Re: [blink-dev] Intent to Ship: WebRequest.SecurityInfo in Controlled Frame

[Reilly Grant]

IWA OWNER LGTM, this is an extension to an existing IWA-specific feature. Thank you for finding a solution which fits within the existing Web Request API.

Note, this still needs 3 LGTMs from Blink OWNERS.

Reilly Grant | Software Engineer | rei...@chromium.org | Google Chrome

On Tue, Dec 9, 2025 at 4:17 AM Chromestatus <ad...@cr-status.appspotmail.com> wrote:

Contact emails

vk...@google.com

Explainer

https://github.com/explainers-by-googlers/security-info-web-request

Specification

https://github.com/WICG/controlled-frame/pull/151

Design docs

https://github.com/explainers-by-googlers/security-info-web-request

Summary

This proposal introduces a WebRequest.SecurityInfo API for ControlledFrame. It allows a web app to intercept an HTTPS, WSS or WebTransport request to a server, retrieve the server's certificate fingerprint (as verified by the browser), and then use that fingerprint to manually verify the certificate of a separate raw TCP/UDP connection to the same server. This provides a simple way for the app to confirm it's talking to the correct server.

Blink component

Blink

Web Feature ID

Missing feature

Motivation

Web apps sometimes need to establish secure raw TCP/UDP connections (e.g., via Direct Sockets) for custom protocols, often to support legacy servers that cannot be updated to modern alternatives like WebTransport. Unlike standard HTTPS, these raw sockets don't have a built-in mechanism to verify the server's TLS certificate against a trusted root store. This proposal introduces a WebRequest SecurityInfo API for ControlledFrame. It allows a web app to intercept an HTTPS, WSS or WebTransport request to a server, retrieve the server's certificate fingerprint (as verified by the browser), and then use that fingerprint to manually verify the certificate of a separate raw TCP/UDP connection to the same server. This provides a simple way for the app to confirm it's talking to the correct server.

Initial public proposal

https://github.com/WICG/proposals/issues/245

TAG review

Tag does not review Isolated Web Apps. It was stated publicly here https://github.com/w3ctag/design-reviews/issues/842#issuecomment-2917031448

TAG review status

Pending

Risks

Interoperability and Compatibility

Other browsers may choose to implement this API.

Gecko: No signal

WebKit: No signal

Web developers: No signals

Other signals:

Security

This API exposes the server's leaf certificate and fingerprint to the web app. This is not considered a new security or privacy risk. A web app with Isolated Context and the direct-sockets permission can already open a raw TCP connection to any server, perform a (D)TLS handshake using a WASM library, and retrieve the exact same server certificate.

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

No information provided

Debuggability

There's no devTools support for this feature. Since, this feature itself does not modify any web requests, it gives read-only view into server certificate.

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

No
This feature is implemented on desktop platforms, although it will only be available to the end users on platforms that support Isolated Web Apps, which is currently only ChromeOS. Android is excluded for historical reasons, although there are no apparent interoperability blockers here.

Is this feature fully tested by web-platform-tests?

No

Flag name on about://flags

controlled-frame-web-request-security-info

Finch feature name

kControlledFrameWebRequestSecurityInfo

Rollout plan

Will ship enabled for all users

Requires code in //chrome?

True

Tracking bug

https://g-issues.chromium.org/issues/462114142

Launch bug

https://launch.corp.google.com/launch/4436388

Measurement

Added new values to Extensions.WebRequest.EventListenerFlag which are securityInfo, securityInfoRawDer

Availability expectation

Feature is available only in Isolated Web Apps on desktop platforms. https://chromestatus.com/feature/5146307550248960

Adoption expectation

Expected to be used initially by a small number of developers inside Isolated Web Apps.

Adoption plan

Working directly with developers that are planning to rely on the API.

Estimated milestones

Shipping on desktop	147
DevTrial on desktop	145

Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).

No information provided

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5076692209106944?gate=6523426508505088

Links to previous Intent discussions

Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/691df8c4.050a0220.2a427a.06b0.GAE%40google.com

This intent message was generated by Chrome Platform Status.

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[Chris Harrelson]

LGTM1

To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAEmk%3DMa%3DyZM2rOO3v4BwThnPs7LtGz03OZF9HVom2djt2M-9AQ%40mail.gmail.com.

[Yoav Weiss (@Shopify)]

LGTM2 conditional on answers to the questions around tests

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[Alex Russell]

LGTM3 with the same conditions.

Best,

Alex