Technology Review’s Simson L. Garfinkel takes a look at how Apple’s security measures have evolved since its debut, from being an “embarrassing flub” to almost unbreakable.
In the article, titled “The iPhone has passed a key security threshold,” Garfinkel details how the 256-bit AES encryption used in iOS devices makes it acceptable for use in government organisations and enterprise.
In fact, in its efforts to make its devices more secure, Apple has crossed a significant threshold. Technologies the company has adopted protect Apple customers’ content so well that in many situations it’s impossible for law enforcement to perform forensic examinations of devices seized from criminals. Most significant is the increasing use of encryption, which is beginning to cause problems for law enforcement agencies when they encounter systems with encrypted drives.
He quotes a Department of Justice employee as saying:
“I can tell you from the Department of Justice perspective, if that drive is encrypted, you’re done. When conducting criminal investigations, if you pull the power on a drive that is whole-disk encrypted you have lost any chance of recovering that data.”
The AES encryption algorithm used in iOS devices is secure as long as the keys remain unknown to third parties that try to gain unauthorised access to the device. Apple assigns each iOS device a unique 256 bit key that is burned onto the processor and unreadable to any sort of software. Even Apple doesn’t keep a copy of the key, which means that law enforcement agencies can’t force the company into giving up keys for devices they need to conduct investigations on. The encryption-decryption is computationally intensive, which is why Apple has dedicated hardware in place to perform this task.
A natural consequence of data being encrypted with a device specific key is that physical storage, moved from one iOS device to another, is impossible to read. More details about security measures in iOS can be found in this whitepaper published by Apple a few months ago.
A copy of the 256-bit AES key is stored in device’s flash memory to enable decryption, but that is itself encrypted with the passcode set by the user. Unless the passcode is entered, the key stored on memory can’t be retrieved, which in turn means that the data stored can’t be read.
The article also notes that Android’s security measures aren’t nearly as good as iOS, as the security key is not stored in flash memory in case of Android devices.