Subject: [Privacy-pass] Documents adopted & next steps

From: Alex Davidson <[email-masked]>
Date: Mon, 19 Oct 2020 12:25:27 +0100

Hi all,

Firstly, I just wanted to thank the chairs for completing the adoption
call for each of the existing documents. In addition, the original
GitHub repo that the drafts were being worked on in has been transferred
to the privacy-pass WG organization: 
https://github.com/ietf-wg-privacypass/base-drafts.

Secondly, to kickstart the discussion on the next phase of work, I just
wanted to highlight some of the main outstanding issues that currently
need to be fixed with the existing documentation. As a start, below are
some meta-problems that I am aware of, based on the list on GitHub
(https://github.com/ietf-wg-privacypass/base-drafts/issues).

Protocol (related issues: #40):

- Define a publicly verifiable version of the protocol with proven
   security guarantees.

Architecture (related issues: #39, #20):

- Discuss the structure of any additional token metadata, and what
   the concrete threshold on number of bits.
- Discuss how clients should choose which servers they interactwith,
   and specify any additional characteristics that should be made
   available.
- What are the most appropriate mechanisms for removing the limitations
   on the number of token issuers in any ecosystem.

Centralization (related issues: #45, #47):

- What are the impacts of server centralization?
- What mitigations should be put in place to prevent centralization in
   the protocol architecture?
- How should the discussion be presented/documented?

HTTP API (related issues: #48):

- What assumptions are we making on the transport protocol that is being
   used for conveying Privacy Pass data.
- What additional information should be made available in each server's
   active key configuration? (For example, the domains that are supported
   for token redemption? Which running modes are being used?)

I have probably not covered the full surface of issues so please feel
free to add anything here, or start a new thread, if there is something
missing. There are also some smaller issues that still need to be solved
on GitHub. In general, it would really useful to have some more mailing
list discussions on these points (or any others) to establish more
concrete proposals.

Going forward, I think it would be worthwhile for us to aim to produce
-01 versions of the documents in time for an interim meeting after
IETF109. I expect that some of the bigger points such asspecifying
new protocol versions, and further discussion of the centralization and
tokenmetadata aspects may need an in-person discussion to clarify some
of the keyrequirements and solutions.

I hope this helps, and looking forward to future discussions!

Thanks,
Alex