2016-05-27 17:38:07

by Sandy Harris

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Subject: Could this be applied to random(4)?

A theoretical paper on getting provably excellent randomness from two
relatively weak input sources.
https://www.sciencenews.org/article/new-technique-produces-real-randomness


2016-05-27 18:30:54

by Stephan Müller

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Subject: Re: Could this be applied to random(4)?

Am Freitag, 27. Mai 2016, 13:38:05 schrieb Sandy Harris:

Hi Sandy,

> A theoretical paper on getting provably excellent randomness from two
> relatively weak input sources.
> https://www.sciencenews.org/article/new-technique-produces-real-randomness

This document describes extractors. Those extractors are intended to combine
*independent* sources with weak entropy.

None of our sources we have in add_*_randomness are independent.

In addition, I am not sure why this research is so hyped. I think that the 3-
source extractor described in [1] is more efficient and easier to implement

[1] "Extracting Randomness Using Few Independent Sources" by Boaz Barak,
Russell Impagliazzo, Avi Wigderson

Ciao
Stephan

2016-05-27 20:17:13

by Sandy Harris

[permalink] [raw]
Subject: Re: Could this be applied to random(4)?

On Fri, May 27, 2016 at 2:30 PM, Stephan Mueller <[email protected]> wrote:

> This document describes extractors. Those extractors are intended to combine
> *independent* sources with weak entropy.
>
> None of our sources we have in add_*_randomness are independent.

No, but it would be easy to get two independent sources, interrupts
and some sort of timer jitter thing as in my maxwell, your jitter
driver, havege, ...

2016-05-29 19:20:13

by Stephan Müller

[permalink] [raw]
Subject: Re: Could this be applied to random(4)?

Am Freitag, 27. Mai 2016, 16:09:53 schrieb Sandy Harris:

Hi Sandy,

> On Fri, May 27, 2016 at 2:30 PM, Stephan Mueller <[email protected]>
wrote:
> > This document describes extractors. Those extractors are intended to
> > combine *independent* sources with weak entropy.
> >
> > None of our sources we have in add_*_randomness are independent.
>
> No, but it would be easy to get two independent sources, interrupts
> and some sort of timer jitter thing as in my maxwell, your jitter
> driver, havege, ...

I think I would concur with you here. From my LRNG code:

static int lrng_pdrbg_seed_internal(u8 *outbuf, u32 outbuflen, bool
fullentropy,
bool drain)
{
...
/*
* Concatenate the output of the noise sources. This would be the
* spot to add an entropy extractor logic if desired.
...

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Ciao
Stephan