Search Tools Links Login

RC4 Class


Applys Encryption/Decryption to strings. I think just about everyone who has seen my code knows how I love classes. This version is more "cleaned up" and thrown into a nice little class for an object oriented feeling. (If only ASP was object oriented, I would be a happy camper). It is also a little more optimized to run quicker if you change the Key/Password often.

Original Author: Lewis E. Moten III

Code

<%
Option Explicit
Dim ObjRC4
Set ObjRC4 = New clsRC4
ObjRC4.Key = "Joe"
Response.Write """" & ObjRC4.Crypt("hello") & """"
Set ObjRC4 = Nothing
' ------------------------------------------------------------------------------
Class clsRC4

Private mStrKey
Private mBytKeyAry(255)
Private mBytCypherAry(255)

Private Sub InitializeCypher()

Dim lBytJump
Dim lBytIndex
Dim lBytTemp

For lBytIndex = 0 To 255
  mBytCypherAry(lBytIndex) = lBytIndex
Next
' Switch values of Cypher arround based off of index and Key value
lBytJump = 0
For lBytIndex = 0 To 255

' Figure index to switch
  lBytJump = (lBytJump + mBytCypherAry(lBytIndex) + mBytKeyAry(lBytIndex)) Mod 256
  
  ' Do the switch
  lBytTemp = mBytCypherAry(lBytIndex)
  mBytCypherAry(lBytIndex) = mBytCypherAry(lBytJump)
  mBytCypherAry(lBytJump) = lBytTemp
  
Next
End Sub

Public Property Let Key(ByRef pStrKey)
Dim lLngKeyLength
Dim lLngIndex

If pStrKey = mStrKey Then Exit Property
lLngKeyLength = Len(pStrKey)
If lLngKeyLength = 0 Then Exit Property
mStrKey = pStrKey
lLngKeyLength = Len(pStrKey)
For lLngIndex = 0 To 255
  mBytKeyAry(lLngIndex) = Asc(Mid(pStrKey, ((lLngIndex) Mod (lLngKeyLength)) + 1, 1))
Next
End Property

Public Property Get Key()
Key = mStrKey
End Property
Public Function Crypt(ByRef pStrMessage)
Dim lBytIndex
Dim lBytJump
Dim lBytTemp
Dim lBytY
Dim lLngT
Dim lLngX

' Validate data
If Len(mStrKey) = 0 Then Exit Function
If Len(pStrMessage) = 0 Then Exit Function
Call InitializeCypher()

lBytIndex = 0
lBytJump = 0
For lLngX = 1 To Len(pStrMessage)
  lBytIndex = (lBytIndex + 1) Mod 256 ' wrap index
  lBytJump = (lBytJump + mBytCypherAry(lBytIndex)) Mod 256 ' wrap J+S()
  
' Add/Wrap those two   
  lLngT = (mBytCypherAry(lBytIndex) + mBytCypherAry(lBytJump)) Mod 256
  
  ' Switcheroo
  lBytTemp = mBytCypherAry(lBytIndex)
  mBytCypherAry(lBytIndex) = mBytCypherAry(lBytJump)
  mBytCypherAry(lBytJump) = lBytTemp
  lBytY = mBytCypherAry(lLngT)
' Character Encryption ...  
  Crypt = Crypt & Chr(Asc(Mid(pStrMessage, lLngX, 1)) Xor lBytY)
Next

End Function
End Class
%>

About this post

Posted: 2002-06-01
By: ArchiveBot
Viewed: 97 times

Categories

ASP/ HTML

Attachments

No attachments for this post


Loading Comments ...

Comments

No comments have been added for this post.

You must be logged in to make a comment.