[DNSOP] Light weight encrypted DNS proposal

[Vint Joseph <[e-mail]>]

Hello All,

I hope you're all doing well.

We wanted to share an idea regarding encrypted DNS and get your thoughts on
it. Our goal is to make the setup for encrypted DNS as simple as our
current DNS setup. Here are a few key points:
- Simplicity: Ideally, the setup should be as straightforward as possible,
using UDP and only one or two packets.
- Cost Efficiency: The encryption and decryption processes should not
introduce significant overhead.
- Stateless Approach: Maintaining state on both the client and server sides
is costly. While we might not be able to completely move out of stateless
ideas, we try to maintain this core concept
- UDP Benefits: Using UDP can help avoid the head-of-line blocking issues
we see with TCP.
- Considering QUIC: While QUIC is a potential solution, it has its own
complexities, including retransmission mechanisms. We're okay with some
packet loss if retransmitting DNS queries remains simple (one or two
packets).
- Crypto Agility: This idea prioritizes simplicity and doesn't fully
address the need for crypto agility.
I would greatly appreciate your input on this approach and any suggestions
you might have for improvement.

The core idea/synopsis
We plan to implement a system using elliptic curve cryptography. A
preshared key, referred to as the public key G^S, is distributed from the
dns server to the client. The server retains the private key S and the
corresponding public key G^S, while the client receives the public key G^S.
When the client needs a DNS response, it generates a key pair consisting of
a private key C and a public key G^C. The client then sends a DNS request
encrypted with the shared key G^CS and includes its public key G^C in the
DNS extension. Upon receiving the public key G^C, the DNS server computes
the shared key G^CS using its private key S and the client's public key
G^C. These are ephemeral keys, ensuring that each DNS packet has its own
session keys. The DNS server responds to the DNS query and sends the DNS
response encrypted using G^CS. If the DNS server plans to change the keys,
then a public key G^S1 is sent to the client , in the response packet. But
these are optimizations which can be done later.
Thank you and I'm looking forward to your feedback!

Best regards,
Vineeth