Imports System
Imports System.Web
Imports System.Web.UI
Imports System.Collections.Specialized
Namespace bbControl
    Public Class LoginControl
        Inherits Control
        Implements IPostBackDataHandler, IPostBackEventHandler
        'Striche unter IPostBackDataHandler; Fehlermeldung:
        '"test.bbControl.Login" muss 'Overridable Overloads Function _
          LoadPostData(postDataKey
        'As String, postCollection As 
        ' System.Collections.Specialized.NameValueCollection) As
        'Boolean' für die Schnittstelle System.Web.UI.PostBackDataHandler' 
        ' implementieren.
        Private _UserName As String = ""
        Private _Password As String = ""
        Public Property UserName() As String
            Get
                Return _UserName
            End Get
            Set(ByVal Value As String)
                _UserName = Value
            End Set
        End Property
        Public Property Password() As String
            Get
                Return _Password
            End Get
            Set(ByVal Value As String)
                _Password = Value
            End Set
        End Property
        Public Event AuthSuccess As EventHandler
        Public Event AuthFailure As EventHandler
        Public Overridable Function LoadPostData(ByVal postDataKey As String, _
                ByVal values As NameValueCollection()) As Boolean _
                Implements IPostBackDataHandler.LoadPostData
            'Fehlermeldung bei IPostBackDataHandler.LoadPostData:
            'LoadPostData kann LoadPostData nicht implementieren, da keine 
            ' entsprechende
            'function auf der Schnittstelle IPostBackDataHandler vorhanden ist.
            Dim newValues As String = values(postDataKey)
            'Fehlermeldung values(postDataKey):
            'Der Wert des Typs 
            ' System.Collections.Specialized.NameValueCollection
            'kann nicht zu String konvertiert werden.
            'Hier habe ich schon überlegt ob dann nicht einfach .ToString reicht
            Dim Index As Integer = newValues.IndexOf(",")
            Dim newUserName As String = ""
            Dim newPassword As String = ""
 
            newUserName = (newValues.Substring(0, Index))
            newPassword = (newValues.Substring(Index + 1, newValues.Length - _
              Index - 1))
            If ((Not newUserName = UserName) Or _
                    (Not newPassword = _Password)) Then
                _UserName = newUserName
                _Password = newPassword
                Return True
            End If
        End Function
        Public Overridable Sub RaisePostDataChangeEvent() _
                Implements IPostBackDataHandler.RaisePostDataChangedEvent
        End Sub
        Public Overridable Sub RaisePostBackEvent(ByVal eventArgument _
                As String) Implements IPostBackEventHandler.RaisePostBackEvent
            If Me._UserName = "Benutzer" And Me._Password = "Geheim" Then
                RaiseEvent AuthSuccess(Me, EventArgs.Empty)
            Else
                RaiseEvent AuthFailure(Me, EventArgs.Empty)
            End If
        End Sub
        Protected Overrides Sub Render(ByVal writer As HtmlTextWriter)
            writer.Write("Benutzername: <input name=" & _
                    Me.UniqueID & _
                    " id = UserNameKey" & _
                    " type=text value=" & _
                    Me.UserName)
            writer.Write("Kennwort: <input name=" & _
                    Me.UniqueID & _
                    " id = Password" & _
                    " type=password")
            writer.Write("<input type=button " & _
                    "value=Abschicken OnClick=""jscript:" & _
                    Page.GetPostBackEventReference(Me) & _
                    """> ")
            writer.WriteLine("")
            writer.WriteLine("<br>")
            writer.WriteLine("<br>")
        End Sub
    End Class
End Namespace

If it was hard to code, it should be hard to read too.