BUILDER

Imports System.Text

Public Class Form1
    Const filesplit = "123456789"

    Private Sub jouvre_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles jouvre.Click
        Dim x As New OpenFileDialog 'simule une open file dialog
        x.Filter = "Exécutables |*.exe" 'nous indique quel fichier peut être séléctionné ici uniquement les éxecutables
        x.InitialDirectory = "/VotreDossier" 'le répertoire de départ lorsque la boite de dialogue s'affichera
        x.Multiselect = False 'séléctionner plusieurs fichiers ? Dans notre cas non laissez sur "False"
        If x.ShowDialog = Windows.Forms.DialogResult.OK Then ' si on clique sur "OK"
            emplacement.Text = x.FileName 'la textebox emplacement affiche où ce situe notre fichier à crytper.
        Else 'si aucune action ne s'éxécute (exemple : on ne séléctionne pas de fichier)
            MsgBox("Vous n'avez pas ouvert de fichier !") 'affiche message
            jecrytpe.Enabled = False 'le bouton crypter ne devient plus utilisable
            emplacement.Text = "aucun fichier !" 'la textbox "emplacement" nous affiche qu'il n'y a aucun fichier

        End If ' fin de la réponse
    End Sub







    Public Function RC4(ByVal message As String, ByVal password As String) As String

        Dim i As Integer = 0
        Dim j As Integer = 0
        Dim cipher As New StringBuilder
        Dim returnCipher As String = String.Empty

        Dim sbox As Integer() = New Integer(256) {}
        Dim key As Integer() = New Integer(256) {}

        Dim intLength As Integer = password.Length

        Dim a As Integer = 0
        While a <= 255

            Dim ctmp As Char = (password.Substring((a Mod intLength), 1).ToCharArray()(0))

            key(a) = Microsoft.VisualBasic.Strings.Asc(ctmp)
            sbox(a) = a
            System.Math.Max(System.Threading.Interlocked.Increment(a), a - 1)
        End While

        Dim x As Integer = 0

        Dim b As Integer = 0
        While b <= 255
            x = (x + sbox(b) + key(b)) Mod 256
            Dim tempSwap As Integer = sbox(b)
            sbox(b) = sbox(x)
            sbox(x) = tempSwap
            System.Math.Max(System.Threading.Interlocked.Increment(b), b - 1)
        End While

        a = 1

        While a <= message.Length

            Dim itmp As Integer = 0

            i = (i + 1) Mod 256
            j = (j + sbox(i)) Mod 256
            itmp = sbox(i)
            sbox(i) = sbox(j)
            sbox(j) = itmp

            Dim k As Integer = sbox((sbox(i) + sbox(j)) Mod 256)

            Dim ctmp As Char = message.Substring(a - 1, 1).ToCharArray()(0)

            itmp = Asc(ctmp)

            Dim cipherby As Integer = itmp Xor k

            cipher.Append(Chr(cipherby))
            System.Math.Max(System.Threading.Interlocked.Increment(a), a - 1)
        End While

        returnCipher = cipher.ToString
        cipher.Length = 0

        Return returnCipher

    End Function





























    Private Sub jecrytpe_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles jecrytpe.Click
        Dim filein, filename, stub As String
        Dim sfd As New SaveFileDialog
        sfd.Filter = "Exécutables |*.exe "
        If sfd.ShowDialog = Windows.Forms.DialogResult.OK Then

            filename = sfd.FileName


        Else : Exit Sub
        End If
        FileOpen(1, emplacement.Text, OpenMode.Binary, OpenAccess.Read, OpenShare.Default)
        filein = Space(LOF(1))
        FileGet(1, filein)
        FileClose(1)
        FileOpen(1, Application.StartupPath & "\Stub.exe", OpenMode.Binary, OpenAccess.Read, OpenShare.Default)
        stub = Space(LOF(1))
        FileGet(1, stub)

        FileClose(1)
        FileOpen(1, filename, OpenMode.Binary, OpenAccess.ReadWrite, OpenShare.Default)
        FilePut(1, stub & filesplit & RC4(filein, "123456789"))
        FileClose(1)
        MsgBox("le fichier a été crypté")


    End Sub

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

    End Sub
End Class