WireGuard deployment considerations for improved privacy

[Jose Marinez]

Hi Fredrik,
I appreciate this proposition as well as your summary for the current state of Wireguard for this particular case. I agree with you wholeheartedly that before the mass adoption of Wireguard happens these use cases should be addressed properly. I'd love to hear what Jason has to say about this and what he proposes.
I too have been thinking about all the edge cases for Wireguard. My approach has been to look at it from a penetration test perspective. Reality is that Wireguard doesn't live in isolation. As a system - hardware, OS and all it's settings + Wireguard - connected to the Internet and a user(s) presents many hostile dynamics.
Ultimately, whatever solution emerges needs to supplement the goals and features of Wireguard, otherwise it deafts the purpose. 
Would it make sense to create a small group to tackle this and other use cases - scaling, simplicity, etc? On my end, I'm not a cryptologist, but I can write software that would test the security of any system. I'm sure other members of this list have a ton of skills and experience to bring to this. 
Here's a list of things I'd like to see and would be willing to participate/create if they don't exist yet:
1. A honeypot server with public logs for a small team to gather and record real-time traffic as an authorized user of the server - root.2. A test suite that goes through all the domain specific scenarios from the results of #1 and provides a verification at the end once completed.3. Provide feedback from all this back to Jason for enhancements, etc. in upstream Wireguard.
Feel free to reach out off-list.

Thanks,Jose

On Tuesday, January 15, 2019, 9:27 AM, Fredrik Strömberg <stromberg at mullvad.net> wrote:

On Tue, Jan 15, 2019 at 1:05 PM Henning Reich <henningreich at gmail.com> wrote:
>
> Thank for your reply too,
>
> I "use" this list and conversation to get a bit more information about crypto at all (it looks like I need that :-)
>
I see. When I wanted to learn more about network security protocols I
read the RFC for TLS from start to finish a few times. Every time I
didn't understand a word or concept I looked it up on Wikipedia, often
reading the entire article on that concept. In your case maybe read
the WireGuard paper a few times and reference Wikipedia. That's a good
start.

> I try to explain how I understood the problem, and anybdoy can tell me, where I have make a mistake :-)
> From https://www.wireguard.com/protocol/#key-exchange-and-data-packets
> the initiation message and the response use
> initiator.ephemeral_private = DH_GENERATE() and
> responder.ephemeral_private = DH_GENERATE()
>
Correct. Although to be exact DH-Generate returns a keypair (private, public).

> This means (I think), that for every new connection, a new DH-Key is generated. For me (not a programmer) it looks like all other private informations in the messages a encrypted/hashed with values derived from this DH-Key.

Almost. It uses Diffie-Hellman with the ephemeral private key as one component.

In the first message, msg.static is encrypted using a key derived from
DH of the Initiator's ephemeral private key, and the Responder's
static public key (which is already known to Initiator). The first
message also includes the field msg.ephemeral which contains the
Initiator's ephemeral public key, transmitted in the clear.

When the message is received by the Responder, she is able to decrypt
msg.static and learn the Initiator's static public key. You might ask
how that is possible when she doesn't have the Initiator's ephemeral
private key. The reason is that she can derive the correct encryption
key using the Initiator's ephemeral public key, previously transmitted
in the clear, and her (the Responder) static private key.

ECDH ( Initiator's ephemeral private key, Responder's static pubkey )
=
ECDH ( Initiator's ephemeral public key, Responder's static private key )

> Because both site knows the other static key, I would look in the "XX" Row, and there is your quoted destination proberty not exisintg.
>
WireGuard uses Noise_IK, not Noise_XX.

> It's probably possible that I ignore some cryptographic basics or misunderstood same facts. So I hope somebody takes the time and give me some more hints. Thanks
>
No worries. We're all learning something. If you want to learn more
about cryptographic protocols just put in the time. And when you don't
understand something, or suspect that you are wrong, read the whole
thing again. That's what I did :)

Cheers,
Fredrik
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