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
%>
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