[dns-privacy] Adaptive DNS Privacy and Oblivious DoH

[Tommy Pauly <[e-mail]>]

Hello DNS Privacy,

We’ve published a set of new drafts that define what we’re calling “Adaptive DNS Privacy”. This is an approach to using technologies like DoH to improve privacy of name resolution without breaking the functionality provided by local network resolvers. It also does not require placing trust in one or more fixed resolvers, but instead allows server deployments to dynamically indicate which resolvers are designated for their zones.

From the perspective of an operating system vendor (for myself, iOS and macOS), the goal is to use this approach to DNS privacy in the system stub resolver such that it can be safely and automatically used by all applications.

The first draft is “Adaptive DNS: Improving Privacy of Name Resolution”.
https://tools.ietf.org/html/draft-pauly-dprive-adaptive-dns-privacy

This covers the overall architecture for both clients and server deployments. This includes:

	• A mechanism for clients to discover DoH resolvers that are “designated” for certain names or zones, using a DNSSEC-signed SVCB record (https://tools.ietf.org/html/draft-nygren-dnsop-svcb-httpssvc).
	• An algorithm for clients to select which resolver to use for a given name based on precedence (defining how VPNs, local network resolvers, designated cloud-based resolvers, and Oblivious DoH lookups coexist).
	• A mechanism for local networks to advertise their rules and capabilities using a provisioning domain (https://tools.ietf.org/html/draft-ietf-intarea-provisioning-domains); this allows the advertisement of a locally-designated DoH server, a list of names or zones over which the local network claims authority, and an indication of filtering requirements.

The second draft is “Oblivious DNS Over HTTPS”, which we refer to as ODoH. 
https://tools.ietf.org/html/draft-pauly-dprive-oblivious-doh

Inspired by Oblivious DNS (https://tools.ietf.org/html/draft-annee-dprive-oblivious-dns), this draft adds an extension to DoH for encrypting queries such that a resolver cannot know both the client’s IP address and the content of the DNS query. In contrast to Oblivious DNS, ODoH uses HTTP proxying to unlink query sources and destinations. (ODoH also uses HPKE (https://tools.ietf.org/html/draft-irtf-cfrg-hpke) for query public key encryption.)

Please take a read through the documents and provide feedback. We’re eager to iterate on these goals with the community.

You can also provide feedback and input on the GitHub repo: https://github.com/tfpauly/draft-pauly-adaptive-dns-privacy.

If you are interested in working on implementing any of these protocols, please reach out for interop testing, etc. 

Best,
Tommy, Chris, Eric, and Patrick