Authentication Mechanism

About

Authentication is the process of verifying the identity of a user, system, or application. Spring Security provides multiple authentication mechanisms, allowing developers to integrate various authentication methods based on security requirements.

Authentication Flow

Regardless of the mechanism used, authentication follows a general flow:

1. User Requests Access

   • The user or client sends a request to the secured resource (e.g., login form, API request).

2. Authentication Attempt

   • Credentials (username/password, token, etc.) are submitted to the authentication mechanism.

3. Verification Process

   • The authentication mechanism (e.g., AuthenticationManager) verifies credentials using AuthenticationProvider.

   • If successful, an Authentication object is created.

4. Security Context Update

   • The verified authentication details are stored in SecurityContextHolder for future requests.

5. Authorization Check

   • The application verifies if the authenticated user has sufficient GrantedAuthority to access the requested resource.

6. Access Granted or Denied

   • If the user has the correct permissions, access is granted. Otherwise, access is denied.

Types of Authentication Mechanisms

Authentication mechanisms can be categorized into the following types:

Category	Mechanism
Basic Authentication	Username/Password (Form Login, Basic Auth, Digest Auth)
Token-Based Authentication	JWT (JSON Web Token), OAuth2, API Keys
Multi-Factor Authentication (MFA)	OTP (One-Time Password), Authenticator Apps
Federated Authentication	SAML, OpenID Connect (OIDC), Social Logins (Google, Facebook, GitHub)
Biometric Authentication	Fingerprint, Face Recognition
Certificate-Based Authentication	X.509 Certificates
Session-Based Authentication	HTTP Session Cookies, Remember-Me