Auth Recipe — C# (.NET) — REFERENCE ONLY

Microsoft Identity Web (ASP.NET Core)

NuGet Packages

<PackageReference Include="Microsoft.Identity.Web" Version="3.*" />

Program.cs (additions)

Add these lines — do NOT replace the existing file:

using Microsoft.Identity.Web;

// Add after builder creation
builder.Services.AddMicrosoftIdentityWebApiAuthentication(builder.Configuration);
builder.Services.AddAuthorization();

// Add after app build
app.UseAuthentication();
app.UseAuthorization();

// Protected endpoint
app.MapGet("/api/me", [Authorize] (HttpContext ctx) =>
{
    var name = ctx.User.FindFirst("name")?.Value;
    return Results.Ok(new { name });
});

appsettings.json

{
  "AzureAd": {
    "Instance": "https://login.microsoftonline.com/",
    "TenantId": "<tenant-id>",
    "ClientId": "<client-id>",
    "Audience": "api://<client-id>"
  }
}

⚠️ The Audience must match the Application ID URI of the app registration (typically api://<client-id>). Set AZURE_CLIENT_ID and AZURE_TENANT_ID as app settings in Azure rather than hardcoding them.

Files to Modify