Webauthn Authentication

WebAuthn (Web Authentication) is a modern authentication standard that enables secure, passwordless login experiences by leveraging public key cryptography. By using hardware security keys or built-in biometric sensors, WebAuthn significantly reduces the risks associated with traditional password-based authentication, providing an additional layer of security against phishing and other attacks.

To integrate WebAuthn authentication into your identity server, you first need to install the NuGet package SimpleIdServer.IdServer.Fido. This package provides the necessary components to implement WebAuthn using the FIDO2 protocol.

Step 1 : Install the NuGet Package

Open your command line and execute the following command:

cmd.exe

dotnet add package SimpleIdServer.IdServer.Fido

This command adds the package to your project, ensuring that you have all the dependencies needed for WebAuthn.

Step 2 : Configure the Identity Server

After installing the package, you need to configure your identity server by modifying the Program.cs file. The configuration is done using a fluent API call to AddWebauthnAuthentication, which accepts two parameters:

• The first parameter allows you to customize the default configuration of the Fido2NetLib library.
• The second parameter indicates whether WebAuthn should be the default authentication method for the identity server.

Below is an example of a fully configured identity server in C#:

Program.cs

webApplicationBuilder.Configuration.AddJsonFile("appsettings.json")
    .AddJsonFile($"appsettings.{webApplicationBuilder.Environment.EnvironmentName}.json", optional: true)
    .AddEnvironmentVariables();
webApplicationBuilder.AddSidIdentityServer()
    .AddDeveloperSigningCredential()
    .AddInMemoryRealms(Config.Realms)
    .AddInMemoryUsers(Config.Users)
    .AddInMemoryLanguages(Config.Languages)
    .AddWebauthnAuthentication(null, true);

var app = webApplicationBuilder.Build();
app.Services.SeedData();
app.UseSid();
app.Run();

Step 3: Configure WebAuthn Options

The SimpleIdServer.IdServer.Fido library is further configurable via the appsettings.json file by adding a WebauthnOptions section. This section allows you to define properties such as the expiration time for the authentication process. For example:

Property	Value
U2FExpirationTimeInSeconds	The duration (in seconds) for the authentication process

Here is an example configuration:

appsettings.json

"WebauthnOptions": {
    "U2FExpirationTimeInSeconds": "20"
}

The authentication window provided by the system is minimalistic, featuring a single field where the user can enter their login. This streamlined design helps reduce complexity and improves the user experience during the authentication process