ASP.NET - ASP.NET Authorization Handlers

ASP.NET authorization handlers are components that contain the logic used to decide whether a user is allowed to access a resource. They evaluate authorization requirements against the current user and request context, making access decisions flexible and rule-based instead of hard-coded.

What Authorization Handlers Do
An authorization handler checks whether a specific requirement is satisfied. It examines the user’s claims, roles or other contextual data and determines if access should be granted. Each handler focuses only on authorization logic, not authentication or business processing.

Relationship Between Policies, Requirements and Handlers
Authorization policies define what is required, requirements describe the condition to be met and handlers contain the logic to evaluate those conditions. This separation keeps authorization structured and readable, especially in applications with complex access rules.

When Authorization Handlers Run
Authorization handlers execute after authentication and claim or role transformation. They run before the endpoint logic is executed. This ensures all identity data is prepared and validated before access decisions are made.

Why Authorization Handlers Are Needed
Simple role or claim checks are often not enough for real applications. Authorization handlers allow checks such as ownership validation, time-based access, feature entitlement and context-aware permissions. This makes access control accurate and business-driven.

Multiple Handlers and Evaluation Flow
An application can have multiple authorization handlers. Each handler evaluates its assigned requirement independently. Access is granted only when all required conditions are satisfied. This modular approach makes authorization rules easier to manage and extend.

Security and Design Advantages
Authorization handlers centralize access control logic and keep it separate from controllers or endpoints. This improves maintainability, reduces duplication and ensures consistent security behavior across the application. Proper use of handlers leads to cleaner code and stronger authorization design.