Authentication and data security are at the core of modern web applications. In this post, we’ll explore important concepts like public & private key cryptography, stateless vs state full systems, JWT structure, secure storage practices, and token invalidation.
1. Public & Private Key Cryptography
Public and private key cryptography, also known as asymmetric encryption, secures data transmission using a pair of keys:
Public Key: Shared openly and used to encrypt data.
Private Key: Kept secret and used to decrypt data.
How It Works: The sender encrypts the data with the recipient's public key. Only the recipient with the private key can decrypt the data. Used in SSL certificates, email encryption, digital signatures.
2. Stateless vs State full Systems
Authentication systems can be either stateless or state full.
Stateless Systems: No session storage on the server. Each request is self-contained, usually with tokens like JWT. Easier to scale horizontally.
State full Systems: Requires server-side session storage. Relies on session IDs stored in cookies. More secure but less scalable without extra infrastructure.
3. What is JWT (JSON Web Token)?
JSON Web Tokens are an open, industry standard RFC 7519 method for representing claims securely between two parties.
4. How is a JWT Structured?
A JWT has three parts:
Header: Specifies the token type (JWT) and hashing algorithm.
Payload: Contains claims (user data, roles, expiration). This is not encrypted.
Signature: Verifies the token’s authenticity.
5. How Can You Invalidate a JWT?
JWTs are stateless and cannot be invalidated server-side by default, but there are workarounds:
Token Invalidation Strategies:
Expiration Claims: Set a reasonable expiration time (exp claim).
Revocation Lists: Maintain a blacklist of invalidated tokens.
Token Rotation: Use refresh tokens with short-lived access tokens.
Forced Logout: Change the secret key or revoke tokens after sensitive operations.
Final Thoughts:
Understanding cryptography, stateless systems, and JWT security practices is crucial for building secure backend systems. Let me know your thoughts, feedback, or additional insights in the comments!
Resource: https://jwt.io/
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