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Encrypting Cookie Text

Written by Eric Smith, Northstar Computer Systems LLC

If you've ever looked at cookie contents, you will see that the text is stored in plain text format. If you have a need to store sensitive information in a cookie and don't want people to be able to easily read it, use a simple encryption/decryption technique. This code uses the ASCII values of the characters and separates them by dashes. The ASCII values are incremented by 10 to make it a bit more complicated.
Private Function Encrypt(strOriginal)
   Dim strNew ' As String
   Dim i	' As Integer
   
   For i = 1 To Len(strOriginal)
      If strNew <> "" Then
         strNew = strNew & "-"
      End If
      strNew = strNew & _
         Asc(Mid(strOriginal, i, 1)) + 20
      
   Next ' i
   Encrypt = strNew
   
End Function

For 'This is a test', the resulting value is this:
104-124-125-135-52-125-135-52-117-52-136-121-135-136

To decrypt the text, you would use this function:

Private Function Decrypt(strEncrypted)
   Dim strNew 'As String
   Dim a_strCharacters() 'As String
   Dim i ' As Integer
   
   a_strCharacters = _
      Split(strEncrypted, "-")
   For i = 0 To UBound(a_strCharacters)
      strNew = strNew & _
         Chr(CInt(a_strCharacters(i)) - 20)
   Next ' i
   
   Decrypt = strNew
   
End Fu
nction

Keywords: [ Uncategorized ASP Tips ]

Publication Date: 6/1/2000