Need help to build a solid security system for a workbook

[garmont]

I am developing an application that i want to keep as secure as possible from piracy. I've built in user id and password. i utilize macros wherever possible, but have relied on a couple of workbook events to handle a lot of the security features. i just found a couple of ways to defeat these events and open the workbook to saves without locking away all the good stuff....
does anyone know how to really lock up a workbook and keep it from being copied when sheets are supposed to get hidden upon closing, along with other security features like time checks, id's, and lockout 'flags'???
thanks,
garmont

 

[shajueasow]

Hi,
Welcome to the board.
Not to dishearten you, but a general warning.... Don't try to build a security system for an EXCEL workbook. There are many ways to bypass many of its settings.
The macros can be disabled. The password protection of sheets and workbook even can be destroyed. And once you are going to hand over this thing out, then you cannot say what all things might happen to your workbook.
But this all depend upon the excel knowledge of the end user.
And more over if any of those to whom you hand over your wokbook is a visitor to this site.........then think of that too.
But anyway, best wishes for your effort.

 

[garmont]

Hi shajueasow,
Thanks for your comments. And I am somewhat disheartened, but not your fault....
I'm not ready to give up yet, but if passwords can be destroyed - well, that gets me closer to giving up. How hard is it to get past the workbook protection password?
Can the password protection for VBE be destroyed also?
My thinking now is to make all functionality (of the valuable intellectual property) run thru macros, so pausing or breaking VBE won't allow the program to work.....

I agree that the average user won't know how to get around these features, but if someone sends their copy to a hacker/excel wiz, then all is lost?

garmont

 

[shajueasow]

The password given to protect a sheet or workbook is stored by excel as a "number"...is it just a number ....I am quite not sure. So as you know, there are many ways to reach a number. Like 12 is 10+2, 11+1, 9+3,8+4 etc, etc. And some of these password breakers, just get that number and makes a pseudo string of letters that matches to the number and uses it to open the protection.
Password protection for VBE can also removed or replaced....
When things like these are seen on boards, a very useful tip that I read is that try to make an addin, and then protect it. It can also be tampered with. It all depends how important your functions are to others. Try using some other platforms than EXCEL if possible,...for EXCEL is "known" for its lack of security.

 

[garmont]

Got it. Thanks. After reading the forum's note on password breaking, i was hoping my request didn't come across as asking for a "how to" but just a relative difficulty idea. Since then I found the password "retrieval" = breaker "services" available all over the place, so, now I am totally disheartened .
At least I am better educated on where I stand re losing control of my IP.
I'm going to learn a lot more about addins, so I may be back asking similar protection questions or abandon Excel for this purpose.

 

[pfarmer]

Got it. Thanks. After reading the forum's note on password breaking, i was hoping my request didn't come across as asking for a "how to" but just a relative difficulty idea. Since then I found the password "retrieval" = breaker "services" available all over the place, so, now I am totally disheartened .
At least I am better educated on where I stand re losing control of my IP.
I'm going to learn a lot more about addins, so I may be back asking similar protection questions or abandon Excel for this purpose.

One method is to consider using references to secure external procedures. Where truly necessary you store the data off the book and reload it on startup. Various routines can exist off the workbook and can be called by the workbook.

Without knowing your particular needs it is hard to say exactly how you should proceed. Regardless of how secure you think you can make something there is almost always someone out there that can prove you are not regardless of the applications.

Perry

 

[Legacy 98055]

The easiest and cheapest way I have found to "secure" a workbook is to embed it as a resource file into an exe or dll using VB. If this is an option for you, you may wish to look into it. With a bit of extra code that is freely available off the net, you can even encrypt the file.

 

[erik.van.geit]

The easiest and cheapest way I have found to "secure" a workbook is to embed it as a resource file into an exe or dll using VB. If this is an option for you, you may wish to look into it. With a bit of extra code that is freely available off the net, you can even encrypt the file.

Hi, Tom,
can you provide some intresting links about this ?

kind regards,
Erik

 

[Legacy 98055]

None that I know of Eric that are spefic to Excel workbooks. In VB, you can create resource ID's. It's mainly for storing icons, bitmaps, ect... However, though it's a pain with large files because you are limited to 64K per ID, you can store pretty much any custom resource as a byte array. You can control your workbook from the exe. But, as with any attempt to secure a workbook, it's not full proof. However, it's a lot more "secure" than anything you can do in hosted VBA.

 

[erik.van.geit]

hmm, stuff for next decade
thank you!!