# Validation and versioning of payloads

## Validating payloads

All transports sent to your webhooks have a `X-Hub-Signature` header, which contains the hash signature for the transport. The signature is a HMAC hexdigest of the request body, generated using sha256 and your `secret` as the HMAC key.

You could use a function in Node.JS such as the following to validate these signatures on incoming requests from Snyk:

```
import * as crypto from 'crypto';

function verifySignature(request, secret) {
  const hmac = crypto.createHmac('sha256', secret);
  const buffer = JSON.stringify(request.body);
  hmac.update(buffer, 'utf8');

  const signature = `sha256=${hmac.digest('hex')}`;

  return signature === request.headers['x-hub-signature'];
}
```

## Payload versioning

Payloads may evolve over time, and so are versioned. Payload versions are supplied as a suffix to the `X-Snyk-Event` header. For example, `project_snapshot/v0` indicates that the payload is `v0` of the `project_snapshot` event.

Version numbers only increment when a breaking change is made, for example, removing a field that used to exist, or changing the name of a field. Version numbers do not increment when making an additive change, such as adding a new field that never existed before.

{% hint style="warning" %}
During the BETA phase, the structure of webhook payloads may change at any time, so Snyk recommends that you check the payload version.
{% endhint %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.snyk.io/developer-tools/snyk-api/using-specific-snyk-apis/webhooks-apis/validation-and-versioning-of-payloads.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.