Choosing the Right Temporary Data Storage: JWTs versus Server-Side Sessions

When developing authentication workflows, especially those involving temporary data like verification tokens or user details pending validation, selecting an appropriate storage mechanism is crucial. The challenge often lies in balancing security, performance, and implementation complexity.

Use Case Overview

Suppose you need to temporarily store user information such as username, email, hashed password, and a one-time password (OTP) until the user verifies their OTP. A common approach involves generating a unique token, associating it with a timestamp stored in a database, and then referencing this token via short-lived cookies (e.g., five-minute expiry). However, this method typically necessitates regular database cleanup to remove expired tokens, which can increase server load due to frequent scheduled maintenance tasks.

Alternative Approaches: JWTs and Encrypted Cookies

One suggested alternative is to store the temporary data directly on the client side as encrypted cookies, avoiding database cleanup altogether. Conversely, JSON Web Tokens (JWTs) provide a self-contained way to carry user data securely.

Understanding the Options

1. Server-Side Sessions and Database Storage:
2. Advantages: Centralized control, easier to invalidate tokens, familiar for many developers.

3. Disadvantages: Requires regular cleanup of expired records, which may increase database and CPU load, especially with high traffic.

4. JWTs (JSON Web Tokens):

5. Advantages: Self-contained tokens that encode user data, eliminating the need for database lookups for each request.

6. Disadvantages: Once issued, JWTs cannot be revoked until expiration; sensitive data should be encrypted or minimized.

7. Encrypted Cookies (Client-Side Storage):

8. Advantages: Reduce server load by offloading data storage to the client; no cleanup needed on the server side.
9. Disadvantages: Increased reliance on secure, correctly implemented encryption; potential security risks if not properly handled.

Best Practices and Recommendations

• For Short-Lived Data:
  When data such as OTP verification information is only needed briefly, consider using encrypted cookies with appropriate security measures—such as HttpOnly, Secure, and SameSite flags. This approach allows the client to hold necessary metadata without burdening the server with cleanup tasks.

• For Data Requiring Strong Server Control:
  If you prefer server-side control and easier invalidation, implementing short-lived JWTs is efficient. You can generate a JWT with