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Re: x86 CPU RNG support, take 2



On 02 Jan, 2016, at 12:01 EST, Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost> wrote:
>   Date: Fri, 1 Jan 2016 14:37:53 -0500
>   From: Thor Lancelot Simon <tls%panix.com@localhost>
>   If I do that, we'll get a cpurng entropy source even on CPUs that don't
>   actually have one.  I'd rather not.
> 
> In that case, why not make cpu_rng_init tell the caller whether or not
> there is a CPU RNG?  It seems to me the CPU feature bits should
> determine the presence of the rndsource, not the dynamic behaviour of
> the hardware itself.

I can't pretend to have been following this terribly close, but isn't "a CPU that claims to have a cpurng entropy source but is lying" kind of a threat model here? (Ala Juniper's recent hoopla.)

--
Gabriel Rosenkoetter
gr%eclipsed.net@localhost

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