Excel Security

Z

Zygan

Hello i have written a program that defines and works out very lengthy
formulas. I am trying to sell the program for what i believe to be
enough money to protect. what i need is to be able to burn it on to a
cd the put a time limit on the cd hence the user cannot use it after
say 30 days or 5 uses. this would not be drama if i could save the
file. e.g just use a counter that is VBA protected. But because it is
on a cd it cannot save. i tried an idea of using the current time and
date to be checked when excel started and that gave me a protection in
which i was satisfied with. however once the 30 days up cd is unusable
i could put a password on it to override the time checker however my
buyer would have to enter the password every time for use. So basically
what i need/want is a program excel/not excel that will limit the usage
on the cd and that is full changeable and overidden i was thinking that
once the workbook was purchased that the password i give them would then
delete a line of code enabling them to save the workbook as it is save
protected ? can anyone help ?
 
J

Jim Rech

Any security device you come up with can be easily defeated but you could
write a entry to the registry when the password is first entered and then
check for it before presenting the password dialog again.

--
Jim
message |
| Hello i have written a program that defines and works out very lengthy
| formulas. I am trying to sell the program for what i believe to be
| enough money to protect. what i need is to be able to burn it on to a
| cd the put a time limit on the cd hence the user cannot use it after
| say 30 days or 5 uses. this would not be drama if i could save the
| file. e.g just use a counter that is VBA protected. But because it is
| on a cd it cannot save. i tried an idea of using the current time and
| date to be checked when excel started and that gave me a protection in
| which i was satisfied with. however once the 30 days up cd is unusable
| i could put a password on it to override the time checker however my
| buyer would have to enter the password every time for use. So basically
| what i need/want is a program excel/not excel that will limit the usage
| on the cd and that is full changeable and overidden i was thinking that
| once the workbook was purchased that the password i give them would then
| delete a line of code enabling them to save the workbook as it is save
| protected ? can anyone help ?
|
|
| --
| Zygan
| ------------------------------------------------------------------------
| Zygan's Profile:
http://www.excelforum.com/member.php?action=getinfo&userid=34423
| View this thread: http://www.excelforum.com/showthread.php?threadid=547081
|
 
R

R. Choate

The other folks put it mildly. You cannot create an Excel-based application that you can sell and protect from duplication and
elimination of all security and almost all of the profits you seek. You may in fact find your new app everywhere on the internet
with users laughing at your attempt to hide it. If you want more advice on this, you might write to John Walkenbach (j-walk.com) and
ask him how he avoids getting ripped off with his Excel add-in. He may tell you that his program is cheap enough and his reputation
is solid enough that people generally don't want to rip him off and also don't feel the cost of a hacking program is worth the
savings. The PUP add-in he sells is an Excel tool, not a stand-alone program. He allows a free trial version and after that I think
he uses nag pop-ups to register rather than a self-destruct routine. I'm sure he will offer good advice, but in the end, you can't
lock down an Excel-based app....yet. The new Excel due out in a few months might offer much stronger security than the old one.
That would give you more of a fighting chance. In any case, prepare to not charge much for your application or it will get hacked
and used for free, that is your no money back guarantee. There are so many people out there who spend all their time working on
hacking programs that you just can't stay ahead of them; just ask Microsoft.
--
RMC,CPA



Hello i have written a program that defines and works out very lengthy
formulas. I am trying to sell the program for what i believe to be
enough money to protect. what i need is to be able to burn it on to a
cd the put a time limit on the cd hence the user cannot use it after
say 30 days or 5 uses. this would not be drama if i could save the
file. e.g just use a counter that is VBA protected. But because it is
on a cd it cannot save. i tried an idea of using the current time and
date to be checked when excel started and that gave me a protection in
which i was satisfied with. however once the 30 days up cd is unusable
i could put a password on it to override the time checker however my
buyer would have to enter the password every time for use. So basically
what i need/want is a program excel/not excel that will limit the usage
on the cd and that is full changeable and overidden i was thinking that
once the workbook was purchased that the password i give them would then
delete a line of code enabling them to save the workbook as it is save
protected ? can anyone help ?
 
R

R. Choate

John can probably help at least to a limited extent. It does involve laws in different countries but he should still have something
worthwhile to say. Also, We tend to sometimes over-emphasize the lack of Excel security in newsgroups because so many people believe
Excel has decent security when it doesn't have good security at all. Additionally, once the cat is out of the bag it is very, very
hard to prove how it got out or that somebody did it with malicious intent.

Good luck with your project.
--
RMC,CPA



thanks for the advice i dont really care if someone hacks it because its
such a large program that i would only give it to potential buyers and
the program is copyright to me. Plus to access a trial they have to
sign an agreement written by my solictor to not distrubute the software
or reproduce. However my solictor says that i cannot put a time limit on
the agreement with my potential buyer as my program does not have a time
limit therefore once they sign to a trial its there for ever as a trial.
However me solictor says that if the program informs them of "trial"
period and they hack it they have breached copyright laws. So forgive
my rudeness but the question i pose is. hackable or not (nothing is
ever safe) I need a time limit or a non-excel program to put a time
limit on the workbook even if it is not 100% proof. It just simply
needs to work. I will check out John Walkenbach thanks for the advice.
 
C

CLR

Have you considered just a Workbook_Open macro that would compare the current
date to a key date and if enabled, would erase all the good-stuff?

Vaya con Dios,
Chuck, CABGx3
 
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