Azure AD B2C implementation #7702

0

philhu created 4 years ago

Hi, here is how I proceeded to implement Azure AD B2C OpenID :

In Azure AD, find your tenant name and tenant ID (= Directory ID)
In Azure AD B2C, find your signup/signin policy, and your application ID. Verify the application claims and make sure you check Email Address, Given Name, Surname
Enable OpenID in appsettings.json:

"OpenId": {
      "IsEnabled": "true",
      "ClientId": "<applicationID>",
      "Authority": "https://<TenantName>.b2clogin.com/tfp/<TenantID>/b2c_1_signin/v2.0/",
      "LoginUrl": "https://<TenantName>.b2clogin.com/tfp/<TenantName>.onmicrosoft.com/<signupin_policy>/oauth2/v2.0/authorize",
      "ValidateIssuer": "false"
    },

Azure AD does not provide unique_name and email in the claims (it provide emails). To address this issue, I followed the technique explained in Question 5773 and implemented the class OpenIdConnectAuthProviderApi OpenIdConnectAuthProviderApi in YourProject.Web.Core\Authentication\External\OpenIdConnectAuthProviderApi .cs.
You have to change the lines that decode the claims (it was originally written for okta):

var givenname = validatedToken.Claims.First(c => c.Type == "given_name").Value;
var surname = validatedToken.Claims.First(c => c.Type == "family_name").Value; 
var emails = validatedToken.Claims.First(c => c.Type == "emails").Value;
var email = string.Empty;
if (!string.IsNullOrEmpty(emails)) email = emails.Split(' ').First();

return new ExternalAuthUserInfo
{
     Provider = Name,
     ProviderKey = validatedToken.Subject,
     Name = givenname,
     Surname = surname,
     EmailAddress = email
  };

Now edit GetExternalUserInfo in YourProject.Web.Core\Controllers\TokenAuthController.cs to use the proper version of GetUserInfo:

private async Task<ExternalAuthUserInfo> GetExternalUserInfo(ExternalAuthenticateModel model)
 {
     ExternalAuthUserInfo userInfo = null;
     if (model.AuthProvider == OpenIdConnectAuthProviderApi.Name)
         userInfo = await _openIdConnectAuthProviderApi.GetUserInfo(model.AuthProvider, model.ProviderAccessCode);
     else
         userInfo = await _externalAuthManager.GetUserInfo(model.AuthProvider, model.ProviderAccessCode);

      if (userInfo.ProviderKey != model.ProviderKey)
      {
           throw new UserFriendlyException(L("CouldNotValidateExternalUser"));
       }

     return userInfo;
}

(do not forget to instantiate _openIdConnectAuthProviderApi; see how _externalAuthManager is instantiated)

I found useful to add

            if (bool.Parse(configuration["Authentication:OpenId:IsEnabled"]))
            {
                IdentityModelEventSource.ShowPII = true;
            }

in AcmePhoneBookDemo.Web.Startup::AuthConfigurer::Configure. It enables revealing the PII exception messages.

0

ismcagdas created 4 years ago

Support Team

Hi @philhu

Instead of creating a custom implementation of OpenIdConnectAuthProviderApi, you can use ClaimsMappings section of OpenId configuration in appsettings.json. It allows you to map email claim to unique_name.

0

ismcagdas created 4 years ago

Support Team

This issue is closed because of no recent activity. Please open a new issue if you are still having this problem.

Azure AD B2C implementation #7702

3 Answer(s)