Limitations on SP 800-90C External Conditioners and How to Overcome Them (N20b)
It is conservative to use all available high-quality sources of entropy to seed security-relevant DRBGs, irrespective of their validation statuses. One reasonable-sounding approach to accomplish this goal is to use an SP 800-90C external conditioning step, but such external conditioners can only integrate information from validated entropy sources. This results in implementation changes when moving a module across different OEs when the validation status of the available entropy sources varies, and in some systems may prevent integration of entropy from non-validated entropy sources.
The speakers demonstrate how to use an RBGC construction to accomplish this same goal in a compliant fashion.