An error locked the San Bernardino Attacker’s iPhone, What!


The head of the FBI acknowledged in court that his agency lost a chance to capture data from the iPhone used by one of the San Bernardino attackers when it ordered that the password to the Apple iCloud be reset shortly after the rampage without asking Apple technical resources for help.
FBI personnel apparently believed that by resetting the Apple iCloud password, they could get access to information stored on the iPhone. Instead, the change had the opposite effect, locking them out and eliminating other means of gaining access to data.
The FBI rejected the idea expressed by several lawmakers that the FBI is attempting to force Apple to build software to decrypt or by pass its own security features. A different analogy was used to explain the government’s demands –
“There’s already a door on that iPhone,”
“Essentially, we’re asking Apple to remove the vicious guard dog and let us pick the lock.”
The FBI does not understand the meaning of a “Secure Enclave”.
And, how near impossible it is to circumvent a “Secure Enclave”. Not only would it require Apple to develop software, hire some of the best minds in the world and still their is a very real possibility the effort will fail.

And, let’s not forget the FBI request is expressly against federal law (details, details). 

iPhones use the ARM A7 processor

There are numerous reasons Apple uses the A7 processor. To economically create the Secure Enclave, Apple needed a processor that was already aware of the concept of encryption and security at a native level and has the dedicated hardware to make a segregated and secure area with in the processor architecture. 
This white paper written by ARM in 2008 shows the A7 was designed for mobile payments [6]: 

“6.2.2 Mobile Payment

Many embedded devices are now storing a large amount of user data, including sensitive information such as synchronised email, mobile banking details, and mobile payment credentials. This user data can be protected, requiring the entry of passcode before it can be used, however once unlocked it is vulnerable to any weakness in the underlying software environment.

Migrating the data storage, data manipulation, and even the passcode entry, into the Secure world makes sense for many applications that make use of user data. While all of these use cases have subtly different assets, they all share a similar security requirements. For the purposes of this example, Gadget2008 will use mobile payment which has stricter requirements than most of the other use cases.”


How Does The Secure Enclave Work?

Security  is achieved by partitioning all of the hardware and software resources so that they exist in one of two worlds – the Secure world for the security subsystem or the normal world for everything else. The TrustZone-enabled AMBA3 AXI bus fabric ensures that normal world components can not access Secure world components, enabling construction of a strong perimeter boundary between the two.

Hardware Architecture of TrustZone.

This design places sensitive components in the Secure world, and implements robust software running on the secure processor cores, to protect assets against many possible attacks, including those which are normally difficult to secure.  By separating security sensitive peripherals through hardware this limits the number of sub-systems that need to go through security evaluation.


Software Architecture of TrustZone

The iPhone A7 processor is optimized for Secure Mobile Payments. It would require exceptional skills and resources to attempt access to data stored in a Secure Enclave. 

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