enkripsi vernam

Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        plainteks.Text = ""

        kunci.Text = ""

        chiperteks.Text = ""

    End Sub

    Private Sub Btnenkripsi_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Btnenkripsi.Click

        Dim j As Integer

        Dim jum As Integer

        Dim sKey As String

        Dim nKata As Integer

        Dim nKunci As Integer

        Dim sKata As String

        Dim sPlain As String = ""

        Dim nEnc As Integer

        j = 0

        sKata = plainteks.Text

        jum = Len(sKata)

        sKey = kunci.Text

        For i = 1 To jum

            If j = Len(sKey) Then

                j = 1

            Else

                j = j + 1

            End If

            nKata = Asc(Mid(sKata, i, 1)) - 65

            nKunci = Asc(Mid(sKey, j, 1)) - 65

            nEnc = ((nKata + nKunci) Mod 26)

            sPlain = sPlain & Chr((nEnc) + 65)

        Next i

        chiperteks.Text = sPlain

    End Sub

    Private Sub kunci_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles kunci.KeyPress

        e.KeyChar = UCase(e.KeyChar)

        Dim tombol As Integer = Asc(e.KeyChar)

        If Not (((tombol >= 65) And (tombol <= 90)) Or (tombol = 8)) Then

            e.Handled = True

        End If

    End Sub

    Private Sub plainteks_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles plainteks.KeyPress

        e.KeyChar = UCase(e.KeyChar)

        Dim tombol As Integer = Asc(e.KeyChar)

        If Not (((tombol >= 65) And (tombol <= 90)) Or (tombol = 8)) Then

            e.Handled = True

        End If

    End Sub

End Class