Intent to Prototype: User-Agent Client Hints "ch-ua-high-entropy-values" permissions policy
Mike Taylor
Contact emails
Explainer
See Motivation below.
Specification
https://wicg.github.io/ua-client-hints/#ch-ua-high-entropy-values
Summary
Adds support for a 'ch-ua-high-entropy-values' permissions policy that enables a top-level site to restrict which documents are able to collect high-entropy client hints via the navigator.userAgentData.getHighEntropyValues() JS API.
Blink component
Motivation
Currently it's only possible to restrict third-party collection of high-entropy User-Agent Client Hints when they're requested over HTTP (via the various permissions policies associated with each Client Hint, i.e., https://wicg.github.io/client-hints-infrastructure/#policy-controlled-features).
The permissions policy proposed by this change allows a first-party site to have more control over which third parties are allowed to request high-entropy client hints via the getHighEntropyValues() JS API, which could be deployed alongside the other permissions policies.
Initial public proposal
https://github.com/WICG/ua-client-hints/issues/151#issuecomment-783668130
Interoperability and Compatibility
Gecko: Neutral. :mt had previously commented that new UA-CH features should defer to their official position.
WebKit: Not requested yet. But the initial issue that prompted this feature was filed as feedback from WebKit.
Web developers: Informal support from a conversation with a developer working on a privacy-focused search engine who was interested in this feature.
WebView application risks
Nothing special here
Is this feature fully tested by web-platform-tests?
Yes, WPTs will be added
Flag name on about://flags
None
Finch feature name
ClientHintUAHighEntropyValuesPermissionPolicy
Requires code in //chrome?
False
Tracking bug
https://issues.chromium.org/issues/385161047
Launch bug
https://launch.corp.google.com/launch/4366844
Estimated milestones
No milestones specified
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/6176703867781120?gate=4953839037579264