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Re: kaslr: better rng

> Date: Mon, 6 Nov 2017 07:30:35 +0100
> From: Maxime Villard <>
> I would like to use a system similar to the /var/db/entropy-file
> implementation.  That is to say, when running the system generates
> /var/db/random-file, which would contain at least 256bytes of random
> data. When booting the bootloader reads this file, can use some of
> its bytes to get random values. It then gives the file to the
> prekern which will use some other parts of it. The prekern finally
> gives the file to the kernel which can use the rest.

Seems to me we should just use one file, and the bootloader should use
it as a seed for a PRNG from which it draws

(a) kaslr bits, and
(b) a seed for the entropy pool (which is currently just /var/db/entropy)

The bootloader already reads a file.  Teaching it to have a small
cryptographic PRNG shouldn't be too hard.  I'm still sitting on a
draft Keccak-based entropy pool, whose Keccak implementation
( likely fits in the
constraints of a bootloader.

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