Re: [PATCH] CPU Jitter RNG: inclusion into kernel crypto API and /dev/random

From: Stephan Mueller
Date: Wed Nov 06 2013 - 06:43:21 EST


Am Dienstag, 5. November 2013, 14:45:58 schrieb Stephan Mueller:

Hi Pavel,

>Am Dienstag, 5. November 2013, 13:25:40 schrieb Stephan Mueller:
>
>Hi Pavel,
>
>>Am Montag, 4. November 2013, 00:32:07 schrieb Pavel Machek:
>>>But they usually _do_ have RTC or other clock, not driven by CPU
>>>oscilator. Good.
>>>
>>>What about just
>>>
>>>while (!enough_entropy) {
>>>
>>> cur_time = read_rtc();
>>> simulated_tsc = 0;
>>> while (cur_time == read_rtc())
>>>
>>> simulated_tsc++;
>>>
>>> gain_entropy_from(simulated_tsc)
>>>
>>>}
>>
>>That is an interesting piece of code -- what would you do in the
>>gain_entropy_from function?
>
>Please disregard my question.
>
>I plugged that idea into my current Jitter RNG processing and disabled
>the other jitter measurements to get a clear, isolated picture.
>
>The result is also a white noise! And it is even quite fast.

After doing some more research on this approach, I have to admit that
the output not good (i.e. white noise) in all situations. Therefore, I
dropped that (for now).

But thank you very much for your suggestion.

Ciao
Stephan
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