C++ Authentication API

Introduction to JWT in C++

JSON Web Tokens (JWT) provide a compact, URL-safe way to represent claims between two parties. In the context of C++, JWTs are commonly used to authenticate users and provide secure access to endpoints.

This tutorial demonstrates how to implement JWT-based authentication in a C++ application, using a practical example.

Setting Up the Environment

Before diving into code, ensure you have a suitable development environment set up. You'll need:

• A C++ compiler (e.g., g++)
• CMake for building the project
• The jwt-cpp library for handling JWTs
• OpenSSL for cryptographic operations

Installing Dependencies

To get started, install the necessary libraries using a package manager. For instance, on Ubuntu, you can use:

sudo apt-get update
sudo apt-get install libssl-dev cmake

Integrating jwt-cpp into Your Project

The jwt-cpp library is a lightweight C++ library for creating and verifying JWTs. You can add it to your project by cloning its repository:

git clone https://github.com/Thalhammer/jwt-cpp.git

Generating JWTs in C++

JWTs consist of three parts: header, payload, and signature. Here's how you can generate a JWT in C++:

#include <jwt-cpp/jwt.h>

std::string create_jwt() {
    auto token = jwt::create()
        .set_issuer("auth0")
        .set_type("JWS")
        .set_payload_claim("sample", jwt::claim(std::string("data")))
        .sign(jwt::algorithm::hs256{"secret"});
    return token;
}

int main() {
    std::string token = create_jwt();
    std::cout << "Generated JWT: " << token << std::endl;
    return 0;
}

Validating JWTs in C++

To validate a JWT, you must verify its signature and ensure the claims are as expected. Here's an example of validating a JWT:

#include <jwt-cpp/jwt.h>

void validate_jwt(const std::string& token) {
    auto decoded_token = jwt::decode(token);
    auto verifier = jwt::verify()
        .allow_algorithm(jwt::algorithm::hs256{"secret"})
        .with_issuer("auth0");
    verifier.verify(decoded_token);
    std::cout << "JWT is valid." << std::endl;
}

int main() {
    std::string token = create_jwt();
    validate_jwt(token);
    return 0;
}

Conclusion

In this tutorial, you learned how to integrate JWT authentication into a C++ application. By following these steps, you can ensure secure access to your application's endpoints.

Continue to the next post in this series to learn about implementing Database CRUD operations in C++.