While the legal maneuvering is interesting, I'd like to talk more about the technical mechanisms. Is it actually possible? Snowden said the FBI is full of shit

While the legal maneuvering is interesting, I'd like to talk more about the technical mechanisms. Is it actually possible? Snowden said the FBI is full of shit[1] and of course the phone is hackable, citing an ACLU report.[2] This report states that one could "easily" bypass the auto-erase-after-10-attempts function by popping out the Flash memory chip, copying its contents into some sort of test rig wired in its place, and then restoring it whenever it gets erased. This is an interesting modification of an attack scenario laid out in an excellent review of iPhone/iOS8 security by Matthew Green: "Since only the device itself knows UID -- and the UID can't be removed from the Secure Enclave -- this means all password cracking attempts have to run on the device itself. That rules out the use of FPGA or ASICs to crack passwords. Of course Apple could write a custom firmware that attempts to crack the keys on the device but even in the best case such cracking could be pretty time consuming, thanks to the 80ms PBKDF2 timing."[3] What this theoretical rig changes is it essentially allows a custom chip to run on the device (namely a delete-proof Flash chip), bypassing the need for Apple to write custom firmware. So a typical 6 digit one would take under a day to crack, based on the 80ms cost per attempt. So, it does seem possible to crack the pre-A7 phone in question with this rig. However, and here is where it gets interesting, Apple has said conflicting things about current phones. One the one hand, ever since the A7 they've added a hardware-level escalating time delay between failed passcode attempts: "On devices with an A7 or later A-series processor, the delays are enforced by the Secure Enclave. If the device is restarted during a timed delay, the delay is still enforced, with the timer starting over for the current period."[4] This would in theory make it infeasible to attempt this kind of rig on a current iPhone. Even a typical weak passcode would encounter an hour-long delay at least once every 10 attempts. It could take years to bruteforce all but the most predictable passcodes. However, Apple has also said that "Yes, it is certainly possible to create an entirely new operating system to undermine our security features as the government wants."[5] This would seem to suggest that software alone could enable bruteforcing, and this implication is in stark contrast to the statement on hardware defenses within the secure enclave. (Did they mean possible only on pre-A7 phones? It sure feels like they feel there's more at stake than that.) So I don't know what to believe at this point. The ACLU seems wrong in suggesting that this particular rig would work on anything but old pre-A7 iPhones, based on the current secure enclave's time delay. But Apple has outright stated that GovtOS could enable the cracking of iPhones. So... how? [1] https://twitter.com/Snowden/status/707299113449230336 https://twitter.com/Snowden/status/707299113449230336 [2] https://www.aclu.org/blog/free-future/one-fbis-major-claims-iphone-case-fraudulent https://www.aclu.org/blog/free-future/one-fbis-major-claims-... [3] http://blog.cryptographyengineering.com/2014/10/why-cant-apple-decrypt-your-iphone.html http://blog.cryptographyengineering.com/2014/10/why-cant-app... [4] https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf [5] http://www.apple.com/customer-letter/answers/ http://www.apple.com/customer-letter/answers/