CRYPTAGE XOR +PRINCIPE DE VIGENERE

Private Sub Commande12_Click()
'**********************decryptage clé fixe***********************
Dim i, chainecrypt, chainedecrypt, decrypt, cpt
cpt = 0
For i = 1 To Len(cryptf) Step 3
cpt = cpt + 1
    chainecrypt = Mid(cryptf, i, 3)
    chainedecrypt = (chainecrypt Xor Asc(Mid(cle, cpt, 1)))
    decrypt = decrypt & Chr(chainedecrypt)
Next i
Texte10 = decrypt
End Sub

Private Sub Commande9_Click()
'********************cryptage avec xor et clé fixe***************
Dim inptext, char, longtext, i, c, j, val_max, var_cle
Dim nmbr As Integer
Dim var_char, val_debut_cle As String

cle = "abc"

inptext = InputBox("entrez le text a crypter")
longtext = Len(inptext)
val_debut_cle = cle

'--egalisation de la longueur de la clé et celle des données--
val_max = Int(((longtext / Len(val_debut_cle)) - 1))
For c = 1 To val_max
    cle = cle & val_debut_cle
Next c

j = longtext - Len(cle)
cle = cle & Left(cle, j)
'---------------------fin de l'égalisation--------------------
    
For i = 1 To longtext
    var_char = Mid(inptext, i, 1)
    var_cle = Asc(Mid(cle, i, 1))
    char = Asc(var_char)
    crypt = (var_cle Xor char)
        
        If Len(crypt) < 2 Then 'ajout de 0 pour combler les vides
        crypt = "0" & crypt
        End If
        If Len(crypt) < 3 Then
        crypt = "0" & crypt
        End If
              
        If Not i = 1 Then
        cryptf = cryptf & crypt
        Else
        cryptf = crypt
        End If
Next i

MsgBox ("Cryptage = " & cryptf)
End Sub