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A.D. Tejpal View Drop Down
Microsoft MVP
Microsoft MVP

Joined: 30 Jun 2008
Status: Offline
Points: 192
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    Posted: 08 Jul 2008 at 10:36pm

Explanatory Notes:    

     This sample db is meant to secure Licensee particulars (Or date of expiry for 
free trial) in a tamper-proof manner. Often, such information is stored using registry 
settings and/or hidden tables. With sufficient skill and motivation, contents of 
registry or hidden/system  tables can be tampered with. 

     For utmost security, the sample db demonstrates storage of such information in hard 
coded form directly in the code module of an auxiliary Mde file called LockFile.mde.
(As far as known, it is not possible to get into the code module of an Mde file). 
Creation of this lock file is automated for versions up to Access 2003 (See note below).

     To start with, the main application file (say MainFile.mde) is shipped to the client 
along with LockFile.mde (having hard coded information for expiry date of free trial).
This lock file is very small in size and does not have any tables or queries. 
Whenever the main file is opened, it grabs necessary information from the lock file 
(placed in the same folder as the main file) and can function normally only  if expiry 
date for trial is not yet over. 

     As & when the client becomes eligible, new lock file containing his Licensee status 
can be sent to him. Now the main file will be able to work smoothly (without any limit 
to expiry date), displaying the name of licensee prominently.

     LockFileMaker.mdb is used for automated generation of lock files. Step by step 
guidelines are given in the accompanying file LicenseLock_ReadMe.htm
     For Access versions up to 2003, programmatic conversion from .mdb to .mde 
format is found feasible via SysCmd argument 603. It is an undocumented argument and 
is no longer found effective in Access 2007 onwards. For these later versions, manual 
conversion to .accde format can be done.
     The package contains separate versions for Access_XP and Access_2K.
Since creation of Mde files is involved, it is important that Access_2K version is not
attempted to be used on Access_XP installation (Access_XP can handle Mde conversion
only if the mdb file is already in XP format i.e. Access 2002). Of course, the finished product
(LockFile.mde and MainFile.mde) generated by 2K version of this package, can be used
on XP installation as well.
Versions - Access XP & 2K

References - OLE Automation, MS Scripting RunTime

Download File >>: uploads/37/

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