I'm requesting TAG input on some design questions we discussed at the 2019-02 Tokyo meeting. https://github.com/w3ctag/design-reviews/issues/235 is already closed, so I'm filing a new issue.

• Name: Signed Exchanges
• Specification URL: https://wicg.github.io/webpackage/loading.html and https://wicg.github.io/webpackage/draft-yasskin-http-origin-signed-responses.html
• Explainer, Requirements Doc, or Example code: https://github.com/WICG/webpackage/
• Tests: https://github.com/web-platform-tests/wpt/tree/master/signed-exchange
• Primary contacts: @jyasskin, @nyaxt

Questions:

1. Do you have ideas to help ensure that web servers don't sign personalized content, which can allow various attacks?
   1. Does it make sense/help things to require that a signed exchange is fetched with credentials="omit"? This requires at least a new attribute on <a> tags to set its credentials mode and Fetch infrastructure to handle that on navigations.
2. How would you trade off the extra security of validating content in real time vs the surveillance that allows?
3. Similarly, do you have ideas on how best to notify a publisher that their certificate has signed such-and-such exchange, without revealing private information about who's reading the content? https://github.com/WICG/webpackage/issues/376 could handle this ... by revealing that private information.

We'd prefer the TAG provide feedback as (please select one):

• open issues in our Github repo for each point of feedback
• open a single issue in our Github repo for the entire review
• leave review feedback as a comment in this issue and @-notify [github usernames]