Imports System.Security.Cryptography
Imports System.Text
 
Module Module1
 
  ''' <summary>
  ''' Beliebiges zusätzliches Byte-Array, um die Sicherheit zu erhöhen.
  ''' </summary>
  Private ReadOnly Zus As Byte() = {17, 114, 32, 97, 144, 84, 8, 206, 12, 78}
 
  ''' <summary>
  ''' Verschlüsselt einen String und liefert ein Byte-Array.
  ''' </summary>
  Friend Function Verschlüsseln(data As String) As Byte()
    Try
      Dim ba As Byte() = Encoding.Default.GetBytes(data)
      Return ProtectedData.Protect(ba, Zus, DataProtectionScope.CurrentUser)
    Catch ex As Exception
      Return Nothing
    End Try
  End Function
 
  ''' <summary>
  ''' Entschlüsselt ein Byte-Array und liefert den originalen String.
  ''' </summary>
  Friend Function Entschlüsseln(data As Byte()) As String
    Try
      Dim ba As Byte() = ProtectedData.Unprotect(data, Zus, _
        DataProtectionScope.CurrentUser)
      Return Encoding.Default.GetString(ba)
    Catch ex As CryptographicException
      MsgBox(ex.Message, MsgBoxStyle.Critical)
    End Try
    Return String.Empty
  End Function
 
End Module