[gnutls-devel] lock-free random generator

[Nikos Mavrogiannopoulos]

On Mon, Feb 20, 2017 at 8:14 AM, Nikos Mavrogiannopoulos
<n.mavrogiannopoulos at gmail.com> wrote:

>> For the yarrow reseed logic, I think it may be preferable with a global instance.
> If we need yarrow, your recommendation seems to be the right approach.
> However, another thought it has been bugging me lately, is whether we
> need yarrow in gnutls. It looks quite suited for something central
> like /dev/urandom which has several maybe untrusted inputs, but for
> gnutls which seeds from /dev/urandom (or the equivalent system calls),
> having a PRNG which concerns itself with manipulation of input may not
> be adding the security it is perceived to add.

And to answer myself, I do not think we need something complex as
yarrow in gnutls. Older systems may have needed it, but today we can
rely on /dev/urandom and getentropy() interfaces, and as such I no
longer it is necessary to bring that complexity to gnutls.

I've redesigned the whole random generator and provided a high level
description at:
https://gitlab.com/gnutls/gnutls/blob/c6a01ff6c5a44a19b5f6dba9280da96cc28f92d8/doc/cha-crypto.texi#L111

The corresponding code is at:
https://gitlab.com/gnutls/gnutls/merge_requests/259

regards,
Nikos