First, enable the setting on your iPhone that erases all the phone’s data after 10 failed attempts to guess a passcode. The FBI doesn’t know whether Farook’s phone has that setting enabled (it’s off by default). What it wants from Apple is to create software that would turn the setting off, so it can try to break into the phone by using a “brute force” method: trying every possible passcode until it finds the one Farook chose.

However, the iPhone is built in such a way that even with brute-forcing, you can only try one passcode every 80 milliseconds (pdf, p. 12), or 750 tries a minute. The original iPhones had a four-digit numerical passcode, of which there are only 10,000 combinations. That would take a little over 13 minutes to crack. But on current iPhones you can use any combination of letters, numbers, and other characters, and as the passcode gets longer and more complex, the time taken to crack it rises pretty quickly:

And if you used a wider range of symbols—including uppercase letters, for instance—it would take even longer. Even an eight-digit numerical code takes three months to crack, while an eight-letter word takes about 529 years—meaning by the time the FBI cracked your phone, it would be dealing with about the 20th generation of your offspring.

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