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Posted on 2005-05-08
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I have written a VB.NET 2003 application which I would like to reduce the possibilities of people making illegal copies. Therefore, I wrote some code that when the program is run for the first time, it gererates a random code. The user must then e-mail or phone me and read this number to me. I then type it into a little program I wrote which performs some simple calculations on it and spits out another code. I then give this to the client to punches it into the program. The program performs the same calculation on the original number, and if it matches the number I gave him, it unlocks the program. It can even unlock the program for a certain number of days (basically extend the trial period) depending on what code I give him. Just two problems:

1. The trial number of days left / unlock status is stored in the registry and can therefore be modified my anyone with some Windows knowledge. What is the best way to encrypt this number?

2. Is there a program or code that does more or less what Windows XP Activation does - where instead of randomly generating a number when the program is run for the first time, it generates a number based on the user's hardware? That way I can tell if he is installing it on another machine if he phones trying to get another unlock key. Also, if he formats and reinstalls the program, the same unlock her from before will still work.

Thanks
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Question by:SETP
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by:oleggold
oleggold earned 450 total points
ID: 13954897
Hi SETP,
> generates a number based on the user's hardware
Try this:
http://www.freepatentsonline.com/4685055.html
Hope It helps
Cheers!
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by:amyhxu
amyhxu earned 450 total points
ID: 13954985
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by:
jarnsater earned 600 total points
ID: 14085481

I'm currently developing a piece of software that will do a hardware and software inventory of all computers, and what I've found best to use for secure identification is CPU id and BIOS id.

These can be retrieved by using WMI, as in my example below.
WMI is very powerful and can be used to get all available info about the computer.

Check here if you want to know about additional WMI classes available:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wmisdk/wmi/win32_classes.asp

Btw, the code below is VB6, but should easily be able to port it to .NET

/ Jon

---------------
'Add the following code to a module (called e.g. WMI)
Option Explicit

Private m_mainWmi As Object
Private m_deviceLists As Collection

Private Function GetMainWMIObject() As Object
  On Error GoTo eh
  If m_mainWmi Is Nothing Then
    Set m_mainWmi = GetObject("WinMgmts:")
  End If
  Set GetMainWMIObject = m_mainWmi
  Exit Function
eh:
  Set GetMainWMIObject = Nothing
End Function

Public Function WmiIsAvailable() As Boolean
  WmiIsAvailable = CBool(Not GetMainWMIObject Is Nothing)
End Function

Public Function GetWmiDeviceSingleValue(ByVal WmiClass As String, ByVal WmiProperty As String) As String
  On Error GoTo done
  Dim result As String
 
  Dim wmiclassObjList As Object
  Set wmiclassObjList = GetWmiDeviceList(WmiClass)
  Dim wmiclassObj As Object
  For Each wmiclassObj In wmiclassObjList
    result = CallByName(wmiclassObj, WmiProperty, VbGet)
    Exit For
  Next

done:
  GetWmiDeviceSingleValue = Trim(result)
End Function

Public Function GetWmiDeviceList(ByVal WmiClass As String) As Object
  If m_deviceLists Is Nothing Then
    Set m_deviceLists = New Collection
  End If
 
  On Error GoTo fetchNew
 
  Set GetWmiDeviceList = m_deviceLists.Item(WmiClass)
  Exit Function
 
fetchNew:
  Dim devList As Object
  Set devList = GetWmiDeviceListInternal(WmiClass)
  If Not devList Is Nothing Then
    Call m_deviceLists.Add(devList, WmiClass)
  End If
  Set GetWmiDeviceList = devList
End Function

Private Function GetWmiDeviceListInternal(ByVal WmiClass As String) As Object
  On Error GoTo eh
  Set GetWmiDeviceListInternal = GetMainWMIObject.Instancesof(WmiClass)
  Exit Function
eh:
  Set GetWmiDeviceListInternal = Nothing
End Function


------------------------------

' then anywhere in your program you could write the fllowing to get the id:s

  Dim CPU As String
  CPU = GetWmiDeviceSingleValue("Win32_Processor", "ProcessorID")
 
  Dim BIOS As String
  BIOS = GetWmiDeviceSingleValue("Win32_BIOS", "SerialNumber")
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