Re: [PATCH v3] OpenVPN: New AES-GCM cipher for N2N and RW

[Michael Tremer <michael.tremer@ipfire.org>]

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Hi,

some ECC in OpenVPN would be really nice. We have that in IPsec for quite a
while now and it makes the tunnels come up a lot faster and we can assume that
it is more secure, too.

ChaCha20-Poly1305 is quite interesting, too. It is an AEAD just like AES-*-GCM.
It is supposed to be really fast on mobile devices and an alternative to AES. We
only have one other alternative to AES which is Camellia. But that one does not
seem to receive a lot of love these days.

In contrast to Camellia, AES is usually hardware-accelerated whereas ChaCha20
can be implemented very efficiently in software that it does not consume too
much CPU time at all. Perfect for mobile to save battery life.

Probably there is not very good support for ChaCha20-Poly1305 out there. So AES
will be the default, but we would have a very good alternative for anyone who
know what they are doing.

Best,
-Michael

On Mon, 2018-02-26 at 07:48 +0100, ummeegge wrote:
> Hi Michael,
> 
> Am Sonntag, den 25.02.2018, 17:06 +0000 schrieb Michael Tremer via
> Development:
> > Hi,
> > 
> > I suppose this looks alright.
> 
> OK
> 
> > 
> > Does OpenVPN 2.4 support ChaCha20-Poly1305, too?
> 
> Yes, but i think only via the '--tls-cipher' directive which IPFire
> currently do not supports via WUI. Made a quick try over the
> server.conf.local and the additional configuration.
> 
> server.conf.local entries:
> 
> tls-version-min 1.2
> tls-cipher TLS-ECDHE-RSA-WITH-CHACHA20-POLY1305-SHA256
> 
> whereby the server logs points the following out: 
> 
> Feb 26 07:19:47 ipfire-prime openvpnserver[10190]:   cipher_list = 'TLS-ECDHE-
> RSA-WITH-CHACHA20-POLY1305-SHA256'
> 
> But in general we step into a new crypto era with OpenVPN since ECC is now
> fully integrated in OpenVPN.
> 
> Under the hood we will discover now also ECDHE for the control channel without
> changing anything so the EC crypto is now partly available 
> with Core 120.
> 
> But pure elliptic curve crypto is also possible e.g.
> https://forums.openvpn.net/viewtopic.php?t=23227
> but this would be a huge amount of changes in ovpnmain.cgi but may it is worth
> it. Let´s see...
> 
> > 
> > -Michael
> 
> Greetings,
> 
> Erik
>