Re: Foolproof Protection of VBA codes
I've seen Roy's approach before - or at least I think I have, it uses the in built mechanisms of Excel with regards to viewing projects in a shared workbook. Excel thinks the project is shared - even though the workbook isn't so won't show you the code. It's pretty ingenious, but imo even easier to view than the usual password protection. I haven't tried googling it, but I think it's a little less well known than the password cracking/hex approaches so users are less likely to find how to view the code (although in fact the method is easier than usual password protection).
Ultimately there is no sure-fire way to protect your code, Excel is inherently insecure. I believe you'd get security by writing the code in .Net, compiling it and using it as an add-in. It is however much more work, so it's always a balance of how usable the code is or easy to write vs how bothered you are about people viewing your code. IME, for a commercial package, users are far more bothered about having support than they are about having a few free copies so are happy to pay for things.
If you're really bothered, the package that seems most secure to me (though I haven't tried it) is LockXLS since it wraps the workbook in an application. Though to be honest, I'd just stick a password on it/use Roy's method and be happy that >95% of people will use it properly.