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

[Stanimir Varbanov]

Hi Ted, Peter,

On 10/09/2013 06:07 PM, H. Peter Anvin wrote:
> On 10/09/2013 07:46 AM, Stanimir Varbanov wrote:
>>
>> 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.
>>
> 
> There needs to be an architecturally guaranteed lower bound on the
> entropic content for this to be at all useful.  However, the hwrandom
> interface is currently expecting fully entropic output (which is almost
> certainly bogus... consider the PowerPC random number generator[1]) and
> so using it for a PRNG output is directly wrong.  This is part of why
> RDRAND support is implemented directly in rngd so that we can do the
> required cryptographic data reduction to produce fully entropic output.

I ran the rngtest with following command line:

# cat /dev/hw_random | rngtest -c 100000

Copyright (c) 2004 by Henrique de Moraes Holschuh
This is free software; see the source for copying conditions.  There is
NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.

rngtest: starting FIPS tests...
rngtest: bits received from input: 2000000032
rngtest: FIPS 140-2 successes: 99925
rngtest: FIPS 140-2 failures: 75
rngtest: FIPS 140-2(2001-10-10) Monobit: 10
rngtest: FIPS 140-2(2001-10-10) Poker: 9
rngtest: FIPS 140-2(2001-10-10) Runs: 20
rngtest: FIPS 140-2(2001-10-10) Long run: 38
rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
rngtest: input channel speed: (min=1.267; avg=53.222; max=2384.186)Mibits/s
rngtest: FIPS tests speed: (min=3.016; avg=48.847; max=49.931)Mibits/s
rngtest: Program run time: 75191914 microseconds

Could you guys comment those results?

regards,
Stan

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