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David Guest
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Posted: Wed Mar 01, 2006 10:11 am Post subject: Time trial - can the user alter system clock? |
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Just a quick question. When setting up a trial version of my application to run out after a set number of days, is this method protected against a user altering the system clock to extend the trial version? If so, how is this conceptually implemented into the applications code (i.e. is the system clock simply recorded at the time of install to be checked against later?).
Best wishes,
David |
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Infralution
Joined: 28 Feb 2005 Posts: 5027
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Posted: Wed Mar 01, 2006 9:51 pm Post subject: |
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Yes there is protection against clock winding. Typically customers do one of two things to attempt to extend evaluations.
1. Set their clock forward way into the future when they first install and run the machine - then set the clock back to the real date. Hoping that the software will simply compare the current date to some expiry date.
2. When they hit the expiry date then set the clock back before they use your application.
The EvaluationMonitor class protects against both of these by recording the last date/time that the software was run. It will then detect any significant winding of the clock backwards and set the Invalid flag. It is up to you to decide what you want to do if this flag is set. _________________ Infralution Support |
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