How to protect iOS bundle files like plist ,image,sqlite,media files - ios

Question

I have created sample hello world project and then added Data.plist file to resource folder.
Now people can easily get the bundle files by unzipping the .ipa file. Is there any ways to protect the Data.plist file that saved in the application bundle of iPhone app?
Encryption is a decent method of scrambling the data but i don't know how to implement encription concept.
Do you have any sample code?
NSString *filePath = [[NSBundle mainBundle] pathForResource:#"Data" ofType:#"plist"];
NSArray *arrData = [[NSArray alloc]initWithContentsOfFile:filePath];
NSData *datas = [NSKeyedArchiver archivedDataWithRootObject:arrData];
[datas writeToFile:filePath atomically:YES];
After extracting IPA file

Answer 1

encrypt the files on the mac... during deployment:
FIRST: don't add the files to be encrypted to the target
e.g. Encryption-Test.plist
THEN add a shell script phase to your xcode project to use openssl to encrypt&copy the files.
e.g.
openssl enc -e -aes-256-cbc -pass pass:asdasd
-in $PROJECT_DIR/test/Encryption-Test.plist
-out $TARGET_BUILD_DIR/$UNLOCALIZED_RESOURCES_FOLDER_PATH/Encryption-Test.enc
add RNCryptor source files from github to your project. This makes decryption of openSSL encrypted AES files really easy. (Thanks rob!) https://github.com/RNCryptor/RNCryptor
(Apple's CCrypt api isn't nice to work with directly)
load the data and decrypt it:
e.g.
#implementation TestViewController
- (void)viewDidLoad
{
[super viewDidLoad];
NSString *path = [[NSBundle mainBundle] pathForResource:#"Encryption-Test" ofType:#"enc"];
NSData *passEncryptedData =[[NSData alloc] initWithContentsOfFile:path];
NSString *pass = #"asdasd";
NSData *dataDecrypted = [RNOpenSSLDecryptor decryptData:passEncryptedData withSettings:kRNCryptorAES256Settings password:pass error:nil];
id plist = [NSPropertyListSerialization propertyListFromData:dataDecrypted mutabilityOption:NSPropertyListImmutable format:nil errorDescription:nil];
assert(plist);
self.text.text = [plist description];
}
#end
added full sample: https://github.com/Daij-Djan/encryptBundleFiles

Answer 2

I struggled with the above examples with no success and finally found some code that lets you decrypt an encrypted file (any file in fact) with openssl. I'm working in the documents folder for this example and I'm not using any shell scripting. Here's how to do it:
Encrypt your file in the Terminal like so:
openssl aes-256-cbc -in questions.plist -out questions.enc
Add the file(s) to your Xcode project by dragging them to the Supporting Files directory
Download the RNCryptor library here.
Find the RNCryptor library in the downloaded project: encryptBundleFiles-master/test/RNCryptor and add them into to your Xcode project
Import the RNDecryptor.h and RNOpenSSLDecryptor.h files into your class file, like ExampleViewController.m file.
Add the code below from where you want to call it, like a certain function.
And you're done. You can now use the plist file to for example populate a tableview.
// Copy the plist file from the resources folder to the documents folder
NSFileManager *fileManager = [NSFileManager defaultManager];
NSError *error;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *txtPath = [documentsDirectory stringByAppendingPathComponent:#"questions.enc"];
if ([fileManager fileExistsAtPath:txtPath] == NO) {
NSString *resourcePath = [[NSBundle mainBundle] pathForResource:#"questions" ofType:#"enc"];
[fileManager copyItemAtPath:resourcePath toPath:txtPath error:&error];
}
NSString *filePath1 = [documentsDirectory stringByAppendingPathComponent:#"questions.encr"];
NSData *passEncryptedData =[[NSData alloc] initWithContentsOfFile:filePath1] ;
NSString *pass = #"asdf"; // Insert your password from step 1
NSData *dataDecrypted = [RNOpenSSLDecryptor decryptData:passEncryptedData withSettings:kRNCryptorAES256Settings password:pass error:&error];
NSString *appFile = [documentsDirectory stringByAppendingPathComponent:#"questionsDECRYPTED.plist"]; //The Decrypted file saved here
[dataDecrypted writeToFile:appFile atomically:YES];

Answer 3

Based on Daij-Dan's solution, I created a couple of Swift String extensions. Requires RNCryptor
They are used like this:
//Decrypt a UIImage
let decryptedImage = "encyptedFileNameInBundle".decryptedImage(password: "test")
//Decrypt NSData
let decryptedData = "encyptedDataFileNameInBundle".decryptedData(password: "test")
The string is the file name of the resource that has been added to the bundle resources. It assumes the file has an "enc" extension by default, otherwise, pass the file extension with "fileExtension:".
Extension:
public extension String {
func decryptedImage(password: String, fileExtension: String = "enc") -> UIImage? {
//create encypted file with:
//openssl aes-256-cbc -in fileName.jpg -out fileName.enc
if let decryptedData = self.decryptedData(password: password, fileExtension: fileExtension) {
return UIImage(data: decryptedData)
}
return nil
}
func decryptedData(password: String, fileExtension: String = "enc") -> Data? {
//create encypted file with:
//openssl aes-256-cbc -in fileName.data -out fileName.enc
if let fileURL = Bundle.main.url(forResource: self, withExtension: fileExtension) {
do {
let encyptedData = try Data(contentsOf: fileURL)
return try RNOpenSSLDecryptor.decryptData(encyptedData, with: kRNCryptorAES256Settings, password: password)
} catch {
print("encryptedImage ERR: \(error.localizedDescription)")
}
}
return nil
}
}

Answer 4

Use a NSKeyedArchiver to create an NSData object from your dictionary (NSKeyedArchiver archivedDataWithRootObject:). Then encrypt the NSData with AES and write that to your file.
Reading just the reverse process: first, read the NSData, decrypt it via the method from the mentioned link, then pass the decrypted NSData to NSKeyedUnarchiver (NSKeyedUnarchiver unarchiveObjectWithData:) and you get your dictionary back. That you can use for plist file or as NSDictionary to keep your data safe.
Example 1:
Example 2:
EDIT 2:
NSDictionary *Your_NSDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
#"Obj1", #"Key1",
#"Obj2", #"Key2", nil];
//store dictionary
NSMutableData *yourData = [[NSMutableData alloc] init];
NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
[archiver encodeObject:Your_NSDictionary forKey: #"key"];
[archiver finishEncoding];
[yourData writeToFile:#"FilePath" atomically:YES];
or
NSString* filePath = [[NSBundle mainBundle] pathForResource:#"Data"
ofType:#"plist"];
NSDictionary* data = [NSDictionary dictionaryWithContentsOfFile:filePath];
NSMutableDictionary * rootObject;
rootObject = [NSMutableDictionary dictionary];
[rootObject setValue: data forKey:#"accounts"];
[NSKeyedArchiver archiveRootObject: rootObject toFile: path];