Authentication, Authorization, and Credential Mechanisms: Cookies, Sessions, Tokens, and JWT

Authentication, Authorization, and Credentials

Authentication verifies a user's identity (e.g., password login, email link, SMS code), while authorization determines what actions an authenticated user may perform. Credentials are the media (e.g., ID cards, tokens) that prove identity.

Cookies and Sessions

HTTP is stateless, so servers use cookies or sessions to track users. Cookies are stored client‑side and sent with each request; they are domain‑bound and limited to ~4 KB. Sessions store state server‑side, with the session ID kept in a cookie. Session data can be shared via replication, sticky routing, or external stores such as Redis.

Token‑Based Authentication

Tokens (e.g., JWT) are issued after successful login and stored client‑side (often in localStorage). Each request includes the token in the Authorization: Bearer <token> header, allowing stateless verification without server‑side session storage.

Authorization: Bearer <token>

JWT Overview

JWT consists of a header (algorithm), payload (claims such as user ID and expiration), and signature. It is self‑contained, enabling cross‑domain authentication without cookies. Validation involves recomputing the signature with the server’s secret key.

GET /calendar/v1/events

JWTs can be transmitted via headers, request bodies, or query parameters (e.g., http://www.example.com/user?token=xxx ).

http://www.example.com/user?token=xxx

Common Authentication Methods

Session‑Cookie

Token verification (including JWT and SSO)

OAuth 2.0

Security Considerations

Cookies are vulnerable to tampering; use HttpOnly and limit size.

Sessions consume server memory; sharing across nodes requires external stores.

Tokens can be long and may expose data if stored insecurely; prefer short lifetimes and HTTPS.

JWTs are not encrypted by default; avoid placing sensitive data in payloads.

Distributed Session Sharing Strategies

Session replication across nodes.

Sticky sessions (IP‑hash routing).

External session stores (Redis, Memcached) for shared access.

Persisting sessions in databases for durability.

Practical Tips

Never store passwords in plain text; always hash with strong algorithms.

Use HTTPS to protect token transmission.

Implement token revocation via blacklists if needed.