WooCommerce Webhooks Auth (secret & signature) - how to use

The signature needs to be checked against the body and not the JSON it contains. i.e. the raw bytes of the req.body.

Modify the bodyParser first:

const rawBodySaver = (req, res, buf, encoding) => {
  if (buf && buf.length) {
    req.rawBody = buf.toString(encoding || 'utf8');
  }
};

app.use(bodyParser.json({ verify: rawBodySaver }));
app.use(bodyParser.urlencoded({ verify: rawBodySaver, extended: true }));
app.use(bodyParser.raw({ verify: rawBodySaver, type: '*/*' }));

and then, using crypto (it is distributed with node you don't need to npm install anything.)

import crypto from 'crypto'; //Let's try with built-in crypto lib instead of cryptoJS

router.post('/', function (req, res) {
  const secret = 'ciPV6gjCbu&efdgbhfgj&¤"#&¤GDA';
  const signature = req.header("X-WC-Webhook-Signature");

  const hash = crypto.createHmac('SHA256', secret).update(req.rawBody).digest('base64');

  if(hash === signature){
    res.send('match');
  } else {
    res.send("no match");
  }
});

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