enkripsi text vb.net

Vigenere Cipher

Public Class Form1
    Dim huruf(26) As Char
    Dim i, p, k, c As Integer
    Dim plainText, cipherText As String

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        ' Mengisi array abjad A s/d Z, Kode ASCII A=65
        For i = 0 To 25
            huruf(i) = Chr(65 + i)
        Next i
    End Sub

    Private Sub ButtonEncrypt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonEncrypt.Click
        cipherText = ""
        k = CInt(TextBoxGeser.Text)
        If (TextBoxPlain.Text.Length <> 0) Then
            For i = 0 To TextBoxPlain.Text.Length - 1
                p = Asc(TextBoxPlain.Text.Substring(i, 1)) - 65
                c = (p + k) Mod 26
                cipherText = String.Concat(cipherText, huruf(c))
            Next i
            TextBoxCipher.Text = cipherText
        End If
    End Sub

    Private Sub ButtonDecrypt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonDecrypt.Click
        Dim geserKiri As Integer
        plainText = ""
        k = CInt(TextBoxGeser.Text)
        geserKiri = 26 - (k Mod 26)
        If (TextBoxCipher.Text.Length <> 0) Then
            For i = 0 To TextBoxCipher.Text.Length - 1
                c = Asc(TextBoxCipher.Text.Substring(i, 1)) - 65
                p = (c + geserKiri) Mod 26
                plainText = String.Concat(plainText, huruf(p))
            Next i
            TextBoxPlain2.Text = plainText
        End If
    End Sub

Poly Alphabetic Cipher

Public Class Form1
    Dim huruf(26) As Char
    Dim i, p, k, c As Integer
    Dim plainText, cipherText As String
    Dim kunci As String

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        ' Mengisi array abjad A s/d Z, Kode ASCII A=65
        For i = 0 To 25
            huruf(i) = Chr(65 + i)
        Next i
    End Sub


    Private Sub ButtonEncrypt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonEncrypt.Click
        cipherText = ""
        If (TextBoxPlain.TextLength <> 0 And TextBoxKunci.TextLength <> 0) Then
            aturKunci()
            For i = 0 To TextBoxPlain.TextLength - 1
                p = Asc(TextBoxPlain.Text.Substring(i, 1)) - 65
                k = Asc(kunci.Substring(i, 1)) - 65
                c = (p + k) Mod 26
                cipherText = String.Concat(cipherText, huruf(c))
            Next i
            TextBoxCipher.Text = cipherText
        End If
    End Sub

    Private Sub ButtonDecrypt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonDecrypt.Click
        plainText = ""
        If (TextBoxCipher.TextLength <> 0 And TextBoxKunci.TextLength <> 0) Then
            aturKunci()
            For i = 0 To TextBoxCipher.TextLength - 1
                c = Asc(TextBoxCipher.Text.Substring(i, 1)) - 65
                k = Asc(kunci.Substring(i, 1)) - 65
                p = (c + 26 - k) Mod 26
                plainText = String.Concat(plainText, huruf(p))
            Next i
            TextBoxPlain2.Text = plainText
        End If
    End Sub

    Private Sub TextBoxPlain_GotFocus(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBoxPlain.GotFocus
        TextBoxPlain.SelectAll()
    End Sub

    Private Sub TextBoxPlain_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBoxPlain.KeyPress
        e.Handled = Not (Char.IsLetter(e.KeyChar) Or Asc(e.KeyChar) < 32)
        e.KeyChar = UCase(e.KeyChar)
    End Sub

    Private Sub TextBoxPlain_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBoxPlain.TextChanged
        TextBoxCipher.Text = ""
    End Sub

    Private Sub TextBoxCipher_GotFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBoxCipher.GotFocus
        TextBoxCipher.SelectAll()
    End Sub

    Private Sub TextBoxCipher_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBoxCipher.KeyPress
        e.Handled = Not (Char.IsLetter(e.KeyChar) Or Asc(e.KeyChar) < 32)
        e.KeyChar = UCase(e.KeyChar)
    End Sub

    Private Sub TextBoxCipher_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBoxCipher.TextChanged
        TextBoxPlain2.Text = ""
    End Sub

    Private Sub TextBoxKunci_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBoxKunci.KeyPress
        e.Handled = Not (Char.IsLetter(e.KeyChar) Or Asc(e.KeyChar) < 32)
        e.KeyChar = UCase(e.KeyChar)
    End Sub

    Private Sub aturKunci()
        If TextBoxPlain.Text.Length <= TextBoxKunci.Text.Length Then
            kunci = TextBoxKunci.Text.Substring(0, TextBoxPlain.TextLength)
        Else
            kunci = ""
            For i = 1 To (TextBoxPlain.TextLength / TextBoxKunci.TextLength)
                kunci = String.Concat(kunci, TextBoxKunci.Text)
            Next i
            i = TextBoxPlain.TextLength Mod TextBoxKunci.TextLength
            If i > 0 Then
                kunci = String.Concat(kunci, TextBoxKunci.Text.Substring(0, i))
            End If
        End If
    End Sub

End Class