Function Do_rot(rng As Range, str As String)
Dim r As Range
Dim iTemp As Integer, sTEmp As String
Dim i As Integer
For i = 1 To Len(str)
Set r = rng
With r.Find
.Text = Mid(str, i, 1)
.Font.Color = wdColorBlack
iTemp = (i + 13) Mod Len(str)
If iTemp = 0 Then iTemp = Len(str)
sTEmp = Mid(str, iTemp, 1)
.Replacement.Text = sTEmp
.Replacement.Font.Color = wdColorRed
.MatchCase = True
.Execute Replace:=wdReplaceAll
End With
Next i
End Function