[Ohai] The last few OHTTP issues

[Martin Thomson <[e-mail]>]

As the chairs noted in the conclusion to WGLC a couple of non-trivial issues were raised during last call.

# Bad Key Configuration

https://github.com/ietf-wg-ohai/oblivious-http/issues/194 

In ODoH deployment experience thus far, this appears to be the most common problem as devices wake from a long sleep and the server has rotated keys.  So the idea is that it might be helpful for a gateway to indicate to a client that a key configuration was bad.

The proposed resolution is here: https://github.com/ietf-wg-ohai/oblivious-http/pull/196

The substance of that pull request is that we are defining a signal with RFC 7807 (specifically, the revision that the HTTPAPI WG are finishing up).  There's also some text on why any signal like this that isn't encrypted might be unreliable and how clients might want to use a heuristic for refreshing key configurations as a backstop.

# Asynchronous Submission

https://github.com/ietf-wg-ohai/oblivious-http/issues/179

The question is what you might do if the relay or gateway decide to store a request and deal with it later.  The use case for this is a submission service where the content of the response isn't interesting to the client.  In particular, this might allow a gateway to keep its key offline somewhere if it doesn't have to encapsulate a response.

The discussion there resolved on keeping this out of scope. It looks like this is entirely possible without new specification work, just with existing HTTP semantics (202, specifically).  There's a draft draft floating around somewhere that walks through some of the implications in more detail.

That outcome seemed uncontroversial, so we have already closed the issue, but it's worth raising here in case we overstepped.

# Action

I'd like to merge the remaining pull requests next week, on Thursday-ish.  Please review the issues and let the editors know before the end of the month if you disagree with the direction we've proposed.

Unless our esteemed chairs disagree, this will be the last change before we revise the draft in preparation for publication.