JSON Web Tokens (JWT) have become a staple in modern web authentication. In this article, we will explore the practical steps to learn JWT by reverse engineering, using a demo that allows you to dive into its concepts hands-on.

How To Use It

• First, visit the demo hosted on repl.it.
• If you prefer to run it on your local machine, you can clone the repository and execute the following commands:

bash
# Install dependencies
npm install

# Create environment variables file
cp ENV_SAMPLE .env

# Run your application
npm start

• Defaults should work for local setups, but for production, ensure to set environment variables for your server, like API_URL and FRONTEND_URL.
• Finally, navigate to localhost:3000 in your browser to test the application.

Once you’re in, play around with the configurations and read the cues on each page for additional resources to deepen your understanding!

Understanding the Code: An Analogy

Imagine creating a secret recipe book, where each recipe follows a special format that only you and your friends understand. In our context, JWTs are like those recipes. Each token is a recipe card that has specific ingredients (data) and instructions (signature) ensuring that what you’ve written is authentic and hasn’t been tampered with.

When you install dependencies and set environment variables, you’re ensuring that your kitchen (your development environment) is prepared with all the tools (libraries and settings) to cook up your JWT recipe correctly. Finally, when you serve the dish (run the application), each tester (client) can see if the recipe (token) holds true according to the defined rules.

Troubleshooting

If you find yourself running into issues while setting up or using the demo, consider the following troubleshooting tips:

• Ensure you have Node.js and npm installed on your machine.
• Double-check the .env file to make sure all necessary environment variables are correctly set.
• Try restarting your server if you encounter unexpected behavior.

For more insights, updates, or to collaborate on AI development projects, stay connected with fxis.ai.

Documentation

If you want to extend the code for additional functionalities, make sure to check out the documentation.

References

About Tokens

• JWT
• JWT vs Opaque tokens

Cryptography

• Asymmetric Cryptography
• Digital Signatures
• Forward Secrecy
• Encryption vs Signing
• Encryption vs Encoding
• Hashing vs Encoding vs Encryption vs Obfuscation

Invalidating JWT

• Strategies to invalidate JWT
• Discussion: Refreshing an expired JWT token

Security Risks

• JWT attack – signature as MAC
• Recreating JWT validation bypass
• 3 JWT design flaws

Implementations (Examples and Demos)

• Demo: Docusign APIs auth workflow with JWT
• JWT Authentication in NodeJs
• JWT+Passport
• JWT+Passport: Code
• JWT+Passport: Guide on DigitalOcean
• Passport-jwt
• Refreshing token using node-jsonwebtoken

Other Useful Tools

• Encode or Decode JWTs

At fxis.ai, we believe that such advancements are crucial for the future of AI, as they enable more comprehensive and effective solutions. Our team is continually exploring new methodologies to push the envelope in artificial intelligence, ensuring that our clients benefit from the latest technological innovations.