added tutorial

_config.yml

@@ -13,6 +13,7 @@ navbar-links:
     - Javascript - Vanilla: getting_started/javascript_spa
     - Python - FastAPI: https://github.com/passwordless-id/fast-api-demo
     - Java - Spring Boot: https://github.com/passwordless-id/spring-boot-demo
+    - .Net / C#: getting_started/dot_net
     - Want more?: getting_started/want_more
   Docs:
     - The "big picture": docs/1_big_picture

getting_started/dot_net.md

@@ -0,0 +1,45 @@
+Getting started with .Net
+=========================
+
+> Contributed by @moberauer, source: https://github.com/moberauer/passwordless.id-ASP.NET-Core-Demo
+
+# Passwordless.ID - ASP.NET Core Demo
+
+> This [example repository](https://github.com/moberauer/passwordless.id-ASP.NET-Core-Demo) shows an integration between [ASP.NET Core](https://dotnet.microsoft.com/en-us/apps/aspnet) and [Passwordless.ID](https://passwordless.id).
+>
+> The project uses the .NET web sdk and just one NuGet package needs to be installed: `Microsoft.AspNetCore.Authentication.OpenIdConnect`
+
+Using the OpenIdConnect SDK, set the default authentication scheme to OpenId, configure it to use the authoriozation code flow, the clientId and the metadata address provided by [Passwordless.ID](https://passwordless.id). Then we also add an external cookie scheme to store the user information once sign in via [Passwordless.ID](https://passwordless.id) was successful.
+
+
+```csharp
+var builder = WebApplication.CreateBuilder(args);
+builder.Services
+    .AddAuthentication(defaultScheme: OpenIdConnectDefaults.AuthenticationScheme)
+    .AddOpenIdConnect(openIdConnectOptions => 
+    {
+        openIdConnectOptions.SignInScheme = IdentityConstants.ExternalScheme;
+        openIdConnectOptions.ResponseType = OpenIdConnectResponseType.Code;
+        openIdConnectOptions.ClientId = "https://localhost";
+        openIdConnectOptions.MetadataAddress = "https://api.passwordless.id/.well-known/openid-configuration";
+    })
+    .AddExternalCookie();
+builder.Services.AddAuthorization();
+var app = builder.Build();
+```
+Now we configure the request pipeline to use the authentication and authorization middleware provided by ASP.NET Core and we map two endpoints: one which does not require authentication and one which does.
+
+```csharp
+var app = builder.Build();
+app.UseAuthentication();
+app.UseAuthorization();
+app.MapGet("/", () => "Go to /private to authenticate");
+app.MapGet("/private", context => {
+    string username = context.User.FindFirst("preferred_username")?.Value ?? string.Empty;
+    return context.Response.WriteAsync($"Hello, {username}!");
+}).RequireAuthorization();
+
+app.Run();
+```
+
+When we hit the authorized endpoint the authentication and authorization middleware take care of the redirects and callbacks to [Passwordless.ID](https://passwordless.id), code retrieval, id_token retrieval and storing the userinfo in the external cookie scheme cookie named *Identity.External*. The user information including all the claims provided by [Passwordless.ID](https://passwordless.id) is then available to our endpoint code via *context.User*.