Question

You have been asked to design a secure system that requires strong authentication and authorization. The system must be designed so that communications between parts of the system cannot be intercepted and read by an attacker. Suggest the most appropriate clientserver architecture for this system and, giving the reasons for your answer, propose how functionality should be distributed between the client and the server systems.

Short answer

Use a three-tier architecture with SSL/TLS, MFA, UI on the client, and business logic/authorization on the server.

Step-by-step solution

Choose Client-Server Architecture

The most appropriate client-server architecture for a system requiring strong authentication and secure communications is the three-tier architecture. This architecture separates the user interface, business logic, and data storage, enhancing security and scalability.

Ensure Secure Communication

To prevent interception and ensure secure communications, implement SSL/TLS protocols for encrypting data in transit. SSL/TLS provides a secure channel between the client and server, ensuring that all data transferred is encrypted and remains confidential.

Implement Strong Authentication

Use multi-factor authentication (MFA) to enhance security. This involves verifying at least two different factors of authentication, such as a password and a unique code sent to a user's mobile device.

Distribute Client-Server Functionality

Place the user interface and any non-sensitive operations on the client side, which improves responsiveness and decreases server load. Sophisticated business logic and data processing should reside on the server side to maintain control over sensitive operations and data integrity.

Authorization Management

Handle authorization on the server side, using role-based access control (RBAC) to ensure users have the necessary permissions for actions. This centralizes security management and limits user access to only what is necessary.

Key concepts

Client-Server Architecture

In the digital world, client-server architecture is a pivotal design concept used to separate functions in computer systems. It splits the workload between providers (servers) and requesters (clients). This enables systems to run efficiently and securely.
For a system requiring strong security like the one in our exercise, using a client-server model is crucial. This setup has the client applications focused on user interactions and some computing tasks, while the server handles complex processes and data storage.
By compartmentalizing tasks, systems not only improve performance and reliability but also enhance protection against unauthorized access. Distributing tasks in this way ensures that security measures are centralized and easier to control, enabling better protection of sensitive data.

Three-Tier Architecture

The three-tier architecture is a sophisticated form of client-server architecture. It divides the application into three layers: the user interface, the business logic, and the data storage layer.

• **User Interface Layer**: This is where interaction with users occurs. It runs on the client side, ensuring responsiveness and quick feedback.
• **Business Logic Layer**: Residing on the server, this layer manages the core functionalities and processes secure transactions or requests made by the user.
• **Data Storage Layer**: Also on the server, this keeps and manages data, ensuring safety and quick retrieval of information when needed.

By structuring an application in this way, it separates concerns, which makes the system more scalable, maintainable, and importantly, far more secure. This clear separation allows each layer to evolve independently without disrupting the others.

Authorization Management

In any secure system, effectively managing who can access what is vital. Authorization Management involves determining user access rights and permissions within a system.
A popular method is Role-Based Access Control (RBAC), where users are granted permissions based on assigned roles. For instance, an administrator might have access to modify system settings, while a regular user may only access their personal data.
This centralization of controls not only simplifies security management but ensures that users access only what is necessary. Implementing strong authorization management on the server particularly helps by keeping sensitive operations out of reach from unauthorized users, which is crucial for maintaining system integrity and confidentiality.

SSL/TLS Protocols

SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are protocols for securing data transmitted over networks. They provide privacy and data integrity by encrypting the information being shared between clients and servers.
Implementing SSL/TLS in the system prevents attackers from intercepting data during transmission, which is essential for maintaining confidentiality and trust.
To use SSL/TLS, systems must have digital certificates that verify the identities of communicating parties. Once a connection is established, data in transit is encrypted, making it nearly impossible for attackers to decipher it, thus guaranteeing secure communications within the system. This is a foundational security measure for systems that handle sensitive or personal information.