Thanks for the info! Especially the bit about the re-trial is interesting. But i have one question: You use the IMEI number. What if the user gets a new phone? Aren't app downloads tied to a user's Google Checkout account. If the user gets a new phone, uses the same Google Checkout account, he/she has to buy your app again. Shouldn't you use the 'ANDROID_ID' instead?
On Feb 26, 8:02 am, String <sterling.ud...@googlemail.com> wrote: > On Feb 25, 7:58 pm, Streets Of Boston <flyingdutc...@gmail.com> wrote: > > > How do you make a time limited trial version, where limiting the time > > is fairly fool-proof? How do you know how long the user has your app > > installed (including the possibility that the app has been uninstalled > > one or more times...)? > > I go the server-registration route. The app in question already needs > net access, and I have a server that it talks to already, so I just > created a narrow MySQL table server-side and a simple PHP script to > interface with it. Essentially, I store the IMEI, app version number, > and the date of first use, and use that to validate the trial period. > My original implementation didn't include version number, but I soon > realized that it was desirable to let people re-trial when I released > a new version. > > I've also decided not to bother with any encryption on the trial > period validation. I recognize that my approach is vulnerable to MITM > attacks, but it's sufficient to keep honest people honest; if > someone's going to that much trouble to screw me out of $2, there's > not much hope, is there? Besides, the whole Android-market piracy > aspect is a much bigger security hole. It's far more likely that > someone will simply download my license app from a warez site than > bother with cracking my validation routine. > > String -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
