Authentication and authorization form the security foundation for modern applications. OAuth 2.0 provides standard flows for delegated authorization. JWTs enable stateless authentication across distributed services. However, common implementation mistakes create security vulnerabilities. Understanding best practices and common pitfalls guides secure authentication system design.
OAuth 2.0 Flow Selection
Different OAuth flows suit different application types. Authorization Code with PKCE secures single-page and mobile applications. Client Credentials enable service-to-service authentication. Refresh tokens provide long-lived access without credential reentry. Selecting appropriate flows balances security with user experience for specific application architectures.
- Use Authorization Code flow with PKCE for browser and mobile applications
- Implement short-lived access tokens with refresh token rotation
- Validate JWT signatures and claims before trusting token content
- Store tokens securely using httpOnly cookies or secure storage APIs
- Implement proper logout handling invalidating tokens server-side when possible
JWT Security Considerations
JWT tokens require careful handling preventing common vulnerabilities. Signature verification ensures token authenticity. Expiration checking prevents indefinite token validity. Audience and issuer validation confirms tokens target your application. Claim validation ensures expected values. These checks prevent token-based attacks.
Authorization Patterns
Authorization determines what authenticated users can do. Role-based access control (RBAC) assigns permissions through roles. Attribute-based access control (ABAC) makes decisions using user attributes and context. Resource-based permissions provide fine-grained control. Choosing appropriate patterns depends on application requirements and organizational structure.