Re: [PATCH] eal: add support for TRNG with Arm RNG feature

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri, 26 Jul 2024 18:34:44 +0000
Shunzhi Wen <Shunzhi.Wen@arm.com> wrote:

> > I'm missing a rationale here. Why is this useful?
> >  
> This creates an API for HW that supports cryptographically secure random number generation.
> 
> > If you want to extend <rte_random.h> with a cryptographically secure
> > random number generator, that's fine.
> >
> > To have an API that's only available on certain ARM CPUs is not.
> >
> > NAK
> >  
> The primary goal of this patch is to provide a direct interface to HW,
> instead of letting kernel handle it. This is not an API just for Arm
> CPUs, as other vendors also have similar HW features. For instance,
> Intel and AMD has support for x86 RDRAND and RDSEED instructions, thus
> can easily implement this API.
> 
> > A new function should be called something with "secure", rather than "true"
> > (which is a bit silly, since we might well live in a completely deterministic
> > universe). "secure" would more clearly communicate the intent, and also
> > doesn't imply any particular implementation.
> >  
> Regarding the terminology, “cryptographically secure random number”
> is a more accurate and meaningful term than “true random number.”
> This change will be made in the description, and the function name will
> be replaced with rte_csrand.

If you decide to rte_csrand() it should fallback to get_random or get_entropy.

Note: many people don't fully trust RDRAND or ARM CPU instructions. 
That is why the Linux entropy calls do not use only the HW instructions.