Time Blocking
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I researched a bunch and settled on Visual Protect. It's certainly not perfect, but it seems to work so far. And it's easy to use -- no additional code necessary. Regards, Nick Hodapp / CoDeveloper
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There are lots and lots of ways to do this, and every single one can be broken by crackers (why would one want to bust a $20 product is beyond me... ). In any case, setting this up is pretty trivial. Stick a registry key in your profile that indicates the time when the product was first ran - GetSystemTime is good enough for this. Then check aganst this stored-off value and if the different is greater than your limit, stop the product. Also check for it going less than the start to see if someone has diddled with the clock. Extensions and variations: keep a running tally of the total number of time used by the program and shut off after that time. Or use it to validate the above value. Watch for people setting the clock while the program is running - les than 90 minutes is probably ok, but more than that (esp a full 24 hours) is probably cheating. Check and make sure that when you write the registry key that the value is still there; under NT you can prevent a key from being modified, so this can trap for that. Again, none of this will prevent a determined cracker, or even a half-good one.
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Another Idea, For an Internet Downloaded App Preset an expiry date in your program, Now rebuild your program for the next date day +1 Every day upload a new program for the ftp er, Also if you have an internet type application have it check the time over the net as well as the local time. Be wary of Timezones also screwing up the system. But as Todd say's in another post, Crackers will be able to Crack it, Regardz Colin Davies
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There are lots and lots of ways to do this, and every single one can be broken by crackers (why would one want to bust a $20 product is beyond me... ). In any case, setting this up is pretty trivial. Stick a registry key in your profile that indicates the time when the product was first ran - GetSystemTime is good enough for this. Then check aganst this stored-off value and if the different is greater than your limit, stop the product. Also check for it going less than the start to see if someone has diddled with the clock. Extensions and variations: keep a running tally of the total number of time used by the program and shut off after that time. Or use it to validate the above value. Watch for people setting the clock while the program is running - les than 90 minutes is probably ok, but more than that (esp a full 24 hours) is probably cheating. Check and make sure that when you write the registry key that the value is still there; under NT you can prevent a key from being modified, so this can trap for that. Again, none of this will prevent a determined cracker, or even a half-good one.
>> Again, none of this will prevent a determined cracker, or even a half-good one. Agreed, but what you suggest is cracked in 10 minutes, using RegSnap, RegMon and Regedit. (We use a third party copy protection scheme, which I eh... tested). It uses encrypted keys which also contain some of the information about the type of the license (time/user limited - trial or full version, etc...). Althoug I did not remove the key's encryption protection, I was always able to fool the program in extending (renewing) the evaluation time/license. I do not have an adequate answer to this problem, but maybe it is still worthwile to invest in a good third party protection program (And try to break the security yourself when you are evaluating the product so you have an idea how difficult it is for a thief to rob you from your bread and butter)