Requirements

The core challenge is to design a robust and extensible Authentication and Authorization service. This service needs to support multiple authentication methods (like username/password, OTP, OAuth) and provide a flexible authorization mechanism to control access to resources. This requires a well-defined class structure, adherence to SOLID principles, and proper handling of concurrency. The service should be designed to accommodate new authentication methods and authorization policies without requiring significant code changes. Imagine you are building a security layer for a sophisticated platform where different clients need different authentication and authorization workflows. # Requirements ## Functional Requirements 1. **User Registration:** * Allow new users to register with a username and password. * Support additional user attributes during registration (e.g., email, phone number). * Implement password strength validation. 2. **Authentication:** * Support username/password authentication. * Implement One-Time Password (OTP) authentication (e.g., via email or SMS). * Integrate with OAuth 2.0 providers (e.g., Google, Facebook). * Support for multi-factor authentication (MFA) combining multiple authentication methods. * Handle authentication failures gracefully (e.g., account lockout after multiple failed attempts). 3. **Authorization:** * Implement role-based access control (RBAC). * Allow defining permissions for roles. * Support assigning roles to users. * Provide a mechanism to check if a user has permission to access a specific resource. * Support attribute-based access control (ABAC) for more granular authorization (optional, but consider the design implications). 4. **Session Management:** * Create and manage user sessions after successful authentication. * Implement session timeout and renewal mechanisms. * Provide a way to invalidate sessions (e.g., logout functionality). * Consider storing session data securely (e.g., using HTTP-only cookies). 5. **Account Management:** * Allow users to update their profile information (e.g., password, email, phone number). * Implement password reset functionality. * Support account deletion. 6. **Audit Logging:** * Log all authentication and authorization attempts, including successes and failures. * Include relevant information in the logs (e.g., timestamp, user ID, IP address, resource accessed). ## Non-Functional Requirements 1. **Security:** * Protect against common security vulnerabilities (e.g., SQL injection, cross-site scripting). * Store passwords securely (e.g., using a strong hashing algorithm with salting). * Protect against brute-force attacks. * Ensure that session data is encrypted and protected from unauthorized access. 2. **Extensibility:** * The system should be easily extensible to support new authentication methods and authorization policies. * New user attributes should be able to be added without modifying core components. 3. **Modularity:** * The system should be modular, with well-defined components and interfaces. * Each component should have a clear responsibility and be loosely coupled with other components. 4. **Testability:** * The system should be designed to be easily testable, with unit tests for individual components and integration tests for interactions between components. * Consider using dependency injection to facilitate testing. 5. **Thread Safety:** * The service must be thread-safe, as it will likely be accessed by multiple concurrent requests. Carefully consider synchronization and thread-local variables. 6. **Performance:** * Authentication and authorization checks should be performed efficiently. * Consider caching frequently accessed data (e.g., user roles, permissions) to improve performance. The *class design* should facilitate plugging in caching. ## Core Entities 1. **User:** Represents a user of the system. Contains attributes such as username, password hash, email, phone number, roles, and potentially custom attributes. 2. **AuthenticationProvider:** An interface or abstract class that defines the contract for authentication methods. Implementations include UsernamePasswordAuthProvider, OTPAuthProvider, and OAuthProvider. Uses the Strategy Pattern. 3. **Authenticator:** Responsible for coordinating the authentication process, selecting the appropriate AuthenticationProvider, and managing user sessions. 4. **AuthorizationPolicy:** An interface or abstract class that defines the contract for authorization policies. Implementations could include RoleBasedPolicy and AttributeBasedPolicy. Uses the Strategy Pattern. 5. **Authorizer:** Responsible for evaluating authorization policies and determining whether a user has access to a resource. 6. **Role:** Represents a role in the system. Contains a list of permissions. 7. **Permission:** Represents a permission that can be assigned to a role. 8. **Session:** Represents a user session. Contains information about the user, session creation time, and expiration time. 9. **Resource:** Represents a resource that needs to be protected by authorization. This might be implicit in the code using annotations. 10. **AuditLogger:** Component responsible for logging all authentication and authorization events.

Design Authentication/Authorization Service which supports(otp,OAuth, etc.).

Requirements

Interview Simulation

Functional Requirements

💡 Interview Tip

Non-Functional Requirements

Core Entity Identification

Premium Content