Hi,
On Mo, 2019-06-10 at 20:12 +0100, Michael Tremer wrote:
Hi,
On 10 Jun 2019, at 20:08, Peter Müller peter.mueller@ipfire.org wrote:
Hello Michael,
thanks for your comments.
Hi,
I think I can ACK this although we definitely should change the default. I have raised that a couple of times before.
Yes. This is true for IPsec as well... Patch is in my pipeline…
Okay. Can we try to make a patchset out of things like this in the future?
That keeps things together and we can coordinate better when we merge this.
We have closed the last Core Update technically last week. Now we have some big changes here and I would prefer to not break the update but have it rather shipped as soon as possible.
I also do not like having a very long list of ciphers that are weak. There are not too many left which are “strong”. But yeah, what can you do?
As far as I am concerned, there is little "strong" cryptography left indeed. It's basically only TLS >= 1.2 with AEAD (e.g. GCM) ciphers and Forward Secrecy.
Speaking about RFC 8446, this is more or less what survived discussions before standardizing TLS 1.3 ... :-)
Yeah I picked up on that too, but we have to make sure that we ensure compatibility.
OpenVPN is hard to update. People cannot migrate from a cipher to another one and not all versions support GCM.
A helpful feature for this is --ncp-ciphers where we have had also some discussions some time ago. In principle it is only a checkbox but choosing the ciphers is more work also if we want to have a separate encryption section in the WUI.
Another point which matches this topic i think is the DH-parameter which is, i think, for updated systems (OpenVPN-2.4.x) useless since mostly key exchanges are meanwhile managed via ECDH. We tested this with 'dh none' --> https://forum.ipfire.org/viewtopic.php?f=50&t=22664 . But this is again another encryption setting which is also in my opinion an advanced one in his specifics but a good candidate for a default. We could also spare then the DH-parameter while PKI generation (which needs really lot´s of time and can causes also troubles for weak machines and long paramters). An DH-upload possiblity can still be there for example to keep the possibility for backwards compatibility). Did also some work on this but my time is currently really really rare!
-Michael
I will wait for Erik to ack this, too.
I think we have two kinds of "weak" then. The 64bit block ciphers do have also some technical disadvantage since Sweet32 a renegotiation is forced after 64MB which can be fast reached. So we have a kind of "very weak" and "weak" then?
-Michael
Thanks, and best regards, Peter Müller -- The road to Hades is easy to travel. -- Bion of Borysthenes
Some thoughts from here.
Best,
Erik