Write a simple encryption and decryption class with ASP

Encryption | decryption

Using ASP to write a simple encryption and decryption class, in this class simple implementation of a cryptographic and decryption. The purpose is to share with you. The cracking of this class is very simple. Just look at my notes and see what's going on. The next time you write a Java encryption and decryption class. 　　 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 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 63)) Tempstring=tempbyteone & Tempbytetwo & Tempbytethree Returnvalue=returnvalue & TempString Next ' ******************************end ' Handle the last remaining few characters If mod4string > 0 Then Tempstring=left (Right (paramstring,4), mod4string) returnvalue = returnvalue & tempstring End If Decode=returnvalue End If End If End Function '******************************************** ' End converts a Base64 encoded string into an ANSI-encoded string '******************************************** End Class