Dim aa As String * 1
    Dim aa2 As String * 1
    Dim DNr As Integer
    Dim j As Long
 
    DNr = FreeFile
    Open "C:\datei.txt" For Random As #DNr Len = 1
    j = 1
    Randomize Rnd(-1)
    Randomize 1 'entspricht dem Passwort
    Do
      Get #DNr, j, aa
      If Not EOF(DNr) Then
        aa2 = Chr(Asc(aa) Xor ((Rnd * 255) \ 1))
        Put #DNr, j, aa2
      End If
      j = j + 1
    Loop Until EOF(DNr)
 
    Close #DNr
 
    MsgBox "Fertig"