www.pudn.com > 020827_encryp.zip > clsSimpleXOR.cls

VERSION 1.0 CLASS 
BEGIN 
  MultiUse = -1  'True 
END 
Attribute VB_Name = "clsSimpleXOR" 
Attribute VB_GlobalNameSpace = False 
Attribute VB_Creatable = True 
Attribute VB_PredeclaredId = False 
Attribute VB_Exposed = False 
'SimpleXOR Encryption/Decryption Class 
'------------------------------------ 
' 
'Information concerning encryption using 
'XOR can be found at: 
'http://tuath.pair.com/docs/xorencrypt.html 
' 
'(c) 2000, Fredrik Qvarfort 
' 
Option Explicit 
 
Private m_Key() As Byte 
Private m_KeyLen As Long 
Private m_KeyValue As String 
 
Event Progress(Percent As Long) 
 
Public Sub EncryptFile(SourceFile As String, DestFile As String, Optional Key As String) 
 
  Dim Filenr As Integer 
  Dim ByteArray() As Byte 
   
  'Make sure the source file do exist 
  If (Not FileExist(SourceFile)) Then 
    Call Err.Raise(vbObjectError, , "Error in Skipjack EncryptFile procedure (Source file does not exist).") 
    Exit Sub 
  End If 
   
  'Open the source file and read the content 
  'into a bytearray to pass onto encryption 
  Filenr = FreeFile 
  Open SourceFile For Binary As #Filenr 
  ReDim ByteArray(0 To LOF(Filenr) - 1) 
  Get #Filenr, , ByteArray() 
  Close #Filenr 
   
  'Encrypt the bytearray 
  Call EncryptByte(ByteArray(), Key) 
 
  'If the destination file already exist we need 
  'to delete it since opening it for binary use 
  'will preserve it if it already exist 
  If (FileExist(DestFile)) Then Kill DestFile 
   
  'Store the encrypted data in the destination file 
  Filenr = FreeFile 
  Open DestFile For Binary As #Filenr 
  Put #Filenr, , ByteArray() 
  Close #Filenr 
 
End Sub 
Public Sub DecryptFile(SourceFile As String, DestFile As String, Optional Key As String) 
 
  Dim Filenr As Integer 
  Dim ByteArray() As Byte 
   
  'Make sure the source file do exist 
  If (Not FileExist(SourceFile)) Then 
    Call Err.Raise(vbObjectError, , "Error in Skipjack EncryptFile procedure (Source file does not exist).") 
    Exit Sub 
  End If 
   
  'Open the source file and read the content 
  'into a bytearray to decrypt 
  Filenr = FreeFile 
  Open SourceFile For Binary As #Filenr 
  ReDim ByteArray(0 To LOF(Filenr) - 1) 
  Get #Filenr, , ByteArray() 
  Close #Filenr 
   
  'Decrypt the bytearray 
  Call DecryptByte(ByteArray(), Key) 
 
  'If the destination file already exist we need 
  'to delete it since opening it for binary use 
  'will preserve it if it already exist 
  If (FileExist(DestFile)) Then Kill DestFile 
 
  'Store the decrypted data in the destination file 
  Filenr = FreeFile 
  Open DestFile For Binary As #Filenr 
  Put #Filenr, , ByteArray() 
  Close #Filenr 
 
End Sub 
 
Public Sub DecryptByte(ByteArray() As Byte, Optional Key As String) 
 
  'The same routine is used for encryption 
  'as well as decryption so why not reuse 
  'some code and make this class smaller 
  '(that is if it wasn't for all those damn 
  'comments ;)) 
  Call EncryptByte(ByteArray(), Key) 
   
End Sub 
Public Sub EncryptByte(ByteArray() As Byte, Optional Key As String) 
 
  Dim Offset As Long 
  Dim ByteLen As Long 
  Dim ResultLen As Long 
  Dim CurrPercent As Long 
  Dim NextPercent As Long 
   
  'Set the new key if one was provided 
  If (Len(Key) > 0) Then Me.Key = Key 
   
  'Get the size of the source array 
  ByteLen = UBound(ByteArray) + 1 
  ResultLen = ByteLen 
   
  'Loop thru the data encrypting it with 
  'simply XORŽing with the key 
  For Offset = 0 To (ByteLen - 1) 
    ByteArray(Offset) = ByteArray(Offset) Xor m_Key(Offset Mod m_KeyLen) 
   
    'Update the progress if neccessary 
    If (Offset >= NextPercent) Then 
      CurrPercent = Int((Offset / ResultLen) * 100) 
      NextPercent = (ResultLen * ((CurrPercent + 1) / 100)) + 1 
      RaiseEvent Progress(CurrPercent) 
    End If 
  Next 
   
  'Make sure we return a 100% progress 
  If (CurrPercent <> 100) Then RaiseEvent Progress(100) 
 
End Sub 
Public Function EncryptString(Text As String, Optional Key As String) As String 
 
  Dim a As Long 
  Dim ByteLen As Long 
  Dim ByteArray() As Byte 
   
  'Convert the source string into a byte array 
  ByteArray() = StrConv(Text, vbFromUnicode) 
   
  'Encrypt the byte array 
  Call EncryptByte(ByteArray(), Key) 
   
  'Return the encrypted data as a string 
  EncryptString = StrConv(ByteArray(), vbUnicode) 
   
End Function 
Public Function DecryptString(Text As String, Optional Key As String) As String 
 
  Dim a As Long 
  Dim ByteLen As Long 
  Dim ByteArray() As Byte 
   
  'Convert the source string into a byte array 
  ByteArray() = StrConv(Text, vbFromUnicode) 
   
  'Encrypt the byte array 
  Call DecryptByte(ByteArray(), Key) 
   
  'Return the encrypted data as a string 
  DecryptString = StrConv(ByteArray(), vbUnicode) 
   
End Function 
 
Public Property Let Key(New_Value As String) 
 
  'Do nothing if the key is buffered 
  If (m_KeyValue = New_Value) Then Exit Property 
   
  'Set the new key and convert it to a 
  'byte array for faster accessing later 
  m_KeyValue = New_Value 
  m_KeyLen = Len(New_Value) 
  m_Key() = StrConv(m_KeyValue, vbFromUnicode) 
   
End Property