Highly Secured regular Web Application

In this tutorial, we will provide a comprehensive explanation of the process involved in creating a highly secure regular Web Application that adheres to all the security recommendations outlined in the FAPI (Financial-grade API) specifications. The FAPI specifications can be found at https://openid.net/specs/fapi-2_0-baseline.html#name-requirements-for-clients :

• The client shall support MTLS or DPoP as mechanism for sender-constrained access tokens.
• The client shall include request or request_uri parameter as defined in Section 6 of OIDC in the authentication request.
• If the Authorization Request is too large for example a Rich Authorization Request, then it is recommended to use Pushed Authorization Request (PAR).
• JWT-Secured OAUTH2.0 authorisation response (JARM) is used to sign and / or encrypt the authorisation response, it protects against replay, credential leaks and mix-up attacks.
• The PS256 or ES256 algorithms must be used.

Based on the algorithm you have chosen to implement for Proof of Possession, please refer to the appropriate chapter to configure your highly secure web application

info

The source code of this project can be found here.

MTLS

The website will be configured with the following settings:

Configuration	Value
Client Authentication Method	tls_client_auth
Authorization Signed Response Algorithm	ES256
Identity Token Signed Response Algorithm	ES256
Request Object Signed Response Algorithm	ES256
Pushed Authorization Request	Yes
Response Mode	jwt

To incorporate all the FAPI recommendations into your regular web application, it is necessary to follow the following steps:

1. Configure client certificate

Utilize the administration UI to create a client certificate.

1. Open the IdentityServer website at https://localhost:5002.
2. In the Certificate Authorities screen, choose a Certificate Authority from the available options. Remember that the selected Certificate Authority should be trusted by your machine. You can download the certificate and import it into the appropriate Certificate Store.
3. Click on the Client Certificates tab and then proceed to click on the Add Client Certificate button.
4. Set the value of the Subject Name to CN=websiteFAPI and click on the Add button.
5. Click on the Download button located next to the certificate.

2. Configure an application

1. Open the IdentityServer website at https://localhost:5002.
2. On the Clients screen, click on the Add client button.
3. Choose FAPI2.0 template.
4. Select Highly secure Web Application and click on next.
5. Fill-in the form like this and click on the Save button to confirm the creation.

Property	Value
Identifier	websiteFAPIMTLS
Secret	password
Name	websiteFAPIMTLS
Redirection URLs	http://localhost:5003/signin-oidc
Proof of Possession	Mutual-TLS Client Authentication
Subject Name	CN=websiteFAPI

6. The generated JSON Web Key will be displayed. Copy the corresponding value and save it in a text file. It will be used by the web application to construct a signed request parameter.

Now your client is ready to be used, you can develop the regular website.

3. Create ASP.NET CORE Application

Finally, create and configure an ASP.NET CORE Application.

1. Open a command prompt and execute the following commands to create the directory structure for the solution.

mkdir HighlySecuredServersideWebsite
cd HighlySecuredServersideWebsite
mkdir src
dotnet new sln -n HighlySecuredServersideWebsite

info

This NuGet Package includes support for all the features provided by the official Microsoft.AspNetCore.Authentication.OpenIdConnect NuGet Package. Additionally, it introduces new features such as the tls_client_auth Client Authentication Method and supports new authorization response types including jwt, query.jwt, fragment.jwt, form_post.jwt, fragment.jwt, Pushed Authorization Request (PAR) and DPoP.

cd src
dotnet new mvc -n Website
cd Website
dotnet add package SimpleIdServer.OpenIdConnect

2. Add the Website project into your Visual Studio solution.

cd ..\..
dotnet sln add ./src/Website/Website.csproj

3. In the Program.cs file, make the following modifications to configure the OPENID authentication: Replace the content of the JWK.json file with the content from the file you copied earlier (step 2.5). Make sure to replace the certificate CN=websiteFAPI.pfx with the one you downloaded earlier (step 1.5).

Configuration	Value
Client Authentication Method	tls_client_auth
Authorization Signed Response Algorithm	ES256
Identity Token Signed Response Algorithm	ES256
Request Object Signed Response Algorithm	ES256
Pushed Authorization Request	Yes
Response Mode	jwt

    var certificate = new X509Certificate2(Path.Combine(Directory.GetCurrentDirectory(), "CN=websiteFAPI.pfx"));
    var serializedJwk = File.ReadAllText(Path.Combine(Directory.GetCurrentDirectory(), "JWK.json")); 
    var jsonWebKey = JsonExtensions.DeserializeFromJson<JsonWebKey>(serializedJwk);
    builder.Services.AddAuthentication(options =>
    {
        options.DefaultScheme = "Cookies";
        options.DefaultChallengeScheme = "sid";
    })
        .AddCookie("Cookies")
        .AddCustomOpenIdConnect("sid", options =>
        {
            options.SignInScheme = "Cookies";
            options.ResponseType = "code";
            options.ResponseMode = "jwt";
            options.Authority = "https://localhost:5001/master";
            options.RequireHttpsMetadata = false;
            options.ClientId = "websiteFAPIMTLS";
            options.GetClaimsFromUserInfoEndpoint = true;
            options.SaveTokens = true;
            options.UseMTLSProof(certificate, new SigningCredentials(jsonWebKey, jsonWebKey.Alg));
        });

4. Add a ClaimsController controller with one protected operation.

public class ClaimsController : Controller
{
    [Authorize]
    public IActionResult Index()
    {
        return View();
    }
}

5. Create a view Views\Claims\Index.cshtml with the following content. This view will display all the claims of the authenticated user.

<ul>
    @foreach (var claim in User.Claims)
    {
        <li>@claim.Type : @claim.Value</li>
    }
</ul>

6. In a command prompt, navigate to the directory src\Website and launch the application.

dotnet run --urls=http://localhost:5003

Finally, browse the following URL: http://localhost:5003/claims. The User-Agent will be automatically redirected to the OpenID server. Submit the following credentials and confirm the consent. You will be redirected to the screen where your claims will be displayed

Credential	Value
Login	administrator
Password	password

DPoP

The website will be configured with the following settings:

Configuration	Value
Client Authentication Method	private_key_jwt
Authorization Signed Response Algorithm	ES256
Identity Token Signed Response Algorithm	ES256
Request Object Signed Response Algorithm	ES256
Pushed Authorization Request	Yes
Response Mode	jwt

To incorporate all the FAPI recommendations into your regular web application, it is necessary to follow the following steps:

1. Configure an application

1. Open the IdentityServer website at https://localhost:5002.
2. On the Clients screen, click on the Add client button.
3. Choose FAPI2.0 template.
4. Select Highly secure Web Application and click on next.
5. Fill-in the form like this and click on the Save button to confirm the creation.

Property	Value
Identifier	websiteFAPIDPoP
Secret	password
Name	websiteFAPIDPoP
Redirection URLs	http://localhost:5003/signin-oidc
Proof of Possession	DPoP

6. The generated JSON Web Key will be displayed. Copy the corresponding value and save it in a text file. It will be used by the web application to construct a signed request parameter and a signed DPoP Proof.

Now your client is ready to be used, you can develop the regular website.

2. Create ASP.NET CORE Application

Finally, create and configure an ASP.NET CORE Application.

1. Open a command prompt and execute the following commands to create the directory structure for the solution.

mkdir HighlySecuredServersideWebsite
cd HighlySecuredServersideWebsite
mkdir src
dotnet new sln -n HighlySecuredServersideWebsite

info

This NuGet Package includes support for all the features provided by the official Microsoft.AspNetCore.Authentication.OpenIdConnect NuGet Package. Additionally, it introduces new features such as the tls_client_auth Client Authentication Method and supports new authorization response types including jwt, query.jwt, fragment.jwt, form_post.jwt, fragment.jwt, Pushed Authorization Request (PAR) and DPoP.

cd src
dotnet new mvc -n Website
cd Website
dotnet add package SimpleIdServer.OpenIdConnect

2. Add the Website project into your Visual Studio solution.

cd ..\..
dotnet sln add ./src/Website/Website.csproj

3. In the Program.cs file, make the following modifications to configure the OPENID authentication: Replace the content of the JWK.json file with the content from the file you copied earlier (step 2.5).

Configuration	Value
Client Authentication Method	private_key_jwt
Authorization Signed Response Algorithm	ES256
Identity Token Signed Response Algorithm	ES256
Request Object Signed Response Algorithm	ES256
Pushed Authorization Request	Yes
Response Mode	jwt

    var serializedJwk = File.ReadAllText(Path.Combine(Directory.GetCurrentDirectory(), "JWK.json"));
    var jwk = JsonExtensions.DeserializeFromJson<JsonWebKey>(serializedJwk);
    builder.Services.AddAuthentication(options =>
    {
        options.DefaultScheme = "Cookies";
        options.DefaultChallengeScheme = "sid";
    })
        .AddCookie("Cookies")
        .AddCustomOpenIdConnect("sid", options =>
        {
            options.SignInScheme = "Cookies";
            options.ResponseType = "code";
            options.ResponseMode = "jwt";
            options.Authority = "https://localhost:5001/master";
            options.RequireHttpsMetadata = false;
            options.ClientId = "websiteFAPIDPoP";
            options.GetClaimsFromUserInfoEndpoint = true;
            options.SaveTokens = true;
            options.UseDPoPProof(new SigningCredentials(jwk, jwk.Alg));
        });

4. Add a ClaimsController controller with one protected operation.

public class ClaimsController : Controller
{
    [Authorize]
    public IActionResult Index()
    {
        return View();
    }
}

5. Create a view Views\Claims\Index.cshtml with the following content. This view will display all the claims of the authenticated user.

<ul>
    @foreach (var claim in User.Claims)
    {
        <li>@claim.Type : @claim.Value</li>
    }
</ul>

6. In a command prompt, navigate to the directory src\Website and launch the application.

dotnet run --urls=http://localhost:5003

Finally, browse the following URL: http://localhost:5003/claims. The User-Agent will be automatically redirected to the OpenID server. Submit the following credentials and confirm the consent. You will be redirected to the screen where your claims will be displayed

Credential	Value
Login	administrator
Password	password