On 10/31/2012 12:29 AM, Paolo Bonzini wrote:
Related to this, rdrand's "entropy content" in the worst case will be
only 1/255th of the data it produces: Intel documents that one 256-bit
seed will result in up to 1022 64-bit random numbers. Yet, it is good
enough to drive rngd. Would it make sense for QEMU to implement the
same kind of stretching of /dev/random data, to avoid depleting the
host's entropy pool too fast?
Absolutely not; in fact, we have to do data reduction in rngd for
exactly this reason (and a Qemu backend would have to do the same).
There is a new RDSEED instruction in newer CPUs to correct this.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
