Integrity-Policy header

The HTTP Integrity-Policy response header allows website administrators to ensure that all resources the user agent loads (of a certain type) have Subresource Integrity guarantees.

When set the user agent will block requests on specified request destinations that omit integrity metadata, and will also block requests in no-cors mode from ever being made. This helps guard against content manipulation of fetched subresources.

Violations of the policy may be reported using the Reporting API. Reports can be observed in the page for which the policy is being enforced, using a ReportingObserver, and sent to server endpoints defined in a Reporting-Endpoints HTTP response header and selected using the endpoints field. For more information see IntegrityViolationReport.

Header type	Response header

Syntax

http

Integrity-Policy: blocked-destinations=(<destination>),sources=(<source>),endpoints=(<endpoint>)

The header values are defined as structured field dictionaries with the following keys:

blocked-destinations

A list of request destinations that must include valid integrity metadata. Allowed values are:

script: Script resources.
style: Stylesheet resources.

sources Optional

A list of integrity sources that must include integrity metadata. Allowed values are:

inline

The integrity metadata source is inline to the content, such as the integrity attribute. This is the default.

As this is the default and only value, omitting sources is equivalent to specifying sources=(inline).

endpoints Optional

A list of reporting endpoint names that indicate where reports will be sent. The reporting endpoints must be defined in a Reporting-Endpoints header.

Examples

Blocking and reporting when scripts lack integrity metadata

This example shows a document that blocks and reports to a server endpoint when any <script> (or HTMLScriptElement) does not specify an integrity attribute, or when a script resource is requested in no-cors mode.

Note that the integrity-endpoint used in Integrity-Policy is defined in the Reporting-Endpoints header.

http

Reporting-Endpoints: integrity-endpoint="https://example.com/integrity", backup-integrity-endpoint="https://report-provider.example/integrity"
Integrity-Policy: blocked-destinations=(script), endpoints=(integrity-endpoint backup-integrity-endpoint)

The report payload might look like this.

json

{
  "type": "integrity-violation",
  "url": "https://example.com",
  "body": {
    "documentURL": "https://example.com",
    "blockedURL": "https://example.com/main.js",
    "destination": "script",
    "reportOnly": false
  }
}