Authentication & Authorization in .NET

Authentication establishes identity. Authorization enforces access rights. For .NET developers, these are not optional features—they are foundational control requirements that ISO/IEC 27001 explicitly demands (A.9: Access Control).

Authentication patterns vary by application type: cookie-based sessions for traditional web applications, JWT tokens for stateless APIs, and federated identity through Azure AD B2C for external-facing systems. Each pattern has security implications and operational consequences that affect overall system trustworthiness.

Authentication Patterns in .NET

ASP.NET Core provides multiple authentication schemes. The choice determines security properties: how sessions are invalidated, whether tokens can be revoked, how credential compromise is mitigated. Claims-based authorization builds on authenticated identity to enforce granular access control—not just “who you are” but “what you’re allowed to do.”

Proper authentication implementation requires: strong session timeout policies, multi-factor authentication for privileged operations, credential rotation mechanisms, and audit logging of authentication failures. These aren’t optional “security hardening” steps—they are baseline engineering requirements.

Your [Authorize] Attribute Is Compliance Theater

Your [Authorize] attributes give you a false sense of security. ISO 27001 auditors see right through it.

I’ve reviewed dozens of ASP.NET Core apps that authenticate flawlessly — then scatter role strings across business logic, skip audit logs, and wonder why they fail compliance. Here’s the pattern that kills audits, and how to actually fix it.