Re: [PATCH] Mark recommended ciphers/algorithms

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

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Hi,

On Sat, 2016-01-02 at 14:03 +0100, ue wrote:
> Hi all,
> and for the first a good new year to you all.
> > 
> > I agree, that it is desirable to use longer keys. However, I am not
> > sure if it is a good idea to go all the way for 4096 bit and not
> > only
> > for e.g. 2048 bit. Why not 8192 even?
> > 
> > I would like to read some justification for the values that are
> > picked.
> > 
> > Furthermore, I think that we the upper bound should be something
> > that
> > the average IPFire box is able to handle.
> 
> 
> tried that now with OpenVPN whereby i added a flip menu in the
> 'Generate Root/Host Certificate' section as it is for the Diffie
> -Hellman parameter so the keylengths aren´t hardcoded anymore and can
> be configured by the user. Added for the root CA 4096, 8192 and 16348
> tit lengths selection possibilities and for the host CA 2048, 4096,
> 8192 and also 16348 bit. The configured keylength for the host CA was
> also used for the control channel.

Is it even possible to use arbitrary key lengths with OpenVPN?

16k is really really long.

> The Root CA generation took 31 minutes for a 16348 bit keylength, the
> Host CA 12 minutes for 8192 bit and a 1024 bit DH-parameter needed 2
> minutes which is in summary ~ 45 minutes. The generation time differs
> also on every generation.
> The creation of a new client PKCS#12 package for 8192 bit needed  3
> minutes.
> The key exchange with a Control Channel: TLSv1.2, cipher TLSv1/SSLv3
> DHE-RSA-AES256-GCM-SHA384, 8192 bit RSA needed 10 sec.

This sounds increadible fast to me. We had devices on which that took
way longer.

I have recently seen a talk about using /dev/urandom instead. This is
probably worth a watch: https://www.youtube.com/watch?v=Q8JAlZ-HJQI

> 
> All tests was made with a JNC9C --> http://fireinfo.ipfire.org/profil
> e/72d11e77621ec66ea75d39e3c9b10025e746e5af and without HWRNG or PRNG
> .
> 
> If someone is interested in a ovpnmain.cgi diff and/or more testing
> results let it me know.

You can post it as a patch on here and add a note that this is for
testing only and not (yet?) intended to be merged.

> 
> 
> Greetings,
> 
> Erik

Best,
-Michael

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