How to make an Excell-sheet un-usable!
 

Hi,


I've made an Excel program and would like to have that after a certain date
is becomes totally un-usable for the users. I thaught of putting in te open
workbook for example a check with that specific date and close the workbook.
But if you do not enable the macros, it will be possible to get into the
code and remove this code.

Is there another and for sure better way to do this. Like erasing part of
the code, and that it cannot be traced easily?


thanks a lot in advance,

Yves

How to make an Excell-sheet un-usable!
 

Yves,

The only way to accomplish this is to make the workbook unusable
if macros are not enabled. To do this, you would hide necessary
worksheets with the save event. If macros aren't enabled those
sheets won't unhide and the workbook is useless without them.
If macros are enabled, the Workbook_Open code would unhide
them.

Please note that Excel is not in any way secure. Passwords for
worksheets and VBA project code can be cracked easily by
an experienced user.

There's a pretty good thread with lots of code, ideas, etc. he
http://makeashorterlink.com/?R48812F64
It'll also point out some of the insecurities of attempting this.

John



Yves Janssens wrote:

Hi,

I've made an Excel program and would like to have that after a certain date
is becomes totally un-usable for the users. I thaught of putting in te open
workbook for example a check with that specific date and close the workbook.
But if you do not enable the macros, it will be possible to get into the
code and remove this code.

Is there another and for sure better way to do this. Like erasing part of
the code, and that it cannot be traced easily?

thanks a lot in advance,

Yves

How to make an Excell-sheet un-usable!
 

Thanks a lot John for the good information


Yves


"John Wilson" wrote in message
...
Yves,

The only way to accomplish this is to make the workbook unusable
if macros are not enabled. To do this, you would hide necessary
worksheets with the save event. If macros aren't enabled those
sheets won't unhide and the workbook is useless without them.
If macros are enabled, the Workbook_Open code would unhide
them.

Please note that Excel is not in any way secure. Passwords for
worksheets and VBA project code can be cracked easily by
an experienced user.

There's a pretty good thread with lots of code, ideas, etc. he
http://makeashorterlink.com/?R48812F64
It'll also point out some of the insecurities of attempting this.

John



Yves Janssens wrote:

Hi,

I've made an Excel program and would like to have that after a certain
date
is becomes totally un-usable for the users. I thaught of putting in te
open
workbook for example a check with that specific date and close the
workbook.
But if you do not enable the macros, it will be possible to get into the
code and remove this code.

Is there another and for sure better way to do this. Like erasing part
of
the code, and that it cannot be traced easily?

thanks a lot in advance,

Yves

How to make an Excell-sheet un-usable!
 

Assuming your spreadsheet will be password protected with all cells
hidden......I always insert a column on the left, insert the formula
'=today()' then identify a cell which drives much of the information
and add the fomula =if('the cell with =today() in it''the date in
numbers you want the sheet to stop working',"")

i.e. if today's date is greater than the preset date for the sheet to
cease functioning then return blank data in the cell in which the
formula appears.



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