Jitter RNG provides a noise source using the CPU

 execution timing jitter. It does not depend on any system resource
 other than a high-resolution time stamp. It is a small-scale, yet
 fast entropy source that is viable in almost all environments and
 on a lot of CPU architectures.
 .
 The implementation of the Jitter RNG is independent of any operating
 system. As such, it could even run on baremetal without any operating
 system.
 .
 The design of the RNG is given in the documentation found in at
 http://www.chronox.de/jent . This documentation also covers the full
 assessment of the SP800-90B compliance as well as all required test
 code.