JWT (JSON Web Token) is a popular way to implement secure authentication in modern web applications. It provides a lightweight and stateless mechanism to authenticate users, ensuring secure data transfer. In this blog post, we’ll explore how to implement JWT authentication in a C# ASP.NET Core application with a step-by-step example.
What is JWT?
A JWT is a token that is used to securely transmit information between two parties (client and server). It is digitally signed, ensuring that the data it contains can be trusted. JWT consists of three parts:
- Header: Specifies the algorithm used to generate the signature, typically HMAC SHA256 or RSA.
- Payload: Contains the claims or the data being transmitted (such as user ID, roles, etc.).
- Signature: Ensures that the token hasn’t been tampered with.
The general structure looks like this:
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1bmlxdWVfbmFtZSI6InVzZXIwMSIsIm5iZiI6MTczMTIxMDQ4OCwiZXhwIjoxNzMxMjExNjg4LCJpYXQiOjE3MzEyMTA0ODh9.2adOgvFCgF4FfzwWS3VbT-AOUvXvwwMmI76HrdTXFW4
Why JWT?
- Stateless: No need to store sessions on the server.
- Scalable: The server doesn’t need to store or retrieve session information.
- Cross-domain: JWT can be easily used across different domains, making it ideal for distributed applications like microservices.
