Add SRI hash to existing CDN links

I have a Drupal site where there are few CDN links. Iwas thinking of adding SRI hashes to those links.

How can I do that?

Every solution I tried requires to add a custom module, but I don't know how these things work.

Somehow, I managed to create a custom module which creates a Hello page. I just followed a tutorial. Can I add hashes in it?

sri.info.yml

name: SRI Hash
type: module
description: 'SRI Hash'
package: custom
version: 8.x
core: 8.x

sri.routing.yml

sri.scripthash:
  path: '/sri_hash'
  defaults:
    _controller: '\Drupal\sri\Controller\SriController::scripthash'
    _title: 'SRI Hash'
    requirements: 
      _permission: 'access content'

SriController.php

namespace Drupal\sri\Controller;

class SriController {
  /**
   * Returns a simple page.
   *
   * @return array
   *   A simple renderable array.
   */
  public function scripthash() {
    $element = array(
      '#markup' => 'This is a page !',
    );
    return $element;
  }
}

Is there another way to do it?