I want to post here a question that I have [posted on IT Security](https://security.stackexchange.com/questions/38703/using-apple-nskeyedarchiver-class-without-encryption-to-save-score-data-locally) but without answers :(

I have a question about the security of NSKeyedArchiver, [a subclass of NSCoder of Apple Foundation.framework](https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSKeyedArchiver_Class/Reference/Reference.html)

In my Apps, for management of the Apple Leaderboard I used [ABGameKitHelper by Alexander Blunck](https://github.com/ablfx/ABGameKitHelper). I have notice that this helper uses AES encryption to save scores in local when the Apple Leaderboard is not accessible (for example there's no network, etc) with the NSKeyedArchiver class.

So, my question: is there a real possibility that an attacker can decode the data written without encryption using NSKeyedArchiver, and understand the key-value pairs? And also modify the score data, reconnect to the network and waiting for automatic Leaderboard update from ABGameKitHelper? Or is useless to encrypt data?

Thanks in advance, Alesanco