A Study of Entropy Sources in Cloud Computers: Random Number Generation on Cloud Hosts

Cloud computing hosts require a good source of cryptographically strong random numbers. Most of the standard security practices are based on assumptions that hold true for physical machines, but don’t translate immediately into the domain of virtualized machines. It is imperative to reconsider the well accepted security practices that were built around physical machines, and whether blind application of such practices results in the possibility of a data breach, machine control, or other vulnerabilities. Because of Cloud computers reliance on virtualization, access to the hardware based random number generator is restricted, and virtualization can have unforeseen effects on the operating system based random number generator. In this paper, the entropy pool poisoning attack is introduced and studied and a Cloud Entropy Management System is proposed. Extensive experimental study verified that there are measurable problems with entropy in Cloud instances, and the management system effectively solves them.