making a 30 days validation program.. [Archive]

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noam309

Sep 29th, 2006, 09:42 AM

Hi,

I have some applications that I made , and a lot with your great help .
I want with form load it will show an registration form that the user has to enter the : name and serial number , and the program will count 30 days and then will stop working.. does anyone know ,and can help me with it?

Villy

Sep 30th, 2006, 03:41 AM

you can just use hte regestry om the device to save the date when the program fist was in use. And then chek the date on the PDA every time the program starts against the date you saved. One problem with this teknik is that the user can just cande the date om the PDA on the PDA and the Pragram wil work again.

PS:
sorry my bad english

ravininave

Oct 29th, 2006, 04:12 PM

Instead of 30 days you can keep 30 or 40 uses which is very safe. Initialize it from Registry.

vbud

Nov 3rd, 2006, 12:55 AM

Though Registry is commonly used for this I would suggest that you choose stronger options along with this. When using the registry Use API to save at registry locations that has meaningless names and encrypt the values. Basically the values that you need to save is the First Run Date and the Last run date. Then from this you need to calculate how many days have elapsed and if its above 30 then end the application. Bear in mind though that users can easily backdate their system time and try to fool the trial period calculation. Knowing this, what you need to do is at each run, check to see if the last run date that you saved is greater than the current date, if so then you know that the system date has been tampered with and you can exit the app.

Also you may want to generate a file somewhere under windows directory and save the same information in encrypted format on the user's PC. This way you have 2 places where you can verify the dates. Also if you want to go to a further extent, you can implement a CRC check on the EXE each time it is run and compare it against a CRC that you have saved in a file or registry, this way you are making sure that the trial version of you software has not been tampered with. Hope this helps.