# HMAC Signature Validator MCP for AI Agents AI Agent Connect

> HMAC Signature Validator MCP provides high-precision cryptographic tools for generating and verifying HMAC signatures. It uses constant-time comparison to protect against timing attacks, supporting SHA256 and SHA1 algorithms for secure message authentication and data integrity.

## Overview
- **Category:** security
- **Price:** Free
- **Endpoint:** https://edge.vinkius.com/vk_preview_gWGMvzG4iAvT97lHqBpehck0DefoznivwVASd4tU/ai-agent-connect
- **Tags:** hmac, sha256, sha1, security, cryptography

## Description

This MCP gives your AI agent the ability to handle sensitive cryptographic tasks without you having to manually write math-heavy code. Instead of you jumping into a terminal to run scripts, your agent can now generate secure signatures or verify incoming webhooks and data packets on the fly. It handles the heavy lifting of constant-time comparison, which is a critical security measure to prevent timing attacks that could leak your secret keys. Whether you are testing API security or validating data integrity in a production pipeline, this tool makes it a standard part of your agent's toolkit. By connecting through Vinkius, you get a reliable way to add professional-grade signature verification to your existing workflows without managing complex local dependencies.

## Tools

### compute_hmac
Calculates an HMAC signature for a message using SHA256 or SHA1. It's perfect for generating signatures to test API authentication.

### get_supported_algorithms
Lists the cryptographic algorithms available for signing and verification. Use this to confirm which hashing method to use.

### verify_hmac_signature
Validates a signature against a message and key using secure constant-time comparison. This prevents timing attacks during verification.

## Prompt Examples

**Prompt:** 
```
Can you generate an HMAC SHA256 signature for the message 'order_id:12345' using the key 'super-secret-key'?
```

**Response:** 
```
Here is the HMAC SHA256 signature for your message:

**Message:** `order_id:12345`  
**Algorithm:** `SHA256`  
**Signature:** `e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855`
```

**Prompt:** 
```
I have a signature 'abc123def' for the message 'test_data' with key 'key123'. Is it valid using sha256?
```

**Response:** 
```
I've checked the signature against your message and key.

| Parameter | Value |
| :--- | :--- |
| **Status** | ❌ **Invalid** |
| **Message** | `test_data` |
| **Algorithm** | `SHA256` |
```

**Prompt:** 
```
What cryptographic algorithms can you use to sign messages?
```

**Response:** 
```
I can currently use the following algorithms for HMAC operations:

* **SHA256** (Recommended for most modern security needs)
* **SHA1** (For legacy system compatibility)
```

## Capabilities

### Generate secure signatures
Create HMAC signatures for any message using SHA256 or SHA1 algorithms.

### Verify message authenticity
Check if a signature is valid for a specific message and key using secure comparison.

### Prevent timing attacks
Use constant-time comparison to ensure signature verification doesn't leak sensitive timing data.

### Check available algorithms
Identify which cryptographic hashing methods are ready for use.

## Use Cases

### Webhook security testing
A developer needs to ensure their server correctly validates GitHub webhooks. They ask their agent to generate a signature with compute_hmac to simulate a real request.

### API authentication debugging
An engineer is getting 401 errors on an API. They use verify_hmac_signature to check if their local signature matches what the server expects.

### Data integrity audits
A security analyst uses the MCP to verify that a batch of transmitted logs hasn't been tampered with by checking their HMAC signatures.

### Automated security testing
A DevOps engineer builds a workflow where the agent automatically verifies the authenticity of configuration files using SHA256 signatures.

## Benefits

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## How It Works

The bottom line is you get professional-grade cryptographic verification directly inside your chat interface.

1. Connect the MCP to your AI client via the Vinkius catalog.
2. Provide your agent with the message, the secret key, and the desired algorithm.
3. Receive a verified result or a newly generated signature immediately.

## Frequently Asked Questions

**How can I use the HMAC Signature Validator MCP to test my webhooks?**
You can ask your agent to generate a valid signature for a specific payload using the compute_hmac tool. You then use that signature to simulate a real request from a service like GitHub or Stripe to see if your server accepts it.

**Does the HMAC Signature Validator MCP protect against timing attacks?**
Yes. The verify_hmac_signature tool uses constant-time comparison, which ensures that the time taken to validate a signature doesn't reveal information about the correct signature to an attacker.

**Can I use this MCP with Claude or Cursor?**
Yes, as long as you are using an MCP-compatible client like Claude, Cursor, or Windsurf, you can connect this MCP and use it immediately.

**What algorithms does the HMAC Signature Validator MCP support?**
The MCP currently supports SHA256 and SHA1 algorithms for both generating and verifying HMAC signatures.

**Is it possible to verify a signature if I don't know the algorithm used?**
You should first use the tool to check which algorithms are supported, then attempt verification with the most likely algorithm (usually SHA256) to see if it matches.

**What algorithms are supported?**
The server supports SHA256 and SHA1 algorithms. You can use `get_supported_algorithms` to confirm availability.

**How does this prevent timing attacks?**
The `verify_hmac_signature` tool uses constant-time comparison, ensuring the verification time remains identical regardless of whether the signature is correct or where a mismatch occurs.

**Can I generate new signatures?**
Yes, you can use the `compute_hmac` tool to generate a hexadecimal HMAC signature for any message and secret key.