# Webhook HMAC Signature Validator MCP for AI Agents MCP

> Webhook HMAC Signature Validator ensures your incoming webhooks are real and haven't been tampered with. It lets your AI agents verify signatures using secret keys, parse complex header strings, and fetch provider secrets to stop spoofing attacks before they hit your automation pipeline.

## Overview
- **Category:** security
- **Price:** Free
- **Endpoint:** https://edge.vinkius.com/undefined/mcp
- **Tags:** hmac, webhook, security, sha256, validation

## Description

If you are running automations that trigger based on Stripe or GitHub events, you know how risky unverified webhooks can be. A single fake request could trigger unauthorized actions or mess up your production data. This MCP acts as a security gate for your agent. It lets you check if the math behind a request actually matches your secret keys. You can pull those keys through Vinkius and have your agent break down messy header strings without you doing any manual work. It is about making sure your automation only reacts to real, untampered events. By using constant-time comparisons, it even protects you from timing attacks that try to guess your secrets.

## Tools

### validate_webhook_signature
Checks if a payload matches its signature and secret key. This prevents unauthorized requests from being processed.

### decompose_header_string
Splits a webhook header into the algorithm and signature parts. It handles complex formats like sha256 prefixes easily.

### fetch_provider_secrets
Grabs the necessary secret keys for your integrations. This keeps your verification process automated and secure.

## Prompt Examples

**Prompt:** 
```
I just got a webhook from Stripe. Can you check if this payload is legit?
```

**Response:** 
```
| Component | Value |
| :--- | :--- |
| **Payload** | `{ "id": "evt_123", "type": "payment_intent.succeeded" }` |
| **Signature** | `t=1625... ,v1=7f83b1...` |
| **Status** | **Verified Authentic** |
```

**Prompt:** 
```
What is inside this header string: 'sha256=7f83b1...'?
```

**Response:** 
```
The header contains two parts:

* **Algorithm:** `sha256` 
* **Signature:** `7f83b1...`
```

**Prompt:** 
```
How do I verify a GitHub webhook using my stored secrets?
```

**Response:** 
```
Follow these steps:
1. Use the tool to fetch your GitHub secret.
2. Pass the raw request body and the signature header to the validation tool.
3. The agent will confirm if the signatures match.
```

## Capabilities

### Verify payload authenticity
Check if an incoming request is legitimate by matching the payload against its signature.

### Parse complex webhook headers
Break down messy header strings into usable algorithm and signature components.

### Retrieve integration secrets
Automatically pull the necessary keys for your specific service providers.

### Prevent timing attacks
Use secure comparison methods to ensure attackers cannot guess your secret keys.

## Use Cases

### Verifying Stripe payments
A developer receives a payment notification and needs to confirm it is actually from Stripe before fulfilling an order.

### Securing GitHub actions
An automation script triggers on repository updates, but you need to verify the payload signature first.

### Security auditing
You are reviewing your webhook logs and want to check if any recent requests failed signature validation.

### New integration setup
Setting up a new Slack integration where you need to parse the incoming header format to extract the signature.

## Benefits

- Stop spoofing attacks by ensuring every incoming request is legitimate.
- Automate secret management using fetch_provider_screts so you do not have to hardcode keys.
- Simplify header parsing with decompose_header_string to handle messy string formats instantly.
- Protect your automation logic from unauthorized triggers via validate_webhook_signature.
- Reduce manual debugging time when verifying third-party event deliveries.

## How It Works

The bottom line is you stop spoofed webhooks from triggering unauthorized actions in your automation.

1. Connect your preferred AI client to the Vinkius catalog.
2. Provide the webhook payload and header string to your agent.
3. The agent verifies the signature against the retrieved secret and confirms authenticity.

## Frequently Asked Questions

**How can I prevent fake webhooks with Webhook HMAC Signature Validator?**
It verifies that incoming payloads match their original signatures using trusted secrets, so spoofed requests are rejected immediately.

**Does Webhook HMAC Signature Validator work with Stripe?**
Yes, it is designed to handle standard provider formats like Stripe by fetching the necessary keys and validating the signature.

**Can I use Webhook HMAC Signature Validator for any service?**
Any service that uses HMAC signatures in their webhook headers can be secured using this MCP.

**How does Webhook HMAC Signature Validator handle complex headers?**
It includes a specific tool to break down complicated header strings into the algorithm and signature components for easy processing.

**Is Webhook HMAC Signature Validator secure against timing attacks?**
Yes, it uses constant-time comparison logic to ensure that attackers cannot use response times to guess your secret keys.