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# Secure webhooks
> Authenticate webhook requests using HMAC signatures, Mutual TLS, or OAuth access tokens
Middesk supports three approaches to verify that webhook notifications are authentic and originate from Middesk.
## Verify signatures
Middesk signs webhook requests by including a signature in the `X-Middesk-Signature-256` header. Verify this signature to confirm the request came from Middesk.
> **Warning**
>
> Always verify the HMAC signature against the raw request body before parsing it as JSON. Parsing can alter the byte sequence (encoding changes, JSON reformatting, whitespace trimming), causing signature verification to fail. Only parse verified payloads.
### Set up signature verification
Before you can verify signatures, define a secret using the [Webhooks API](/api-reference/webhooks/create-webhook).
Middesk generates signatures using HMAC with SHA-256.
### Verify the signature in your webhook endpoint
1. Extract the signature from the `X-Middesk-Signature-256` header.
2. Compute an HMAC with SHA-256 using your secret as the key and the raw request body as the message.
3. Compare the header signature to your computed signature using a constant-time comparison method.
```ruby
require 'openssl'
secret = 'sec_...'
def verify(payload, signature)
digest = OpenSSL::Digest.new('sha256')
expected = OpenSSL::HMAC.hexdigest(digest, secret, payload)
OpenSSL.secure_compare(expected, signature)
end
post '/my/webhook/url' do
payload = request.body.read
sig_header = request.env['X_MIDDESK_SIGNATURE_256']
unless verify(payload, sig_header)
# Invalid signature
status 400
return
end
event = JSON.parse(payload)
case event.type
when 'business.created'
business = event.data.object
puts 'Business created!'
when 'business.updated'
business = event.data.object
puts 'Business updated!'
# ... handle other event types
else
# Unexpected event type
status 400
return
end
status 200
end
```
```python
from flask import Flask, request, abort
import hmac
import hashlib
import json
app = Flask(__name__)
secret = 'sec_...'
def verify(payload, signature):
expected = hmac.new(secret, payload, hashlib.sha256).hexdigest()
return hmac.compare_digest(expected, signature)
@app.route('/my/webhook/url', methods=['POST'])
def receive_webhook():
payload = request.data
sig_header = request.headers['X-Middesk-Signature-256']
if not verify(payload, sig_header):
# Invalid signature
abort(400)
event = json.loads(payload)
if event['type'] == 'business.created':
business = event['data']['object']
print('Business created!')
elif event['type'] == 'business.updated':
business = event['data']['object']
print('Business updated!')
# ... handle other event types
else:
# Unexpected event type
abort(400)
return ''
```
```javascript
const bodyParser = require('body-parser');
const crypto = require('crypto');
const express = require('express');
const app = express();
const MIDDLEWARE_WEBHOOK_SECRET = process.env.MIDDESK_WEBHOOK_SECRET;
// Route-specific middleware for raw body parsing with signature verification.
const verifyMiddleware = bodyParser.json({
verify: function(req, res, buf, encoding) {
const signatureHeader = req.get('X-Middesk-Signature-256');
const signature = crypto
.createHmac('sha256', MIDDLEWARE_WEBHOOK_SECRET)
.update(buf)
.digest('hex');
if (signature !== signatureHeader) {
res.status(401).send('Invalid signature.');
throw new Error(`Invalid signature. Got ${signature}. Expected ${signatureHeader}`);
}
}
});
// Apply the verification middleware only to this specific route.
app.post('/my/webhook/url', verifyMiddleware, (req, res) => {
// If here, the signature is valid.
var event = req.body;
switch (event.type) {
case 'business.created':
business = event.data.object;
console.log(`Business ${business.id} created!`);
break;
case 'business.updated':
business = event.data.object;
console.log(`Business ${business.id} updated!`);
break;
// ... handle other event types.
default:
res.status(400).send('Unexpecetd event type');
return;
}
res.status(200)
});
// Start the server
const port = 3000;
app.listen(port, () => {
console.log(`Server running on port ${port}`);
});
```
## Use mutual TLS
The second way to authenticate webhook notifications is to verify Middesk's client certificate during the TLS handshake.
In standard TLS, only the server presents a certificate. With Mutual TLS, the client (Middesk) also presents a certificate. Configure your server to request and verify this client certificate during the TLS handshake.
### Verify Middesk's certificate
Middesk's webhook client certificate is issued by the `DigiCert Assured ID Root G2` Certificate Authority. This CA is configured on most operating systems by default, or you can [download it directly](https://cacerts.digicert.com/DigiCertAssuredIDRootG2.crt.pem).
Verify the client certificate has these Subject Distinguished Name (Subject DN) fields:
```
O=Middesk\, Inc.
CN=webhooks.middesk.com
```
These fields confirm the certificate was issued to Middesk, Inc. and is used for the intended purpose.
### Configure reverse proxies
If you use a reverse proxy for TLS termination, configure it to request and verify the client certificate before routing requests to your backend. Verify the certificate subject matches the fields above before forwarding the request.
## Use OAuth access tokens
A third, but most advanced, mechanism to authenticate webhook notifications is to use OAuth access tokens issued by your OpenID Connect Identity Provider. This method is best for enterprises with complex security requirements.
Use this method if:
* **HMAC shared secrets don't meet your security requirements**. Your organization prohibits sharing secrets externally.
* **Mutual TLS is incompatible with your infrastructure**. Your edge proxies don't support client certificate authentication or make it difficult to relay certificate information to backend applications.
* **You need separation of security responsibilities**. Security teams manage the Identity Provider while application teams focus on token verification.
* **You require precise token scoping**. Tokens can be scoped to specific resource URIs.
* **You must comply with internal governance**. Your organization requires internal IdP-issued tokens for all integrations.
### How OAuth authentication works
Webhook Token Authentication Flow
Middesk Webhook Worker requests an access token from your Identity Provider,
receives the token, then sends the webhook payload with the access token header
to your API.
1\.
Webhook Worker requests
an access token from your
Identity Provider
Client
Your Identity
Provider
Middesk
Webhook Worker
Client
Your API
2\.
Your Identity Provider
responds with access token
3\.
Webhook Worker sends
webhook payload with
access token header
#### Token request
Middesk's webhook worker requests an access token from your Identity Provider (IdP) by sending credentials and the specified scope (your webhook endpoint URI) to the token endpoint.
#### Token issuance
Your Identity Provider validates the credentials and issues a digitally signed access token containing the necessary claims. The webhook worker caches this token for the configured TTL period to reuse for subsequent webhook events.
#### Webhook delivery
The webhook worker sends the request to your API endpoint with the access token in the `Authorization: Bearer {ACCESS_TOKEN}` header. Your endpoint validates the token signature against your IdP's public keys.
Refer to your internal documentation for token validation specifics.
### Set up OAuth authentication
#### Register Middesk with your Identity Provider (IdP)
1. Register an application representing Middesk's webhook worker.
2. Provide Middesk's JWK Set URL: `https://api.middesk.com/v1/webhooks/oidc_keys`
Your IdP uses this URL to validate Middesk's authentication credentials.
3. Save the generated Client ID.
#### Get your IdP's token endpoint URL
Middesk sends token requests to this endpoint.
#### Specify your API resource URI
Provide the URI of your API endpoint that receives webhook events.
Middesk includes this URI in token requests to scope the access token.
#### Define access token time-to-live (TTL)
Set the TTL in seconds for access tokens.
Balance security (shorter TTL) with performance (longer TTL reduces token requests).
Middesk caches tokens for this duration.
#### Configure your API to trust your IdP
1. Set up token validation (typically signature verification using your IdP's JWKS URL).
2. Refer to your internal documentation for validation specifics.
### Configure webhooks to use OAuth
After completing the setup, configure your webhook to use OAuth access tokens via the API. Include these four fields when creating or updating a webhook (currently not available in the Webhooks UI):
| Field | Type | Description |
| :------------------------------ | :------ | :------------------------------------------------------------ |
| `oidc_client_id` | string | Client ID from your Identity Provider registration |
| `oidc_token_endpoint` | string | Token endpoint URL of your Identity Provider |
| `oidc_resource_uri` | string | URI of your API endpoint that receives webhooks |
| `oidc_access_token_ttl_seconds` | integer | Token cache duration in seconds (set to 0 to disable caching) |
## Next steps
#### [Implement webhooks](/build/webhooks)
Set up webhook endpoints to receive real-time event notifications.
#### [Manage API keys](/build/api-keys)
Find, rotate, and use your sandbox and Production API keys.
> **Get a demo**
>
> Contact your account manager or [contact sales](https://www.middesk.com/contact-sales) to inquire about access.