how to prevent your Cydia tweaks from getting cracked?

Question

I'm working on a new Cydia tweak, It'll be paid! The problem that I don't want it to be cracked/pirated/redistributed. Are there any scripts I can use in my tweak?

Few examples:

1. A script that will mail you a log securely to know if the user bought it or he got it cracked.

2. A script that will check your payment in a database, if it's exist then the tweak will be activated on the device, if not then the tweak will be disabled.

3. A script with UIAlertView that checks if you bought the package from Cydia Store it will activate the tweak, otherwise it'll open a pop up with UIAlertView to tell you that "You got this package with an illegal way, Blah Blah Blah.." and then when you click the "OK" button it'll take you to safe mode till you uninstall the tweak or till you buy it from safe mode. (Most important one)

Answer 1

You can't really protect software from being cracked. It is always a race between stronger and stronger DRM (and usually more annoying to legit users) and the crackers to see the challenge and do cracking for fun (or fame, or both).

What I would suggest, instead of investing large amount of time in coming up with DRM schemes and then implementing and testing, rather invest that time in the functionality of your product and testing it more thoroughly. If your product is good and priced right, people will buy it. Sure, some will pirate it, that is inevitable, but you will get rewarded for your work.

Answer 2

You could put an MD5 or an SHA1 check within your tweak in various locations in your functions just to make sure that if they modify your tweak it wont match. Also instead of packaging your tweak in a deb file you could get it remotely download after verification of some sort.

EX:

Example.tweak

-/var/root/downloadscript (can be any path) (this can also be used so that they cant just extract the file in question and install it)

-DEBIAN/control (config file for deb)

-PostInstall (Post deb installation script) https://wiki.ubuntu.com/PackagingGuide/Basic#postinst_and_prerm

Download Example.tweak from cydia

Using the 'postinst' execute the /var/root/downloadscript you can use /usr/bin/deviceinfo -s which will print out serial number and use $POST to your server to send the said serial number and download some kind of licence, inside the licence you can include maybe UDID, mac address some other checks that would be checked out by your tweak.