We’ve got a Node.js endpoint listening for .queue.member.added events. The goal is to verify the X-Genesys-Signature header to stop replay attacks. The docs say to base64-decode the header and compare it to an HMAC-SHA256 of the raw body using our client secret. It’s failing every time. The signature length looks right, but the comparison always returns false. Here’s the verification logic we’re using:
const crypto = require('crypto');
const sigHeader = req.headers['x-genesys-signature'];
const body = req.body;
const secret = process.env.GENESYS_CLIENT_SECRET;
const decodedSig = Buffer.from(sigHeader, 'base64').toString('utf8');
const calculatedSig = crypto.createHmac('sha256', secret).update(body).digest('base64');
console.log('Header:', decodedSig);
console.log('Calc: ', calculatedSig);
The console logs show completely different strings. The header decodes to something that looks like raw binary garbage, while the calculated signature is a clean base64 string. Are we supposed to hash the body before base64 encoding it again? Or is the header already hex-encoded? The documentation is vague on the exact byte format expected in the header versus what createHmac spits out.
Are you stripping newlines from the raw body before hashing? Node.js stream parsing often adds a trailing \n. That single character breaks the HMAC match. Try logging body.length vs the expected payload size. If it’s off by one, trim it.
const cleanBody = req.body.replace(/\n$/, '');
The base64 issue is likely a red herring. The real problem is usually how you’re handling the request body stream in Node.js before it hits your crypto function. If you’re logging or parsing req.body before signing, the stream might be consumed or modified. The docs state: “The signature is calculated over the raw request body.” You need to capture the raw buffer first. Also, check your client secret. Are you using the one from the Webhook definition or the App credentials? They are different. Here’s a safer pattern using express middleware to capture the raw body without mutation:
app.use(express.json({
verify: (req, res, buf) => {
req.rawBody = buf.toString();
}
}));
// Then in your route
const crypto = require('crypto');
const hmac = crypto.createHmac('sha256', process.env.GENESYS_CLIENT_SECRET)
.update(req.rawBody)
.digest('base64');
if (hmac !== req.headers['x-genesys-signature']) {
return res.status(403).send('Invalid signature');
}
Don’t forget to URL decode the signature header if it contains special characters. The .NET SDK handles this automatically, but raw HTTP requires manual care.
Don’t use the App Client Secret. That’s the trap. The webhook signature is generated using the secret stored specifically in the Webhook definition within Genesys Cloud, not your OAuth app credentials. Mixing them up guarantees a mismatch.
Also, Node.js req.body is often a string by the time you access it. Crypto functions need a Buffer. If you’re passing a string to crypto.createHmac, the byte representation might differ from what Genesys hashed. Force it to a buffer.
const crypto = require('crypto');
// Use the secret from the Webhook definition, NOT the App
const webhookSecret = 'your_webhook_specific_secret';
const signature = req.headers['x-genesys-signature'];
const expected = crypto.createHmac('sha256', webhookSecret)
.update(req.rawBody || req.body) // Ensure you have the raw buffer
.digest('base64');
if (signature !== expected) {
return res.status(401).send('Invalid signature');
}
Check the Webhook config page. Copy the secret directly from there. Paste it into your code. Test again.