ASP.NET Core authentication middleware configuration including OpenID Connect, JWT Bearer, cookie authentication, authentication schemes, challenge/forbid flows, and external identity provider integration.

ASP.NET Core authorization patterns including policy-based authorization, IAuthorizationHandler implementations, scope-based authorization for APIs, authorization middleware configuration, and minimal API authorization.

Claims transformation and profile service patterns for Duende IdentityServer — IProfileService, IClaimsTransformation, claim type mapping, token claim filtering, extension grant validators, and dynamic claims loading.

Duende BFF (Backend for Frontend) security framework for securing SPAs. Covers session management, API endpoint proxying, token management, anti-forgery protection, and integration with React/Angular/Blazor frontends.

Security hardening for Duende IdentityServer deployments including signing key rotation, HTTPS enforcement, CORS configuration, CSP headers, rate limiting, token lifetime tuning, and security audit patterns.

Testing patterns for IdentityServer-based systems including integration testing with WebApplicationFactory, mock token issuance, test authority configuration, protocol response validation, and end-to-end authentication flow testing.

Protecting APIs with Duende IdentityServer: JWT bearer authentication, reference token introspection, scope-based authorization, DPoP/mTLS proof-of-possession validation, local API authentication, and multi-audience scenarios.

Orchestrate Duende IdentityServer in .NET Aspire AppHost — dependency graphs, authority URL wiring, health checks, and multi-instance.

Configure Duende IdentityServer including client definitions, API resources, identity resources, scopes, signing credentials, and server-side sessions. Covers client types (M2M, interactive, SPA), grant types, API Scopes vs API Resources vs Identity Resources, secret management, and client authentic

Configuring Dynamic Client Registration (DCR) in Duende IdentityServer: endpoint setup, authorization policies, custom validation with DynamicClientRegistrationValidator, software statement validation, IClientConfigurationStore, and separate DCR hosting.

Guide for deploying Duende IdentityServer to production, covering reverse proxy configuration, data protection, health checks, distributed caching, multi-instance deployment, OpenTelemetry integration, logging, and common deployment pitfalls.

Setting up and hosting Duende IdentityServer in ASP.NET Core applications, including DI registration, middleware pipeline, hosting patterns, essential options, license configuration, and ASP.NET Identity integration.

Managing cryptographic signing keys in Duende IdentityServer, including automatic key management, KeyManagementOptions, data protection at rest, static key configuration, migration from static to automatic, and multi-instance deployment considerations.

Configuring Duende IdentityServer as a SAML 2.0 Identity Provider (IdP): service provider registration, SSO and SLO flows, claim mappings, extensibility interfaces, and production deployment patterns.

Guide for configuring server-side sessions, session management and querying, inactivity timeout, dynamic identity providers, and CIBA (Client Initiated Backchannel Authentication) in Duende IdentityServer.

Implement and customize Duende IdentityServer stores including configuration store, operational store, and Entity Framework Core integration. Covers migrations, custom store implementations, caching strategies, server-side sessions, signing key storage, token cleanup, and multi-tenant patterns.

Guide for implementing token types, refresh token management, token exchange (RFC 8693), extension grants, IProfileService claims customization, and token lifetime best practices in Duende IdentityServer.

Advanced token security features in Duende IdentityServer including DPoP, mTLS certificate binding, Pushed Authorization Requests (PAR), JWT Secured Authorization Requests (JAR), and FAPI 2.0 compliance configuration.

Guide for building login, logout, consent, error, and federation gateway UI pages in Duende IdentityServer, including IIdentityServerInteractionService usage, external provider integration, and Home Realm Discovery strategies.

Migrating Duende IdentityServer from v7.4 to v8.0: breaking changes, API replacements (ICache→HybridCache, IClock→TimeProvider), CancellationToken additions, EF migrations, and step-by-step upgrade guide.

Setting up Duende User Management with IdentityServer: passwordless authentication (OTP, TOTP, passkeys), storage configuration, user lifecycle, and migration from ASP.NET Identity.

Migrating from IdentityServer4 to Duende IdentityServer v8. Covers NuGet package replacement, namespace changes, API surface changes, EF Core database schema migrations, .NET target framework upgrade, license configuration, signing key migration, data protection, and UI template updates.

OAuth 2.0 and OpenID Connect protocol fundamentals including authorization code flow with PKCE, client credentials, refresh tokens, discovery documents, JWKS, and token introspection. Protocol-level troubleshooting and compliance.

Token management patterns using Duende.AccessTokenManagement. Covers client credential token caching, user token refresh, token storage, HttpClientFactory integration, DPoP support, and common configuration pitfalls. Also includes Blazor Server token management.

Expert in Duende IdentityServer configuration, deployment, and troubleshooting. Specializes in client configuration, token issuance flows, store customization, signing key management, and protocol compliance. Use for diagnosing authentication failures, token validation issues, and IdentityServer arc

Expert in OAuth 2.0 and OpenID Connect protocol specifications, security best practices, and compliance. Specializes in flow selection, token security, protocol-level debugging, and standards compliance. Use for protocol design decisions, security reviews, and debugging token/auth flows at the HTTP