'angenommen dies seien Deine komischen Stringvariablen
  Dim a As String = "asdasdfdfße5045ß6945"
  Dim b As String = "2@²&//0---.... wewerw"
  Dim c As String = "éüä'''##+*+~~à"
 
  '.... zusammengefasst in einer Liste 
  Dim mydata As New List(Of String)
  mydata.Add(a) : mydata.Add(b) : mydata.Add(c)
 
  'Erstellung der Code-Tabelle aus den String-Zeichen
  Dim codetable As New List(Of Char)
  For Each serie As String In mydata
     For i = 0 To serie.Length - 1
         If Not codetable.Contains(serie(i)) Then codetable.Add(serie(i))
     Next i
  Next serie
 
  'Umwandlung der Strings jeweils in eine Liste von Bytefolgen
  Dim myCodeSeries As New List(Of List(Of Byte))
  Dim bytes() As Byte
  Dim cnt As Integer = -1
 
  For Each serie As String In mydata
      myCodeSeries.Add(New List(Of Byte))
      cnt += 1
      For i As Integer = 0 To serie.Length - 1
          'Die Codetabelle liefert den Ushort-Wert des Zeichens, 
          'der Bitconverter die beiden entsprechenden Bytes
          bytes = BitConverter.GetBytes(CUShort(codetable.IndexOf(serie(i))))
          myCodeSeries(cnt).Add(bytes(0))
          myCodeSeries(cnt).Add(bytes(1))
      Next i
  Next serie
 
 
  'Diese Bytefolgen können jetzt komprimiert werden
  '------------------------------------------------
 
  'Zurückverwandlung der dekomprimierten Byteserien in das Ausgangsmaterial
 
  Dim mydata2 As New List(Of String)
  cnt = -1
 
  For Each codeserie As List(Of Byte) In myCodeSeries
      cnt += 1
      mydata2.Add("")
      For i As Integer = 0 To codeserie.Count - 1 Step 2
         'Bitconvertert liefert Ushort-Wert zu den 2 Bytes, die Codetable das 
         ' Zeichen
         mydata2(cnt) &= 
         codetable(BitConverter.ToUInt16(New Byte() {codeserie(i), codeserie(i _
           + 1)}))
      Next i
  Next codeserie
 
 
  'Kontrolle  
  For i As Integer = 0 To mydata.Count - 1
      For k As Integer = 0 To mydata(i).Length - 1
          If mydata(i)(k) <> mydata2(i)(k) Then Stop
      Next k
  Next i