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iosobjective-cencryptionplist

Encrypting Plist File Method

I have a Property List titled GameData.plist. I am trying to see if the way that I am encrypting the plist is correct or not. Since you are unable to manually edit the main bundle files (which would have been an easy way to see if the data was indeed encrypted now), and I don't seem to be finding my plist in the available data through iExplorer, I am not sure if anything is actually being encrypted.

The goal is for the information to be overwritten with encrypted data. Im not sure if that's how it works, I am just trying to prevent the data in the plist to be viewed outside the app running or not running. Here is what I am doing:

- (void)encryptionWithAES256 {
        .
        .
        .
    NSString *path = [[ NSBundle mainBundle] bundlePath];
    NSString *finalPath = [ path stringByAppendingPathComponent:@"GameData"];
    NSDictionary *plistDic = [NSDictionary dictionaryWithContentsOfFile:finalPath];
    NSLog(@"Plist: %@", plistDic);
    
    NSData *plistData = [NSKeyedArchiver archivedDataWithRootObject:plistDic];
    NSData *encryptedData = [plistData AES256EncryptWithKey:@"<ENCRYPTION_KEY>"];
    [encryptedData writeToFile:finalPath atomically:YES];
        .
        .
        .
}

NOTE: for testing purposes, the GameData.plist is simply the default plist that Xcode creates for a project, as shown below:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
    <dict>
        <key>Test</key>
        <string>GameDataTest</string>
        <key>CFBundleDevelopmentRegion</key>
        <string>en</string>
        <key>CFBundleExecutable</key>
        <string>$(EXECUTABLE_NAME)</string>
        <key>CFBundleIdentifier</key>
        <string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
        <key>CFBundleInfoDictionaryVersion</key>
        <string>6.0</string>
        <key>CFBundleName</key>
        <string>$(PRODUCT_NAME)</string>
        <key>CFBundlePackageType</key>
        <string>APPL</string>
        <key>CFBundleShortVersionString</key>
        <string>1.0</string>
        <key>CFBundleSignature</key>
        <string>????</string>
        <key>CFBundleVersion</key>
        <string>1</string>
        <key>LSRequiresIPhoneOS</key>
        <true/>
        <key>UILaunchStoryboardName</key>
        <string>LaunchScreen</string>
        <key>UIMainStoryboardFile</key>
        <string>Main</string>
        <key>UIRequiredDeviceCapabilities</key>
        <array>
            <string>armv7</string>
        </array>
        <key>UISupportedInterfaceOrientations</key>
        <array>
            <string>UIInterfaceOrientationPortrait</string>
            <string>UIInterfaceOrientationLandscapeLeft</string>
            <string>UIInterfaceOrientationLandscapeRight</string>
        </array>
        <key>UISupportedInterfaceOrientations~ipad</key>
        <array>
            <string>UIInterfaceOrientationPortrait</string>
            <string>UIInterfaceOrientationPortraitUpsideDown</string>
            <string>UIInterfaceOrientationLandscapeLeft</string>
            <string>UIInterfaceOrientationLandscapeRight</string>
        </array>
    </dict>
</plist>

How can I check to see if the data is being "replaced" or overwritten by the now encrypted data? I tried to then insert a log of the file contents before this method gets called to see if it would retrieve and show encrypted plist data, but it does not. I am not sure if that's because it is just reading the data from the plist in the main bundle, or the writeToFile is not doing what I need. Thanks!

UPDATE This is for the average user trying to get hold of my apps data so that they could potentially be able to see the plist as a mess of encryption rather than all of the plain text plist data.

Solution

  • If you want to have encrypted data delivered with your application, it needs to be encrypted during the build process, not during runtime. The easiest way to do this is to encrypt the file however you want and then add it to your Xcode project as a resource. You then read it as an NSData as you would any other resource and decrypt in memory.