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

From: Stanimir Varbanov
Date: Wed Oct 09 2013 - 10:48:00 EST


Hi Ted,

On 10/04/2013 09:10 PM, Theodore Ts'o wrote:
> On Fri, Oct 04, 2013 at 07:23:50PM +0300, Stanimir Varbanov wrote:
>> 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?
>
> If that's what the Qualcomm documentation uses, maybe we should stick
> with it, and add some explanatory comments. Is there any
> documentation for this block that is public that you can either send
> me a a pointer to?

No, there is no public documentation for the block. Here is the driver
documentation which I used as a base [1].

My guess was that - if it is PRNG (got from hardware description link
above) than according to wiki [2] it is also known as a deterministic
random bit generator (DRBG). The recommendation for RNG using DRBG is
NIST 800-90.

Of course I could be wrong, so I can add a comment that this is just a
guess and we shouldn't over-reliance on this.

regards,
Stan

[1]
https://www.codeaurora.org/cgit/quic/la/kernel/msm/tree/Documentation/arm/msm/msm_rng-driver.txt?h=jb_3.2.1

[2] http://en.wikipedia.org/wiki/Pseudorandom_number_generator
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