Public Class EncryptionForm

   ' using the substitution cipher
   Private Sub SubstitutionCipher()

      ' normal alphabet String
      Dim normalAlphabet As String = _
         "abcdefghijklmnopqrstuvwxyz .!?,"

      ' substitution alphabet String
      Dim cipherAlphabet As String = _
         "cdefg.hijk!lmn opqr?stuv,wxyzab"

      Dim index1 As Integer ' index variable for For...Next loop
      Dim index2 As Integer ' inner index variable
      Dim plain As String = plainTextBox.Text ' String entered by the user
      Dim cipher As String ' encrypted String

      cipherTextLabel.Text = "" ' clear output TextBox
      plain = plain.ToLower() ' make characters lowercase

      For index1 = 0 To 30 ' go through string for normal alphabet
         plain = normalAlphabet.Chars(index1)

         For index2 = 0 To 30 ' go through string for cipher alphabet
            cipher = cipherAlphabet.Chars(index2) ' new string = new character
            cipher &= cipherAlphabet(index2) ' append character to string
         Next
         cipherTextLabel.Text = cipher ' output new string to label
      Next
   End Sub ' SubstitutionCipher

   ' using the transposition cipher
   Private Sub TranspositionCipher()

      Dim counter As Integer = 0 'loop counter variable
      Dim input As String = plainTextBox.Text ' input word by user
      Dim output As String ' changed word

      Do While counter <= 30
         counter = +2

      Loop

   End Sub ' TranspositionCipher

   Private Sub encryptButton_Click(ByVal sender As System.Object, _
   ByVal e As System.EventArgs) Handles encryptButton.Click

      If substitutionRadioButton.Checked = True Then 'if substitution radio button checked
         SubstitutionCipher() ' goto function
      Else
         TranspositionCipher() ' if transposition radio button checked goto function
      End If
   End Sub
End Class ' EncryptionForm