Metamask Validation: Securely Verifying Signed Messages in C

Applications

As a developer working with blockchain technology, you are probably familiar with the importance of secure communication and data integrity. In this article, we will explore how to validate signed messages from a C

application backend using Metamask.

What is Metamask?

Metamask is a popular browser extension that allows users to interact with web3 platforms, including Ethereum, without requiring an internet connection. It allows developers to build decentralized applications (dApps) and access various blockchain features through its API.

Verifying Signed Messages with Metamask in C#

When developing a single-page application using C#, you can use the WebAssembly (WASM) module from MetaMask to validate signed messages. This approach offers several advantages, including:

• Decoupling: The WASM module is not tightly coupled to the underlying browser environment, allowing for more flexibility and control.

• Security: Using a separate module, you can ensure that your C
  

  application remains secure even if the MetaMask API is compromised or blocked.

Here is an example of how to validate signed messages from a C

backend:

using System;
using System.Web.Http;
// Define a custom message signing and validation function
public static class MessageSigner
{
public static (String, String) SignMessage(String message)
{
// Replace your message signing logic
// For demonstration purposes, we will use a simple HMAC method
var key = "YOUR_SECRET_KEY";
var hmac = new HMACSHA256(key);
var signature = hmac.ComputeHash(Encoding.UTF8.GetBytes(message));
return (signature, BitConverter.ToString(signature).Replace("-", ""));
}
public static string VerifySignature(string message, string signature)
{
// Change your validation logic
// For demonstration purposes, we will use a simple digital signature validation method
var key = "YOUR_SECRET_KEY";
var hmac = new HMACSHA256(key);
return hmac.ComputeHash(Encoding.UTF8.GetBytes(message)) == Encoding.UTF8.GetBytes(signature);
}
}
// Define a controller action that validates signed messages
[HttpPost]
public class SignedMessageValidator : HttpResponseBase
{
[HttpPost("validate")]
public bool ValidateSignedMessage(string message, string signature)
{
// Extract the signed message from the request body
var signedMessage = MessageSigner.SignMessage(message);
// Verify the signed message using the Metamask API
if (MessageSigner.VerifySignature(signedMessage.Item1, signedMessage.Item2))
{
return true;
}
else
{
return false;
}
}
}

Sample use case

To test the SignedMessageValidator action of the controller, you can use a tool like Postman or cURL. Here is a sample request:

”bash

POST /validate HTTP/1.1

Content-type: application/json

{

“message”: “Custom signed message”

}

“`

If the signed message is valid, the server will respond with a success status code, otherwise a failure status code.

Conclusion

By using the Metamask WASM module to validate signed messages in your C

applications, you can ensure secure communication and data integrity. This approach is a flexible and decoupled way to build decentralized applications, allowing developers to focus on building innovative blockchain features without worrying about infrastructure complexity.

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