The CPU Jitter Random Number Generator provides a non-physical true random number generator that works equally in kernel and user land. The only prerequisite is the availability of a high-resolution timer that is available in modern CPUs.
A PDF documentation is also available. The pictures and graphs are better to read in the PDF version.
The following source code contains the implementation of the CPU Random Number Generator.
Small enhancement of Kernel DRNG support -- making the reseeding and rekeying implementation more robust for edge conditions
Compile the CPU Jitter RNG as stand-alone shared library
Addition of OpenSSL engine support
The test cases without the results that went into the documentation can be found in the test tarball. Start with the scripts getstat.sh. If you are interested in the test results, the SVG files, etc., please let me know as this is a 1GB archive.