how to secure an excel file so that the form and code is secure against copying?

Question

I have an Excel file that has a form and macros. I will give this Excel file to users. However, the form and the code must be protected against copying. I thought to break the Excel macros into DLL so that the VBA code can not be recovered.

Would you know if from the DLL we can recover the original VBA code?

Do you have other ideas to protect against copying?

Thanks

score 2 · Answer 1 · answered Jul 19 '18 at 16:32

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You can add a password to a VBA project ... http://www.ozgrid.com/VBA/protect-vba-code.htm

To protect your code, open the Excel Workbook and go to Tools>Macro>Visual Basic Editor (Alt+F11). Now, from within the VBE go to Tools>VBAProject Properties and then click the Protection page tab and then check "Lock project from viewing" and then enter your password and again to confirm it.

answered Jul 19 '18 at 16:32

3-14159265358979323846264

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Note that no matter what you do, a determined and talented attacker will be able to recover your code! – 3-14159265358979323846264 Jul 19 '18 at 16:35
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They don't even have to be that now-a-days – QHarr Jul 19 '18 at 16:37
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How about, anyone with access to Google, then!! – 3-14159265358979323846264 Jul 19 '18 at 16:38
lol :-) Pretty much – QHarr Jul 19 '18 at 16:39
And to unlock that code without the password, simply follow the steps here: https://stackoverflow.com/a/27508116/2507160 – jeffreyweir Jul 19 '18 at 16:43
@jeffreyweir That looks like really hard work - I have a way that only uses standard issue programs on my mac and not any "special password" software... – Solar Mike Jul 19 '18 at 16:56
@SolarMike No hard work...just cut and paste. Note that it's designed to crack VBA passwords (which are a bit more secure) and not workbook protection (which can oftentimes be done with a HEX editor or other methods). I have this code in my utilities add-in, so it's no bother to push ALT F11 and fire it off in need. – jeffreyweir Jul 19 '18 at 16:59
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Not even a Hex editor... simpler than that - just open in another package... and poof password gone... – Solar Mike Jul 19 '18 at 17:01

score 1 · Accepted Answer · answered Jul 19 '18 at 19:32

As you might find out soon enough, many people will suggest that you simply don't build applications in Excel that need to be secure, however, I have outlined a few things you can do in order to help protect your code.

You might consider using a combination of these items in order to best protect the code. Always make a backup of your code before doing these things, or else you risk losing it permanently!

Password Protect the VBA Project (as has been mentioned.)
Add code obfuscation (I've used this link before. You need to test your code after using it though. It basically runs a find-Replace on variables you enter)
Use a protection program such as Unviewable+ (Might be a little pricey, and I admit I've been able to still access code locked with that program)
Use another method to make your VBA project "Unviewable" (I've used This Method and even wrote my own code to implement that method automatically)
Do as you suggest and compile VB code into DLLs which are called from your Excel file (This should "hide" your code from users, but it also requires them to have multiple files in order to use your spreadsheet)
You could additionally password protect the entire workbook. This encrypts the VBA code inside your file. (However, the users to which you give the password can easily remove that password thus storing the code plainly again.) [Edit: This one you would want to combine with item 1 or 3 so that user's can open the file and use it but still cannot access the code]

I used a tool called VBASH (www.ayedeal.com/vbash), it seems to be a combination of #2 and #3. It obfuscates the macro and make vba project unviewable. — YeP, Mar 06 '19 at 18:05

how to secure an excel file so that the form and code is secure against copying?

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