CSP: trusted-types

The HTTP Content-Security-Policy (CSP) trusted-types directive instructs user agents to restrict usage of known DOM XSS sinks to a predefined set of functions that only accept non-spoofable, typed values in place of strings. This allows authors to define rules guarding writing values to the DOM and thus reducing the DOM XSS attack surface to small, isolated parts of the web application codebase, facilitating their monitoring and code review. This directive declares a white-list of trusted type policy names created with TrustedTypes.createPolicy from Trusted Types API.

Syntax

Content-Security-Policy: trusted-types;
Content-Security-Policy: trusted-types <policyName>;
Content-Security-Policy: trusted-types <policyName> <policyName> 'allow-duplicates'; 

<DOMString>

Any string can be a Trusted Type policy name.

'allow-duplicates'

Allows for creating policies with a name that was already used

Examples

TODO

Polyfill

A polyfill for Trusted Types is available on Github.

Specifications

Browser compatibility

See also

• Content-Security-Policy
• Cross-Site Scripting (XSS)
• Google Developers: Intro to Trusted-Types
• Trusted Types with DOMPurify XSS sanitizer