Serve private images using signed URL tokens

If an image is marked to require a signed URL, it cannot be accessed without a token unless it is being requested for a Variant that is set to always allow public access.

1. Log in to the Cloudflare dashboard Open external link , and select your account.
2. Click Images > Keys.
3. Copy your key and use it to generate an expiring tokenized URL. Here is an example Worker script that takes in a regular URL without a signed token and returns a tokenized URL that expires after one day. You can, however, set this expiration period to whatever you need, by changing the const EXPIRATION value.

   const KEY = 'YOUR_KEY_FROM_IMAGES_DASHBOARD';
   const EXPIRATION = 60 * 60 * 24; // 1 day
   
   const bufferToHex = buffer =>
     [...new Uint8Array(buffer)].map(x => x.toString(16).padStart(2, '0')).join('');
   
   async function generateSignedUrl(url) {
     // `url` is a full imagedelivery.net URL
     // e.g. https://imagedelivery.net/cheeW4oKsx5ljh8e8BoL2A/bc27a117-9509-446b-8c69-c81bfeac0a01/mobile
   
     const encoder = new TextEncoder();
     const secretKeyData = encoder.encode(KEY);
     const key = await crypto.subtle.importKey(
       'raw',
       secretKeyData,
       { name: 'HMAC', hash: 'SHA-256' },
       false,
       ['sign']
     );
   
     // Attach the expiration value to the `url`
     const expiry = Math.floor(Date.now() / 1000) + EXPIRATION;
     url.searchParams.set('exp', expiry);
     // `url` now looks like
     // https://imagedelivery.net/cheeW4oKsx5ljh8e8BoL2A/bc27a117-9509-446b-8c69-c81bfeac0a01/mobile?exp=1631289275
   
     const stringToSign = url.pathname + '?' + url.searchParams.toString();
     // for example, /cheeW4oKsx5ljh8e8BoL2A/bc27a117-9509-446b-8c69-c81bfeac0a01/mobile?exp=1631289275
   
     // Generate the signature
     const mac = await crypto.subtle.sign('HMAC', key, encoder.encode(stringToSign));
     const sig = bufferToHex(new Uint8Array(mac).buffer);
   
     // And attach it to the `url`
     url.searchParams.set('sig', sig);
   
     return new Response(url);
   }
   
   addEventListener('fetch', event => {
     const url = new URL(event.request.url);
     const imageDeliveryURL = new URL(
       url.pathname.slice(1).replace('https:/imagedelivery.net', 'https://imagedelivery.net')
     );
     event.respondWith(generateSignedUrl(imageDeliveryURL));
   });