Re: Establishing consistent opt-ins to expose resource metadata

High-level question: are metadata and data distinct enough and can
developers-at-large reason about their difference to make the right
trade-offs? At least in terms of surveillance, metadata can tell a
pretty damning story as we've come to learn and I know the
network-security folks are trying their best not to give any bits to
the network, e.g., I worry a bit
that what we're doing here isn't exactly sound from an
information-security perspective.

On Sat, Jul 18, 2020 at 6:42 PM Artur Janc <> wrote:
> 1. Use individual, per-feature HTTP headers to allow exposing individual properties of the response, or a single header (e.g. `Metadata-Allow-Origin` to collect opt-ins into a single header. If we do this, we could merge `Timing-Allow-Origin` into this header.

Modulo the above, this seems fine.

> 2. Use the presence of CORP as a signal that (some) metadata about the resource can be revealed. This seems scary at first glance, but setting CORP already serves as an opt-in to allow the resource to be embedded in COOP+COEP contexts, which may be able to read the whole resource from their process memory -- developers shouldn't set CORP: `cross-site` on authenticated responses that they're worried about leaking cross-origin.

I don't like this. In the face of a Spectre-read gadget, CORP "equals
CORS", but only then. Google's suggestion to switch from CORS to CORP
for cross-origin isolated was good I think and gave me renewed hope
that we'll eventually get rid of Specre either through hardware/kernel
or changes in browser architecture.

> 3. Extend Mike and Kinuko's Resource Policy proposal ( to combine the two approaches above. Specifically, with an extended syntax, we could have the header specify both _who_ can embed a resource, and _how_ the resource can be used.

I guess now that we have structured headers we need to relearn what
the right amount of headers is. I think I personally side with Noam
that unless they are intertwined it seems best to keep them separate.

Received on Monday, 20 July 2020 09:55:32 UTC