Fwd: Re: /dev/urandom

Fwd: Re: /dev/urandom

[doncatnip]

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Of course, I forgot the CC here too.




-------- Forwarded Message --------
Subject: 	Re: /dev/urandom
Date: 	Wed, 11 Jul 2018 17:38:52 +0200
From: 	doncatnip <gnopap@gmail.com>
To: 	Vincent Legoll <vincent.legoll@gmail.com>



I'd guess this is about the distribution of blocks within the image, so
that the load of each sector is different from image to image containing
the same data. Of course, I'm just speculating as I haven't looked into
it - but if that is the case, it would seem even more strange that this
random seed is generated during install and not during use of the program.


On 7/11/2018 5:07 PM, Vincent Legoll wrote:
> On Wed, Jul 11, 2018 at 4:17 PM, Danny Milosavljevic
> <dannym@scratchpost.org> wrote:
>> the randomness is necessary for NAND wear levelling,
> Any pointers about that subject ?
>
> This looks strange as I'd have thought that less writes => less wear.
>


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Fwd: Re: /dev/urandom

[doncatnip]

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Of course, I forgot the CC.



-------- Forwarded Message --------
Subject: 	Re: /dev/urandom
Date: 	Wed, 11 Jul 2018 09:58:14 +0100
From: 	Steffen Schulz <gnopap@gmail.com>
To: 	Leo Famulari <leo@famulari.name>



I probably got it wrong.

but it seems the programs purpose is to build images (boot loaders). I
then wonder why it needs to do this during installation. If image
building is the programs purpose, it should happen during execution
after installation, no ?

Users would *most likely* prefer it's actual purpose (proper Images,
including optimization) instead of reproducibility.

On 10.07.2018 23:40, Leo Famulari wrote:
> On Tue, Jul 10, 2018 at 08:58:43PM +0200, Danny Milosavljevic wrote:
>> It writes an image file.  Since that image is later written to flash storage
>> (by the user), the program randomizes the data in order to increase longevity.
>> Then it stores the random data used as well.
> I see. Like Ludo and Mark, I think we should avoid doing tricky things
> with urandom.
>
> Could /dev/zero work here? Does it use urandom once, to get a seed, or
> does it read urandom repeatedly, expecting different values each time?
>
> Also, I wonder if Guix users would want reproducibility here instead of
> longer-lived NAND storage.


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