JWT (JSON Web Token) has become the de-facto standard for token-based authentication in modern web applications.
What is JWT?
JWT is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed.
Structure of a JWT
A JWT consists of three parts separated by dots (.):
- Header: Specifies the token type and the hashing algorithm.
- Payload: Contains the claims, which are statements about an entity (typically, the user) and additional data.
- Signature: Used to verify the message wasn't changed along the way.
Security Best Practices
- Use strong algorithms: Always prefer RS256 or HS256. Avoid the "none" algorithm.
- Set expiration times: Tokens should always expire to minimize risk if a token is stolen.
- Store securely: Use httpOnly cookies to prevent XSS attacks from stealing tokens.
Conclusion
JWT is a powerful tool when used correctly. Understand the security implications and always validate your tokens on the server side.