Azure B2C authentication screen does not show up

Question

I have an Asp.Net 4.7 WebForms legacy application written in vb.net. I need to add Azure B2C authentication. So I registred an app with Azure, and added OWIN middleware NuGet packages, and made all necessary configuration changes. I expect to see the log in screen when the application runs, and yet it does not happen. The application just runs without any authentication. What am I missing?

Here is the code:

Startup.vb:

Imports System.Threading.Tasks
Imports Microsoft.IdentityModel.Protocols.OpenIdConnect
Imports Microsoft.IdentityModel.Tokens
Imports Microsoft.Owin
Imports Microsoft.Owin.Security
Imports Microsoft.Owin.Security.Cookies
Imports Microsoft.Owin.Security.Notifications
Imports Microsoft.Owin.Security.OpenIdConnect
Imports Owin


Namespace InfoWebCore
Public Class Startup
    Private Shared clientId As String = ConfigurationManager.AppSettings("ida:ClientId")
    Private Shared aadInstance As String = ConfigurationManager.AppSettings("ida:AadInstance")
    Private Shared tenant As String = ConfigurationManager.AppSettings("ida:Tenant")
    Private Shared redirectUri As String = ConfigurationManager.AppSettings("ida:RedirectUri")
    Public Shared SignInPolicyId As String = ConfigurationManager.AppSettings("ida:SignInPolicyId")

    Public Sub Configuration(ByVal app As IAppBuilder)
        app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType)
        app.UseCookieAuthentication(New CookieAuthenticationOptions())
        app.UseOpenIdConnectAuthentication(CreateOptionsFromPolicy(SignInPolicyId))
    End Sub

    Private Function AuthenticationFailed(ByVal notification As AuthenticationFailedNotification(Of OpenIdConnectMessage, OpenIdConnectAuthenticationOptions)) As Task
        notification.HandleResponse()

        If notification.Exception.Message = "access_denied" Then
            notification.Response.Redirect("/")
        Else
            notification.Response.Redirect("/Home/Error?message=" & notification.Exception.Message)
        End If

        Return Task.FromResult(0)
    End Function

    Private Function CreateOptionsFromPolicy(ByVal policy As String) As OpenIdConnectAuthenticationOptions
        Dim options = New OpenIdConnectAuthenticationOptions With {
            .MetadataAddress = String.Format(aadInstance, tenant, policy),
            .AuthenticationType = policy,
            .ClientId = clientId,
            .RedirectUri = redirectUri,
            .PostLogoutRedirectUri = redirectUri,
            .Notifications = New OpenIdConnectAuthenticationNotifications With {
                .AuthenticationFailed = AddressOf AuthenticationFailed
            },
            .Scope = "openid",
            .ResponseType = "id_token",
            .TokenValidationParameters = New TokenValidationParameters With {
                .NameClaimType = "name"
            }
        }
        Return options
    End Function
End Class
End Namespace

Web.config:

...

Execution does come to the Configuration() method...

AlfredoRevilla-MSFT · Accepted Answer

All looks good, please ensure your web.config is similar to this:

And your StartupAuth.vb is similar to:

Imports System.Security.Claims
Imports System.Threading.Tasks
Imports Microsoft.IdentityModel.Protocols.OpenIdConnect
Imports Microsoft.IdentityModel.Tokens
Imports Microsoft.Owin.Extensions
Imports Microsoft.Owin.Security
Imports Microsoft.Owin.Security.Cookies
Imports Microsoft.Owin.Security.OpenIdConnect
Imports Owin

Partial Public Class Startup
    Private Shared clientId As String = ConfigurationManager.AppSettings("ida:ClientId")
    Private Shared aadInstance As String = ConfigurationManager.AppSettings("ida:AadInstance")
    Private Shared tenant As String = ConfigurationManager.AppSettings("ida:Tenant")
    Private Shared redirectUri As String = ConfigurationManager.AppSettings("ida:RedirectUri")
    Public Shared SignInPolicyId As String = ConfigurationManager.AppSettings("ida:SignInPolicyId")

    Public Sub ConfigureAuth(app As IAppBuilder)
        app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType)

        app.UseCookieAuthentication(New CookieAuthenticationOptions())

        app.UseOpenIdConnectAuthentication(CreateOptionsFromPolicy(SignInPolicyId))

        app.UseStageMarker(PipelineStage.Authenticate)
    End Sub

    Private Function CreateOptionsFromPolicy(ByVal policy As String) As OpenIdConnectAuthenticationOptions
        Dim options = New OpenIdConnectAuthenticationOptions With {
            .MetadataAddress = "https://alfredorevillaatmsftb.b2clogin.com/tfp/alfredorevillaatmsftb.onmicrosoft.com/B2C_1_SI/v2.0/.well-known/openid-configuration",
            .RedirectUri = redirectUri,
            .PostLogoutRedirectUri = redirectUri,
            .ClientId = clientId,
            .Scope = "openid",
            .ResponseType = "id_token"
        }
        Return options
    End Function

    Private Function AuthenticationFailed(ByVal notification As Notifications.AuthenticationFailedNotification(Of OpenIdConnectMessage, OpenIdConnectAuthenticationOptions)) As Task
        notification.HandleResponse()

        If notification.Exception.Message = "access_denied" Then
            notification.Response.Redirect("/")
        Else
            notification.Response.Redirect("/Home/Error?message=" & notification.Exception.Message)
        End If

        Return Task.FromResult(0)
    End Function

    Private Shared Function EnsureTrailingSlash(ByRef value As String) As String
        If (IsNothing(value)) Then
            value = String.Empty
        End If

        If (Not value.EndsWith("/", StringComparison.Ordinal)) Then
            Return value & "/"
        End If

        Return value
    End Function
End Class

Also, https://login.microsoftonline.com is going to get deprecated soon. Please use b2login.com as detailed in Set redirect URLs to b2clogin.com for Azure Active Directory B2C.

Azure B2C authentication screen does not show up

Answers (1)

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