Private Sub Command1_Click()
Dim Schlüssel As Integer
Schlüssel = 12
Dim Klartext As String
Klartext = "zuverschluesselndertext"
Dim Buchstaben(9999) As String
Dim x As Integer
For x = 0 To Len(Klartext) - 1
Buchstaben(x) = Mid(Klartext, x + 1, 1)
Next
Dim Bytes(9999) As Byte
Dim i As Integer
i = 0
Do Until Buchstaben(i) = ""
Bytes(i) = Asc(Buchstaben(i))
Bytes(i) = Bytes(i) + Schlüssel
If Bytes(i) > 122 Then Bytes(i) = Bytes(i) - 26
i = i + 1
Loop
i = 0
Do Until Bytes(i) = 0
Buchstaben(i) = Chr(Bytes(i))
i = i + 1
Loop
MsgBox (Buchstaben(0) & Buchstaben(1) & Buchstaben(3) & Buchstaben(4) & _
  Buchstaben(5) & Buchstaben(6) & Buchstaben(7) & Buchstaben(8) & Buchstaben(9) _
  & Buchstaben(10))
End Sub