If I understand the source code correctly[1] they use the output of rdrand directly. However they also have an option "hw.ivy_rng_enable"[2] to disable it. The

If I understand the source code correctly[1] they use the output of rdrand directly. However they also have an option "hw.ivy_rng_enable"[2] to disable it. The code is actually nicer to read than the Linux counterpart and it seems trivial to implement a new "random_adaptor" that would xor the output of ivy (rdrand) with yarrow (the software one). [1] http://fxr.watson.org/fxr/source/dev/random/ivy.c http://fxr.watson.org/fxr/source/dev/random/ivy.c [2] http://fxr.watson.org/fxr/source/dev/random/probe.c http://fxr.watson.org/fxr/source/dev/random/probe.c