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HomeForumGeneral DiscussionHacking the save file

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March 22, 2011 at 10:22 pm #411

CyberGreg

I’m trying to confirm that the binary file format used in our saved games will prevent a casual hacker from changing any of its values. If you build and run in the simulator you can locate the savefile.sav and drop it onto the Property List Editor and view its contents.

What I’ve found is that all I have to do is just save the file, without making any changes to the data and it makes the file not usable. Even though it still looks and opens up in plist editor just fine.

Without going into the whole “cracking / hacking” discussion (we all know that nothing is uncrackable, pretty much anything is editable via a hex editor), if we can’t easily alter the values saved in this file then I can use this for my Game Center data.

Just wondering if anyone has any information about binary files from NSArchiver.

Here’s the top line of unsaved data:
bplist00‘;<T$topX$objectsX$versionY$archiver—TrootÄ'(.5U$null?

Here’s the top line of the saved data:
bplist00‘./X$versionX$objectsY$archiverT$top#)U$null›

Edit: okay that was fun, seems some of the code actually “did” something and wouldn’t show up in the post… Nat – if I broke the interweb, I’m sorry :-)

March 23, 2011 at 3:38 am #1661

Nathanael Weiss

Hmm.. Wish I had some info on this.. Maybe try Googling “how to hack iphone games” for more insight.

March 23, 2011 at 8:06 am #1664

cosimus

maybe you should use a hexeditor instead of the plist editor

March 23, 2011 at 12:10 pm #1666

CyberGreg

Tracking the discussions on a few forums including the Apple Dev ones, each time someone talked about hacked scores it ended up they were saving score data to NSUsDefaults. NSUsDefaults are easily edited with a plist editor on a jail broken device. So when I saw that I could open and read the .sav file I naturally assumed I could edit and save. So far I cannot.

Regarding a hex editor; my goal is to prevent the casual hacker, who would give up after the first few tries where any change they make and the game reverts back to the starting defaults.

I’ll keep looking, but not too much more. I think I’ll try to use NSArchiving.