AnsweredAssumed Answered

vrf Maximising Vee window

Question asked by VRFuser on Feb 19, 2008
Hi Simon

 

I don’t have a code example to hand but we have done something like this previously based on the windows system time.

 

The key we found was to not only check for the time period elapsing but also to keep a log of the system time to detect any potential tampering.   You can do this by periodically storing the system clock in a hidden log file and checking for inconsistencies such as current date time earlier than license start time, current date time earlier than previous usage, etc.

 

This log could be stored as a text file somewhere on c:.   We always found it best to put something like this either in the registry or as  file in the c:windows folder (or c:windowssystem) etc in order to discourage user deletion or editing.  If it is a file, you can give it an unrelated name and you can also easily scramble the contents by passing the text through a simple formula in vee.   Of course if the file goes missing that could be detected as tampering too.

 

I am sure this is not bomb proof but is probably adequate to protect against most user tampering.

 

Cheers

 

Nick

 

 

  _____  

From: Simon Parfitt [mailto:parfitt@IceraSemi.com]
Sent: 19 February 2008 15:27
To: VRF
Subject: [vrf] Time expire code

 

Hi All

 

I am trying to find of a simple but secure way of placing a time limit on some VEE use. Something like a time expire licence. I have thought of just reading the system clock but that’s easy to wind back. Of writing some date/time to a file someplace on the c drive. But I am sure someone could find that. I did think of reading some internet clock but then they need to be connected to the internet.

 

Has anyone come up with nice way in the past?

 

Simon

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