Excel workbook copy protection
Excel workbook copy protection is required when you are going to license and distribute your spreadsheet to a customer and want to avoid illegal copying or illegal usage of your intellectual property.
The term “copy protection” does not mean that a protected Excel file cannot be copied from one computer to another.
Workbook copy protection means that author of the protected workbook will be able to give permission to use the application on a specific computer. Without such permission, the protected workbook will not start.
The first, and most important, prerequisite for Excel spreadsheet copy protection is the inaccessibility of cell formulas in the spreadsheet. This is ensured by the compilation of all cell formulas in the workbook into binary code and their removal from the spreadsheet’s cells.
In the DoneEx XCell Compiler, the Excel workbook copy protection is implemented by tying the compiled workbook (EXE file) to the registration key with the information about the target computer. When compiled workbook is started, it checks if that customer has enough permissions to use the workbook on the computer.
The registration/activation key (regkey) is an encrypted file. It contains all registration information about the registered customer, company, and the target computer where that regkey allows the compiled EXE to be started.
The registration key uses a computer id number to identify the target computer. The Computer ID is created from unique hardware and software information of the computer and is used to identify that computer. It is impossible for there to be 2 identical computer IDs for 2 different computers.
How the workbook copy protection works
1. You compile the EXE file with the hardware locking option selected, then put it on web for downloading or send this EXE to your client some other way.
2. Your client tries to start this EXE file, sees the window that contains only his computer id number and sends this number to you.
3. You generate the registration key using your client’s registration info (name, email, etc) along with their computer id number, and send it to your client (after they made purchase, for example).
4. Your client copies the registration key into the same folder as where the EXE is located.
5. The EXE starts only on that computer.
Main stages of the workbook copy protection process
Step 1. Workbook compilation with copy protection options
The compilation options that are relevant to copy protection are marked in the above image.
Hardware locking option should be enabled.
Application name creates an internal link between compiled EXE and registration key file (regkey).
The compiled EXE file will search for the regkey file by the name which you enter in the ‘Registration key file name’ field.
Step 2. Request for customer’s computer ID
When your customer receives the compiled EXE for the first time (without a regkey), they cannot run the application.
After trying to start the EXE they only can see the following message:
Step 3. Creation of the registration/activation key.
After you have created the registration key file, you need to send it to your customer. The customer copies the regkey file into the folder with the protected workbook and, in doing so, unlocks the workbook. From this moment, the customer allowed to use the protected workbook.