Kriptografi Sederhana

Selamat pagi sobat blogger, pada pagi yang sangat cerah ini, saya akan berbagi ilmu sedikit tentang kriptografi, tapi kriptografi itu apa yaaa.... !

Kriptografi (cryptography) berasal dari bahasa

Yunani, terdiri dari dua suku kata yaitu kripto dan graphia. Kripto artinya menyembunyikan, sedangkan graphia artinya tulisan. Kriptografi adalah ilmu yang mempelajari teknik-teknik matematika yang berhubungan dengan aspek keamanan informasi, seperti kerahasiaan data, keabsahan data, integritas data, serta autentikasi data .Tetapi tidak semua aspek keamanan informasi dapat diselesaikan dengan kriptografi. Kriptografi dapat pula diartikan sebagai ilmu atau seni untuk menjaga keamanan pesan.

Pada prinsipnya, Kriptografi memiliki 4 komponen utama yaitu:

1.     Plaintext, yaitu pesan yang dapat dibaca

2.     Ciphertext, yaitu pesan acak yang tidka dapat dibaca

3.     Key, yaitu kunci untuk melakukan teknik kriptografi

4.     Algorithm, yaitu metode untuk melakukan enkrispi dan dekripsi

Kemudian, proses yang akan dibahas dalam artikel ini meliputi 2 proses dasar pada Kriptografi yaitu:

1.     Enkripsi (Encryption)

2.     Dekripsi (Decryption)

Nah... dalam postingan kali ini, ada 4 kriptografi yang akan kita bahas yaitu, Kriptografi ceesar, kriptografi vernam, kriptografi groundsfield dan kriptografi vegenere, yang masing masing mempunyai maksud yg sama yaitu untuk mengaman kan data.

Ok... langsung saja, kita masuki kriptografi pertama

   A.    Kriptografi ceesar

ketikkan listing berikut:

Add caption

Public Class Kriptografi_Caesar

    Private Sub btnenkripsi_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnenkripsi.Click

        Dim x As String = ""

        Dim xkalimat As String = ""

        For i = 1 To Len(plaint.Text)

            x = Mid(plaint.Text, i, i)

            x = Chr(Asc(x) + 3)

            xkalimat = xkalimat + x

        Next

        chiper.Text = xkalimat

    End Sub

    Private Sub btndeskripsi_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btndeskripsi.Click

        Dim a As String = ""

        Dim akalimat As String = ""

        For i = 1 To Len(plaint.Text)

            a = Mid(plaint.Text, i, i)

            a = Chr(Asc(a) - 3)

            akalimat = akalimat + a

        Next

        chiper.Text = akalimat

    End Sub

End Class

   B.      Kriptografi vernam

ketikak listing berikut:

Public Class Kriptografi_vernam

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

        plainteks.Text = ""

        DDD.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 splaint As String = ""

        Dim nenc As Integer

        j = 0

        skata = plainteks.Text

        jum = Len(skata)

        skey = DDD.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, i, 1)) - 65

            nenc = ((nkata + nkunci) Mod 26)

            splaint = splaint & Chr((nenc) + 65)

        Next i

        chiperteks.Text = splaint

    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

    Private Sub kunci_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles DDD.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 btn_deskripsi_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn_deskripsi.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 splaint As String = ""

        Dim nenc As Integer

        j = 0

        skata = plainteks.Text

        jum = Len(skata)

        skey = DDD.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, i, 1)) - 65

            nenc = ((nkata + nkunci) Mod 26)

            splaint = splaint & Chr((nenc) + 65)

        Next i

        chiperteks.Text = splaint

    End Sub

End Class

   C.      Kriptografi ground sfield

 ketikkan listing berikut;

 Public Class Kriptografi_Gronsfield

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

        plainteks.Text = ""

        DDD.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 splaint As String = ""

        Dim nenc As Integer

        j = 0

        skata = plainteks.Text

        jum = Len(skata)

        skey = DDD.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)) - 48

            nenc = ((nkata + nkunci) Mod 26)

            splaint = splaint & Chr((nenc) + 65)

        Next i

        chiperteks.Text = splaint

    End Sub

    Private Sub btn_deskripsi_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn_deskripsi.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 splaint As String = ""

        Dim nenc As Integer

        j = 0

        skata = plainteks.Text

        jum = Len(skata)

        skey = DDD.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, i, 1)) - 48

            nenc = ((nkata + nkunci) Mod 26)

            splaint = splaint & Chr(nenc - 65)

        Next i

        chiperteks.Text = splaint

    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

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

        e.KeyChar = UCase(e.KeyChar)

        Dim tombol As Integer = Asc(e.KeyChar)

        If Not ((e.KeyChar >= "0" And e.KeyChar <= "9") Or e.KeyChar = vbBack) Then

            e.Handled = True

        End If

    End Sub

End Class

   D.      Kriptografi vegenere

Cara mainnya adalah

Public Class Kriptografi_Vigenere

    Function Enkripsi(ByVal Teks As String, ByVal Kunci As String) As String

        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

        jum = Len(Teks)

        sPlain = ""

        sKey = Kunci

        sKata = Teks

        For i = 1 To jum

            If j = Len(sKey) Then

                j = 1

            Else

                j = j + 1

            End If

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

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

            nEnc = ((nKata + nKunci) Mod 256)

            sPlain = sPlain & Chr((nEnc))

        Next i

        Enkripsi = sPlain

    End Function

    Private Sub btnenkripsi_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnenkripsi.Click

        chipertext.Text = Enkripsi(plaintext.Text, kunci.Text)

    End Sub

End Class

sekian dulu ya gan... moga bermanfaat buat kita semua, dan baca juga tentang program Pembayaran Listrik Menggunakan VB.2008.