-processing algorithms and their properties are well described in the literature, the entropy collection process itself is little studied. This report first presents the different approaches to random number generation, and then details the architecture of the Linux Random Number Generator. Then, we present the experiments we performed to monitor entropy transfers. Our results show that the main source of randomness in the system is the behavior of the hard drive, and that most random numbers produced by the generator are actually consumed by the kernel itself. Key-words: random number generation, operating systems, linux, entropy Entropy transfers in the Linux Random Number Generator Résumé: La génération de nombres aléatoires est l’un des services offerts par le système d’exploitation aux applications qu’il exécute. Pour des raisons de sécurité, le générateur d