Re: [PATCH v3 00/03]: hwrng: an in-kernel rngd

From: H. Peter Anvin
Date: Mon Apr 14 2014 - 12:10:29 EST


I think the default should be zero, so each hwrng driver maintainer would have to consider what guarantees that particular driver can give. If anything 50% ought to be the maximum.

On April 14, 2014 9:02:11 AM PDT, Torsten Duwe <duwe@xxxxxx> wrote:
>More or less a resend of v2.
>
>On Wed, Mar 26, 2014 at 06:03:37PM -0700, H. Peter Anvin wrote:
>> I'm wondering more about the default. We default to 50% for
>arch_get_random_seed, and this is supposed to be the default for in
>effect unverified hwrngs...
>
>Done. 50% is now the default, that's the only change from v2.
>
>Andy: the printk you pointed out already limits itself to 1/10s,
>which is half the default rate limit. Also, as Peter already
>wrote, we're dealing with true HWRNGs here; if such a device
>does not produce a single byte within 10 seconds something _is_
>severely broken and, like a dying disk, worth to be logged.
>Here's one of the better circuits I found:
>http://www.maximintegrated.com/app-notes/index.mvp/id/3469
>or offline:
>http://pdfserv.maximintegrated.com/en/an/AN3469.pdf
>Disclaimer: I'm not endorsing Maxim, it's just that paper
>that hits the spot IMHO.
>
>Anything wrong with feeding those bits into the input pool?
>Any other comments on the code?
>
> Torsten

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