METHODE DE CHIFFREMENT DE VIGENÈRE, CRYPTAGE (FONCTION)

Private Function Crypt(ByVal strChaine As String, blnCryptage As Boolean) As String
  Dim I, J, K As Integer
  Dim strCryptKey As String
  Dim strLettre As String
  Dim strKeyLettre As String
  Dim intLettre As Long
  Dim intKeyLettre As Long
  Dim strResultat As String
  
  If strChaine = "" Then
    Crypt = ""
    Exit Function
  End If
  
  strCryptKey = "chiffrement de Vigenere"
  
  For K = 0 To 10 Step 1
    strResultat = ""
    
    For I = 1 To Len(strChaine) Step 1
      strLettre = Mid(strChaine, I, 1)
      J = I
      Do While J > Len(strCryptKey)
        J = J - Len(strCryptKey)
      Loop
      strKeyLettre = Mid(strCryptKey, J, 1)
      intLettre = Asc(strLettre)
      intKeyLettre = Asc(strKeyLettre)
      
      If blnCryptage = True Then
        intLettre = intLettre + (intKeyLettre * Len(strChaine))
      Else
        intLettre = intLettre - (intKeyLettre * Len(strChaine))
      End If
      
      Do While intLettre > 255
        intLettre = intLettre - 255
      Loop
      Do While intLettre < 0
        intLettre = intLettre + 255
      Loop
      strResultat = strResultat & Chr(intLettre)
    Next I
    
    strChaine = strResultat
  Next K
  
  Crypt = strResultat
End Function

25 mars 2005 17:30:48 :

Modification selon les conseils de Jack