AMP-Toolbox Script CSP

Calculates the Content Security Policy (CSP) hash for the given script in the format expected by amp-script.

CSP is required when using amp-script with inline or cross-origin scripts.

Usage

Install via:

$ npm install @ampproject/toolbox-script-csp

Using the module

The module exposes a single function, calculateHash(src, options?).

src can be either a string (in which case UTF8 encoding is assumed) or a DataView such as a Buffer.

options is used to override the default options.

Options

• algorithm overrides the hashing algorithm to use. Currently, the only algorithm supported by amp-script is sha384 which is the default value.

Example

Here is an example on how to use the calculateHash function to generate an amp-script CSP header.

Note that both leading and trailing whitespace is included in calculating the hash and must exactly match the whitespace used in the inline script.

const {calculateHash} = require('@ampproject/toolbox-script-csp');

const script = `
    const subject = 'world';
    console.log('Hello, ' + subject);
    `;

const hash = calculateHash(script);

console.log(hash);  // sha384-xRxb5sv13at6tVgZET4JLmf89TSZP10HjCGXVqO9bKWVXB0asV2jLrsDN8v4zX6j

The generated hash can be used in a <meta> tag this way:

<!doctype html>
<html ⚡>
<head>
  ...

  <meta name="amp-script-src" content="sha384-xRxb5sv13at6tVgZET4JLmf89TSZP10HjCGXVqO9bKWVXB0asV2jLrsDN8v4zX6j">
</head>
  <body>
    ...

    <amp-script layout="container" script="example"></amp-script>

    <script id="example" type="text/plain" target="amp-script">
    const subject = 'world';
    console.log('Hello, ' + subject);
    </script>
  </body>
</html>