LDAP - Authentifizieren eines Benutzers in der Domäne

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Imports System.Security
Imports System.DirectoryServices
Imports System.DirectoryServices.ActiveDirectory

Public Shared Function Authenticate(ByVal domain As String, ByVal username As String, ByVal password As String) As Boolean 
    Dim pwd As New SecureString() 
    Dim bAuth As Boolean = False 
    Dim entry As DirectoryEntry = Nothing 
    
    'Durchlaufe das Passwort und hänge es dem SecureString an 
    For Each c As Char In password 
        pwd.AppendChar(c) 
    Next 
    
    'Bewirkt, dass das Passwort nicht mehr verändert werden kann 
    pwd.MakeReadOnly() 
    
    'Passwort wird einem Pointer übergeben, damit dieser später "entschlüsselt" werden kann 
    Dim pPwd As IntPtr = System.Runtime.InteropServices.Marshal.SecureStringToBSTR(pwd) 
    
    Try 
        entry = New DirectoryEntry(String.Concat("LDAP://", domain), username, System.Runtime.InteropServices.Marshal.PtrToStringBSTR(pPwd)) 
        Dim nativeObject As Object = entry.NativeObject 
        bAuth = True 
    Catch ex As Exception 
        bAuth = False 
    Finally 
        entry.Close() 
        entry.Dispose() 
    End Try 
    Return bAuth 
End Function