Merits and Demerits of Centralized and Decentralized Authorization

Centralized authorization involves a single, dedicated entity that makes all access control decisions for a system or network. This contrasts with decentralized authorization, where authorization decisions are distributed among multiple entities or resources throughout the system.

Centralized Authorization

Merits:

• Simplified Management and Policy Enforcement: Policies are defined and managed from a single point, making it easier to ensure consistency across the entire system. For example, in a corporate network, a single Identity and Access Management (IAM) server might control access to all file shares and applications.
• Consistent Application of Policies: A single authority ensures that all access rules are uniformly applied, reducing the chance of policy conflicts or loopholes.
• Streamlined Auditing: All authorization logs are collected at one location, simplifying the process of tracking and reviewing access decisions for compliance and security monitoring.
• Reduced Administrative Complexity: Administrators have one primary system to configure and maintain for authorization.

Demerits:

• Single Point of Failure: If the central authorization server becomes unavailable, all access decisions cease, effectively locking users out of resources.
• Scalability Bottleneck: As the number of users and resources grows, the central server can become a performance bottleneck due to the increasing load of authorization requests.
• Increased Network Latency: Every authorization request must travel to the central server and back, which can introduce delays, especially in geographically dispersed systems.
• Limited Flexibility: A single set of policies might not adequately address the diverse security needs of different departments or applications within a large organization.

Decentralized Authorization

Merits:

• Enhanced Scalability: Authorization decisions are distributed, allowing the system to scale more effectively as the load is spread across multiple points.
• Improved Resilience and Availability: The absence of a single point of failure means that if one authorization component fails, others can continue to operate, maintaining system availability. This is akin to the distributed authorization model discussed by Kahan (1995) for the WWW.
• Greater Flexibility: Authorization policies can be tailored to the specific needs of individual resources or services, allowing for more granular and adaptive security controls.
• Reduced Network Latency: Decisions can be made closer to the resource, or even by the resource itself, reducing network overhead and speeding up access.

Demerits:

• Increased Management Complexity: Managing and synchronizing policies across multiple distributed authorization points can be complex and error-prone.
• Potential for Policy Inconsistencies: Ensuring that all distributed authorization components adhere to an overarching security policy can be challenging, potentially leading to security gaps.
• Difficult Auditing: Collecting and consolidating authorization logs from numerous distributed points for comprehensive auditing is often more complex than with a centralized approach.
• Higher Overhead per Component: Each component or service needs to incorporate its own authorization logic, increasing development and maintenance effort.

Both approaches have their places, depending on the system's size, security requirements, and architectural considerations, as outlined in general computer security principles such as those found in Kizza's Guide to Computer Network Security.