The combination of security methods built into Apple's iOS mobile operating system make it practically impossible to crack, according to the National Security Agency's standards, reports Technology Review.
The security built into iOS is so effective for a number of reasons, including the fact that its user-friendly design makes it easy for even not-so-tech savvy consumers to use encryption on their phones. Apple's security architecture uses the Advanced Encryption Standard algorithm (AES), which is a data-scrambling system first published in 1998. It was adopted as a U.S. government standard in 2001, and more than a decade later, it is considered unbreakable. Technology Review points out that "the algorithm is so strong that no computer imaginable for the foreseeable future - even a quantum computer - would be able to crack a truly random 256-bit AES key.
The AES key used in every iOS device "is unique to each device and is not recorded by Apple or any of its suppliers," reads a security white paper from Apple. When iOS devices are turned off, the encryption key in the computer's accessible memory is erased, so someone attempting to break into an iOS device would have to try all possible keys, which is the task considered impossible by the NSA.
It wasn't always like this, of course. On the original iPhone, every mobile app made by Apple ran with root privileges, giving hackers huge opportunities to exploit bugs in the apps and take over the phone. This design flaw was fixed in January 2008, after which Apple began investing heavily in iOS security.
Even more details on the security of iOS can be read at Technology Review.
Source: Technology Review