They bought the tool from Cellebrite.
It’s hardly a secret.
Cellebrite was prominent in cracking Trayvon Martin’s phone.
They are the go to company for law enforcement when it comes to getting data off of mobile devices.
Why the FBI was unaware of them, is anyone’s guess.
Cellebrite can likely crack the latest phones, if you pay for them to do so.
Highly doubtful. As late as November, The Hacking Team, a European forensic company, was offering a $1 million bounty for a hack that would break the Secure Enclave of the iPhone 5S and later. It went unclaimed.
(No, before someone asserts I am wrong, the $1 million bounty that WAS claimed in October was for a remote JAILBREAK of an already unlocked iPhone running iOS 9, which is NOT the same bounty for unlocking an LOCKED iPhone. Apple closed that vulnerability three weeks after the bounty was awarded to a team of hackers.)
Were it possible to unlock later iOS devices with such ease, there would NOT be hundreds of iOS devices stored in evidence lockers around the world waiting for such a tool. These Forensic IT companies are in the business of making money by unlocking mobile devices. . . they'd be unlocked.