iphone sqlite encryption data

Question

I have created one small business application..In my application i have used sqlite database for storing the data.. Here I decided to use encryption method using security framework..I know about sqlite but i dont know how to implement sqlite encryption method...Please guide me....

Answer 1

The accepted answer by Shane Powell is incorrect.

Setting NSFileProtectionComplete for NSFileProtectionKey after addPersistentStoreWithType:configuration:URL:options:error: has no effect, i.e., the default setting (NSFileProtectionCompleteUntilFirstUserAuthentication) is applied, which is less secure.

The correct approach is to set NSFileProtectionComplete for NSPersistentStoreFileProtectionKey (note that this key is specific to the persistent store) in a dictionary passed for the options parameter...

NSDictionary *fileAttributes = @{NSPersistentStoreFileProtectionKey : NSFileProtectionComplete};

 if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:fileAttributes error:&error]) {
    ...

I tested this using PhoneView and was able to access the SQLite on a locked device after an initial unlock using the accepted answer's approach, but I could not access the SQLite on a locked device after an initial unlock using the approach I suggested.

Answer 2

You use the NSFileProtectionComplete feature (it's only available in ios 4 and greater).

Here is an example of creating a NSPersistentStoreCoordinator for example.sqlite which is encrypted if used on ios4.

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
    if (persistentStoreCoordinator != nil) {
        return persistentStoreCoordinator;
    }

    NSString *storePath = [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"example.sqlite"];
    NSURL *storeUrl = [NSURL fileURLWithPath:storePath ];

    NSError *error = nil;
    persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel: [self managedObjectModel]];
    if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:nil error:&error]) {
        // Handle error
    }

    if(RSRunningOnOS4OrBetter())
    {
        NSDictionary *fileAttributes = [NSDictionary dictionaryWithObject:NSFileProtectionComplete forKey:NSFileProtectionKey];
        if (![[NSFileManager defaultManager] setAttributes:fileAttributes ofItemAtPath:storePath error:&error]) {
            // Handle error
        }
    }

    return persistentStoreCoordinator;
}

BOOL RSRunningOnOS4OrBetter(void) {
    static BOOL didCheckIfOnOS4 = NO;
    static BOOL runningOnOS4OrBetter = NO;

    if (!didCheckIfOnOS4) {
        NSString *systemVersion = [UIDevice currentDevice].systemVersion;
        NSInteger majorSystemVersion = 3;

        if (systemVersion != nil && [systemVersion length] > 0) { //Can't imagine it would be empty, but.
            NSString *firstCharacter = [systemVersion substringToIndex:1];
            majorSystemVersion = [firstCharacter integerValue];         
        }

        runningOnOS4OrBetter = (majorSystemVersion >= 4);
        didCheckIfOnOS4 = YES;
    }
    return runningOnOS4OrBetter;
}