[Secdispatch] Dispatching draft on key consistency

[Christopher Wood <[e-mail]>]

There are a number of different protocols that require multiple clients to discover a common — or consistent — cryptographic public key for use, including: Privacy Pass [1], Oblivious DoH [2], and Oblivious HTTP [3]. Consistency here means that all clients obtain the same view of the public key. An inconsistent view can lead to privacy attacks. 

For example, in Privacy Pass, if an attacker can somehow force a single (set of) client(s) to use a public key that is distinct from all other clients, then the key used effectively partitions the set of clients into two buckets, and the size and number of these partitions influence the overall privacy posture of the protocol. 

As this was a pattern across at least two disjoint protocols, we felt it would be useful to document some approaches for building key consistency into systems. The result is [4]. This has been previously presented in the context of the Privacy Pass working group [5], but was not pushed forward as a work item. 

We’d like to ask for time during SECDISPATCH to (a) determine if there’s interest in moving this document forward in some way, and if so, (b) determine what venue would be best to move it forward.

Thanks,
Chris, for the authors

[1] https://datatracker.ietf.org/wg/privacypass/about/
[2] https://datatracker.ietf.org/doc/draft-pauly-dprive-oblivious-doh/
[3] https://ietf-wg-ohai.github.io/oblivious-http/draft-ietf-ohai-ohttp.html
[4] https://datatracker.ietf.org/doc/draft-wood-key-consistency/
[5] https://datatracker.ietf.org/doc/slides-110-privacypass-key-consistency-and-discovery/