Does anyone know the exact algorithm for verifying the X-Genesys-Signature header in a Node.js webhook consumer? I am building a secure endpoint to ingest v2.analytics.conversation.aggregate events and need to validate the payload integrity before processing. The documentation mentions HMAC-SHA256, but I am unsure if the secret key should be the OAuth client secret or a specific webhook secret generated in the UI. My current implementation uses crypto.createHmac('sha256', secret).update(payload).digest('hex'), but the computed signature never matches the header value.
I have confirmed that the payload string is the raw POST body, not the parsed JSON object, and I am handling the newline characters correctly. However, I consistently get a mismatch error. Is there a specific encoding requirement for the secret key, or should I be including the timestamp in the signature calculation? I want to ensure this is robust against replay attacks, so I need to verify the signature before checking the event timestamp against a sliding window.
It depends, but generally… you want to ensure the secret matches the webhook configuration exactly. I handle this in my Rails middleware using Faraday and Sidekiq for async processing. Here is the step-by-step verification logic:
Extract the X-Genesys-Signature header and the raw request body.
Use the specific webhook secret from Genesys Admin, not the OAuth client secret.
have you tried using the specific webhook secret from the ui? i usually see people confuse this with the oauth client secret which fails immediately. also ensure you are hashing the raw buffer, not a stringified body. node mutates req.body often. check the signature against the raw stream.
Have you tried isolating the raw request body before any middleware parsing occurs?
Does anyone know the exact algorithm for verifying the X-Genesys-Signature header in a Node.js webhook consumer?
The core issue is not the algorithm itself, but the input data. The X-Genesys-Signature is an HMAC-SHA256 hash of the raw HTTP body. If you use standard body parsers like express.json() or body-parser, the buffer is converted to a string or object. The hash of that transformed data will never match the signature calculated on the raw stream.
You must access the raw buffer directly. In a standard Express setup, you can bypass the JSON parser for this specific route or capture the raw body in middleware. The secret key is indeed the Webhook Secret found in the Genesys Cloud Admin UI under the specific webhook configuration, not your OAuth Client Secret.
Here is a working implementation using express and crypto:
const crypto = require('crypto');
// Middleware to capture raw body
app.use('/webhooks/genesys', express.raw({ type: 'application/json' }), (req, res, next) => {
const rawBody = req.body;
const signature = req.headers['x-genesys-signature'];
const webhookSecret = process.env.WEBHOOK_SECRET; // From Genesys UI
// Calculate HMAC-SHA256
const hmac = crypto.createHmac('sha256', webhookSecret);
const digest = hmac.update(rawBody).digest('hex');
// Secure comparison to prevent timing attacks
const isValid = crypto.timingSafeEqual(
Buffer.from(signature, 'hex'),
Buffer.from(digest, 'hex')
);
if (!isValid) {
return res.status(401).send('Invalid signature');
}
// Parse JSON manually since we used raw()
const payload = JSON.parse(rawBody.toString());
// Process payload
console.log('Valid event received:', payload.eventName);
res.status(200).send();
});
Ensure your environment variable WEBHOOK_SECRET matches the key generated in the Genesys Cloud Admin portal. If the signature still fails, log the raw buffer length and the calculated digest to verify the input stream is not being truncated by network proxies.