From: "Ard Biesheuvel" <ardb@kernel.org>
To: devel@edk2.groups.io, Rebecca Cran <rebecca@nuviainc.com>
Cc: Sami Mujawar <Sami.Mujawar@arm.com>,
Samer El-Haj-Mahmoud <Samer.El-Haj-Mahmoud@arm.com>,
Ard Biesheuvel <Ard.Biesheuvel@arm.com>,
"leif@nuviainc.com" <leif@nuviainc.com>,
"rfc@edk2.groups.io" <rfc@edk2.groups.io>,
Jiewen Yao <jiewen.yao@intel.com>,
Rahul Kumar <rahul1.kumar@intel.com>, nd <nd@arm.com>,
Jose Marinho <Jose.Marinho@arm.com>
Subject: Re: [edk2-devel] RFC: Adding support for ARM (RNDR etc.) to RngDxe
Date: Thu, 11 Feb 2021 19:26:25 +0100 [thread overview]
Message-ID: <CAMj1kXFK=uFtF_F8S7PhWn_TQJzFm2HMC4Ns5Uh4vOFLtmQzrw@mail.gmail.com> (raw)
In-Reply-To: <dd307ec4-4b5f-4e98-aa32-3a145971548e@nuviainc.com>
On Wed, 10 Feb 2021 at 23:49, Rebecca Cran <rebecca@nuviainc.com> wrote:
>
> On 1/15/21 7:51 PM, Sami Mujawar wrote:
>
> > I have shared some initial thoughts on the RNG implementation updates at https://edk2.groups.io/g/devel/files/Designs/2021/0116/EDKII%20-%20Proposed%20update%20to%20RNG%20implementation.pdf
> >
> > Kindly let me know your feedback or if you have any queries.
> The ARMv8.5 RNDRRS instruction appears to be missing from the diagram on
> page 11 - it has RngLib|RNDR, which is listed under PRNG, but RNDRRS
> returns a true random number. From the Arm ARM:
>
> "Returns a 64-bit random number which is reseeded from the True
> Random Number source immediately before the read of the random number."
>
This is an unfortunate oversight in the architecture, but RNDRRS most
certainly does not return a true random number.
RNDR and RNDRRS both return the output of a DRBG (pseudo RNG), and the
only difference is the reseed rate: RNDRRS triggers a reseed on every
invocation, whereas RNDR triggers a reseed at an IMPDEF rate.
next prev parent reply other threads:[~2021-02-11 18:26 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-09 4:32 RFC: Adding support for ARM (RNDR etc.) to RngDxe Rebecca Cran
2020-12-09 4:47 ` [edk2-devel] " Samer El-Haj-Mahmoud
2020-12-10 11:26 ` Sami Mujawar
2020-12-10 12:52 ` Leif Lindholm
2020-12-10 13:43 ` [edk2-rfc] " Yao, Jiewen
2021-01-14 21:05 ` Rebecca Cran
2021-01-16 2:51 ` Sami Mujawar
2021-02-10 22:49 ` Rebecca Cran
2021-02-11 18:26 ` Ard Biesheuvel [this message]
2021-04-20 20:04 ` Rebecca Cran
2021-04-22 9:30 ` Sami Mujawar
2021-04-26 14:45 ` Rebecca Cran
2021-04-26 21:28 ` Rebecca Cran
2021-04-26 21:45 ` [EXTERNAL] " Bret Barkelew
2021-04-27 13:22 ` Sami Mujawar
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