Category Archives: Apps

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Authenticating Saved Data in Apps

Cheating is becoming a bigger and bigger problem for developers. You only have to look at the leader boards for the ‘Flappy Bird’ game and you will find hundreds of users on 999999. It’s near impossible to actually achieve that in the game, but users can easily access the files used to save this data and modify it to meet their needs.

It’s not only high scores that are an issue. Developers need a way of keeping track of in-app purchases, and this is often saved on the device in the form of JSON or SQL files. This obviously opens the door up to users activating features or items without paying for them.

There is however, a simple solution to check if the data being saved, then loaded back into the app is genuine or not. This is in the form of a checksum. A simple calculation using the data you want to save, a random key, and the resultant. Simply calculate a checksum at data save and store the result with the saved data. When it comes to load the data back in, perform the same calculation and ensure that the result matches the result that was saved.

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