Verifying Genesys Cloud webhook signatures in Node.js

NICE CXone API & Integrations
1

Trying to understand the signature verification logic for inbound webhooks.

we’re moving IVR logic to GC and need to stop replay attacks on our endpoint. the docs mention X-Genesys-Request-Signature but i’m stuck on the payload hashing. here’s what i have so far:

const crypto = require('crypto');
const sig = req.headers['x-genesys-request-signature'];
const body = req.rawBody; // or req.body?
const algo = 'sha256';
const hmac = crypto.createHmac(algo, secretKey);
hmac.update(body);
const calculated = hmac.digest('hex');

if i use the raw string body it fails. does GC hash the JSON stringified version or the raw buffer? also is there a timestamp check i’m missing to prevent replay?

2

check your crypto setup. you need sha256. here’s the flow:

  • grab the raw body (not parsed).
  • create an hmac with your shared secret.
  • update with the raw body.
  • digest to hex.

compare that against x-genesys-request-signature. if it doesn’t match, reject it. simple.

3 
const hmac = crypto.createHmac('sha256', process.env.GENESYS_WEBHOOK_SECRET);
const digest = hmac.update(req.rawBody).digest('hex');

The easiest way to fix this is to use sha256 on the raw buffer. make sure you’re not parsing the json before signing or the hash won’t match.