Subresource prefetching+loading via Signed HTTP Exchange

Adds support signed exchange subresource prefetching and loading by extending the HTTP link header.

Motivation

Signed Exchanges allow a distributor to distribute content signed by a publisher and have the UA show the publisher's URL, give scripts access to the publisher's local storage, etc. However, the URLs of subresources are fixed in the signed top-level HTML file, which prevents their loads from taking advantage of any signed versions that might be prefetched the distributor's origin. To allow the subresources to be prefetched from the same distributor as the top-level page,the publisher needs to change the subresource URLs in the HTML to point to each distributors’ URL and needs to sign for each distributor. We want to allow publishers to create a single signed top-level HTML file that allows its subresources to be prefetched from a variety of distributors.

Demo

Documentation

Specification

Public discussion

Status in Chromium

Blink>Loader


Enabled by default (tracking bug) in:

  • Chrome for desktop release 85
  • Chrome for Android release 85

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.

  • No signal
  • No signal
  • No signal
  • Positive

Owners

Intent to Prototype url

Intent to Prototype thread

Last updated on 2020-10-25