Microsoft Identity Web : Azure AD Client Credential flow with Certificate Based Authentication

Question

I am connecting to Graph API with Microsoft Identity Web (MSAL) library. [https://github.com/AzureAD/microsoft-identity-web][1]

For this I am using client credentials flow with certificate based authentication.

My configurations are below

Service Registration

  services.AddMicrosoftIdentityWebApiAuthentication(Configuration)
           .EnableTokenAcquisitionToCallDownstreamApi()
           .AddMicrosoftGraph(Configuration.GetSection("DownstreamApi"))
           .AddInMemoryTokenCaches();

appSettings.json

"AzureAd": {
    "Instance": "https://login.microsoftonline.com/",
    "Domain": "mydomain.onmicrosoft.com",
    "TenantId": "xxxxxxx",
    "ClientId": "yyyyyyyy",   
    "ClientCertificates": [
     {
       "SourceType": "Path",
       "CertificateDiskPath": "c:\\cert\\my-cert.pfx",
       "CertificatePassword": "password"
     }
 ] }

For this I am getting the below error

IDW10104: Both client secret and client certificate cannot be null or whitespace, and only ONE must be included in the configuration of the web app when calling a web API. For instance, in the appsettings.json file.

However I am able to accrue token and connect with Graph API using Microsoft.Identity.Client (Using client credentials-flow with certificate based auth)

    private GraphServiceClient GetGraphServiceClient()
    {
        var token = GetToken();
        GraphServiceClient graphServiceClient =
            new GraphServiceClient(new DelegateAuthenticationProvider(async (requestMessage) =>
            {
                // Add the access token in the Authorization header of the API request.
                requestMessage.Headers.Authorization =
                        new AuthenticationHeaderValue("Bearer", token);
            })
            );
        return graphServiceClient;
    }

    private string GetToken()
    {
        var x509Certificate2 = 
            new X509Certificate2(System.IO.File.ReadAllBytes("MyCert.pfx"), "password");

        IConfidentialClientApplication app = 
            Microsoft.Identity.Client.ConfidentialClientApplicationBuilder.Create("my-client-id")
                .WithTenantId("my-tenent-id")
                .WithCertificate(x509Certificate2)
                .Build();

        // With client credentials flows the scopes is ALWAYS of the shape "resource/.default", as the
        // application permissions need to be set statically (in the portal or by PowerShell), and then granted by
        // a tenant administrator
        string[] scopes = new string[] { "https://graph.microsoft.com/.default" };
         
        AuthenticationResult result =
                    app.AcquireTokenForClient(scopes)
                        .ExecuteAsync().Result;
        return result.AccessToken;
    }

Am I missing any configuration here?

score 1 · Answer 1 · answered Dec 24 '21 at 10:41

On workaround

Try with the adding the certificate in the Azure App registration

1) Go to the Azure portal. In the left-hand navigation pane, select the Azure Active Directory service, and then select App registrations.

2) In the resultant screen, select the Select the your application.

3) In the Certificates & secrets tab, go to Certificates section:

4) Select Upload certificate and, in select the browse button on the right to select the your existing certificate.

5) Select Add.

For more details refer this document: https://github.com/Azure-Samples/active-directory-aspnetcore-webapp-openidconnect-v2/blob/master/4-WebApp-your-API/4-1-MyOrg/README-use-certificate.md

I hope not really in my case. Because ClientCertificates value from appSettings.json is not binding when I am using => services.AddMicrosoftIdentityWebApiAuthentication(Configuration) — Anand, Dec 24 '21 at 14:33

Microsoft Identity Web : Azure AD Client Credential flow with Certificate Based Authentication

1 Answers1