Re: [PATCH 0/2] Add support for Qualcomm's PRNG

From: Stanimir Varbanov
Date: Fri Oct 04 2013 - 12:26:09 EST


Hi Ted,

On 10/03/2013 07:51 PM, Theodore Ts'o wrote:
> On Thu, Oct 03, 2013 at 05:52:33PM +0300, Stanimir Varbanov wrote:
>> This patch set adds hardware RNG driver wich is used to control the
>> Qualcomm's PRNG hardware block.
>> The first patch document the DT bindings needed to sucessfuly probe
>> the driver and the second patch adds the driver.
>
> Is this really a PRNG (pseudo-random number generator)? What are the
> guarantees which Qualcomm is providing for the PRNG? If it's really a
> PRNG such as AES(i++, NSA_KEY), then kudo to Qualcomm for being
> honest.
>
> If it is supposed to be (or at least claimed to be) a secure random
> number generator ala RDRAND suitable for use in cryptographic
> applications, calling it a PRNG is going to be a bit misleading.

I guess that it should follow NIST 800-90 recommendation, but I'm not
aware what DRBG mechanism is used.

To be honest I really don't know the hardware implementation details. I
put PRNG abbreviation in the cover letter just because I saw that
defines for register offsets are prefixed with PRNG_*. I could rename
all occurrences of PRNG to RNG. Is that will be enough to avoid confusions?

regadrs,
Stan
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