Write a simple encryption and decryption class with ASP ....

Encryption | Decrypt class Base64class
REM Const
Dim sbase_64_characters ' Conversion Code
Dim lenstring ' Computes the length of a string
Dim icount ' Counter
Dim ReturnValue ' return Value
Dim Tempchar ' Cached characters
Dim tempstring ' Cached String
Dim paramstring ' Parameter String
Dim Temhex ' Cache Cache hex
Dim Templow ' Cache Low
Dim Temphigh ' Cache High
Dim mod3string '
Dim mod4string '
Dim Tempbinary '
Dim Tempbyteone '
Dim Tempbytetwo '
Dim Tempbytethree '
Dim Tempbytefour '
Dim Tempsavebitsone '
Dim Tempsavebitstwo '
'********************************************
' Begin initializing Class
'********************************************
Private Sub Class_Initialize ()
Sbase_64_characters = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz0123456789+/" End Sub
'********************************************
' End Initialization class '
********************************************

'********************************************
' Begin destroying class
'********************************************
Private Sub Class_Terminate ()
Sbase_64_characters= "" End Sub
'********************************************
' End Destroy class
'********************************************

'********************************************
' Begin BASE64 encoding an ANSI-encoded string
'********************************************
Public Function Encode (paramstring)
Tempstring= ""
Returnvalue= ""
Lenstring=len (paramstring)
If Lenstring<1 Then
Encode=returnvalue
Else
Mod3string=lenstring MoD 3
' The number of complements is for ease of calculation.
If Mod3string>0 Then
Lenstring=lenstring+3-mod3string
Lenstring=lenstring-3
End If
' *************************begin
For Icount=1 to lenstring step 3
Tempbinary = Mid (paramstring, icount, 3)
' Response.Write tempbinary
Tempbyteone= ASC (Mid (tempbinary, 1, 1)): Tempsavebitsone = Tempbyteone and 3
Tempbytetwo = ASC (Mid (Tempbinary, 2, 1)): Tempsavebitstwo = Tempbytetwo and 15
Tempchar = ASC (Mid (Tempbinary, 3, 1))
Tempbyteone = Mid (Sbase_64_characters, (Tempbyteone and 252) \ 4) + 1, 1)
Tempbytetwo = Mid (Sbase_64_characters, (Tempbytetwo and R) and &AMP;HFF) + 1, 1)
Tempbytethree = Mid (Sbase_64_characters, (Tempchar and) Or (Tempsavebitstwo * 4) and &AMP;HFF) + 1, 1)
Tempbytefour = Mid (Sbase_64_characters, (Tempchar and 63) + 1, 1)
tempstring = Tempbyteone & tempbytetwo & tempbytethree & tempbytefour Returnvalue=returnvalue & TempStrin G Next
' *************************end
' *************************begin processing the last remaining few characters
If Mod3string>0 Then
Tempbinary = Mid (paramstring, icount, mod3string)
If Mod3string=1 Then
tempstring = tempbinary & Chr ($) & Chr ($) & CHR (64) ' with the @ number of digits
else tempstring = tempbinary & Chr ($) & CHR (64) ' complement digits with @
End If
Returnvalue=returnvalue & TempString
End If
' *************************end processing the last remaining few characters
Encode=returnvalue End If End function
'********************************************
' End BASE64 encoding an ANSI-encoded string
'********************************************

'********************************************
' End converts a Base64 encoded string into an ANSI-encoded string
'********************************************
Public Function Decode (paramstring)
Tempstring= ""
Returnvalue= ""
Lenstring=len (paramstring)
If Lenstring<1 Then
Decode=returnvalue
Else
Mod4string=lenstring MoD 4
If mod4string >0 then ' string length should be a multiple of 4
Decode=returnvalue
Else ' begin to judge whether the @ number
If Mid (paramstring, lenString-1, 1) = "@" Then
mod4string=2
End If
If Mid (paramstring, lenString-2, 1) = "@" Then
Mod4string=1
End If
' End judgment is not the @ number
If Mod4string>0 Then
Lenstring=lenstring-4
End If
' ******************************begin
For Icount=1 to lenstring step 4
tempstring = Mid (paramstring, icount, 4)
Tempbyteone = InStr (Sbase_64_characters, Mid (tempstring, 1, 1))-1
Tempbytetwo = InStr (Sbase_64_characters, Mid (tempstring, 2, 1))-1
Tempbytethree = InStr (Sbase_64_characters, Mid (tempstring, 3, 1))-1
Tempbytefour = InStr (Sbase_64_characters, Mid (tempstring, 4, 1))-1
Tempbyteone = Chr ((tempbytetwo) or (Tempbyteone * 4) and &AMP;HFF) Tempbytetwo = "" & Chr ((Tempbytethre E and) \ 4) Or (Tempbytetwo *) and &AMP;HFF)
Tempbytethree = Chr ((Tempbytethree and 3) *) and &AMP;HFF) Or (Tempbytefour and