Non OS dependednt date\time

[GMMorris]

Hi,

 

I'm writing a piece of software for licanse managment, and I have reached a "wall" many other before me have:

 

Even if I make the serial number date dependent (the key is invalid after a specific date) the user can always change the date in the OS to trick the installation software.

 

So I was wondering- is there a way to determine the date without the OS? I'm assuming there isn't, so I was wodering- does the processor have some kind of "Timer" or something that the user can't access but changes to count the time, so I can compare the time which has passed between two points in time?

 

Meaning, a counter of some sort which isn't OS dependent but can help me determine what the length of time between the time of the software's installation and Now() is?

 

Thanks, any other ideas of how cI can secure keys would be helpful.

[PlausiblyDamp]

You could always save the current date and time and the installation date and time in an encrypted format somewhere, when the application starts compare the current time to the install time and refuse to work if it has expired. If it hasn't expired then compare the current time with the time of the last application exit - if it is now earlier in time then there is the possibility of tampering with the system clock.

You may need to be careful in regards to things like differing clocks for summer / winter in some countries or the possibilty of time syncronisation in a network environment though.