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 Logout Button Is Lying: ASP.NET Session Security Done Right

That StackOverflow answer suggesting Session.Timeout = Int32.MaxValue for “better UX”? It’s how security becomes checkbox theater. Sessions that never expire, logout buttons that don’t invalidate tokens, cookies transmitted over HTTP—auditors catch these patterns immediately. Here’s how to configure ASP.NET Core authentication that actually works.

Cookie Banners Won't Save You From ISO 27701

That boolean column you call “consent”? Regulators will laugh at it.

ISO 27701 demands granular, auditable, expiring consent, not cookie theater. Here’s the complete .NET implementation with Entity Framework Core, middleware validation, and Azure Functions that survives an audit.

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.