'this workbook will self destruct!'

[beccy]

i am sending a price guide in excel format to customers and I would not like them to reuse or copy the data...

is there a way of setting something that will prevent people copying it and delete the contents of the sheet after a certain period of time?

any thoughts would be appreciated!

 

[Legacy 1363]

cfree36

Have a look at my earlier post.

After a user opens the WB with macros enabled, all that needs to be done to avoid what you posted is :-

- copy the data to another workbook, or
- set EnableEvents to False so that the Event Procedures do not work

 

[cfree36]

C.O. Jones

My reply was merely a way to force the user to enable macros.
In order to achieve the desired results many of these suggestions would have to be utilized.
In any case Excel is NOT a secure environment, and none of these suggestions would be fool proof for an experienced user.

It's like putting security tags on garments at the store. They keep most people from stealing... but the experienced thief will still get out with the clothing.
That's not to say however that the security tags don't prevent most theft.

 

[fireslguk]

The easiest way to keep them from copying the data is to protect the sheet with a password. If you protect a document in Excel 2003, it gives you an option of things people can and cannot do. Simply clear the check boxes saying 'Select Locked Cells' and 'Select Unlocked Cells'.

Then no one will be able to copy the contents of the sheet to their clipboard without cracking the password (which is unfortunately very easy to do).

A really cheap, lazy, and possibly less than sufficient way to make it "self destruct" would be to apply conditional formating to each cell.

Select all the cells you want to 'destroy' and apply a conditional format, with a formula that says something like:

= today() > mm/dd/yy

The date of course being the last date you want the file to be readable.

Then set the format to something that makes the data unreadable (black background or white text... change the font to wingdings... whatever... get creative).

You could use the same idea, combined with an if statement and in each cell, change the current value to:

= if ( today()>mm/dd/yy , " " , Normal Value for cell )


Neither of these methods is very sophisticated and they don't completely destroy the data. It probably wouldn't be very difficult to destroy the data using a macro of some sort, but then you would have to find a way to prevent people from opening the file if they disable the macros.

You might want to look into using a more secure document, such as a pdf if you really don't want them to copy the data, but then it's going to be a lot harder to make it self destruct.

Then no one will be able to copy the contents of the sheet to their clipboard without cracking the password (which is unfortunately very easy to do).


by how means ?

 

[MTBer]

You won't secure excel, if it is so important that people cannot copy data etc, I suggest you look at VB6 Front loader applications to manage your excel workbook, this will manage the password to open, set it to something like 15 digit alpha numeric mixed case, and will automatically enable the macros, you can then test the expiration date of the workbook, and allow it to be open or not. You could also run the instance of excel in the background.

You can't stop copying the data from the workbook, you may disable the cut/copy/paste commands, but I would just link to your workbook and then value the links. Not difficult.

If you really want to stop people accessing the data after a certain date, maybe start looking creating functions to read/write registry keys upon file opening. Combine this with a front loader, and you will be getting about as secure as you can, but an experienced user will break in if he wants.

Paul

 

[uveenhacked]

print screen... would be another problem