4 ms·

This is contradicted within the linked research: >The same approach could be applied to the newer models of iPhone. The same type of LGA60 NAND chips ar

by sigmar 10y ago

This is contradicted within the linked research: >The same approach could be applied to the newer models of iPhone. The same type of LGA60 NAND chips are used up to the iPhone 6 Plus. Any attacker with sufficient technical skills could repeat the experiments. Newer iPhones will require more sophisticated equipment and FPGA test board

xmodem 10y ago
The iOS security guide would appear to contradict this: https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf > 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. This is not super specific, but would imply that the secure enclave has its own storage.
abalone 10y ago
They are wrong. The A7 added a hardware passcode attempt counter that would defeat their method.[1] And that's not all. With the introduction of Touch ID, Apple has shifted to 6 digit passcodes as the standard. The authors note that their method would not work so well, even if they had infinite time: "Given six attempts per each rewrite this method would require at most 1667 rewrites to find a 4-digit passcode. For a 6-digit passcode it would require over 160 thousand rewrites and will very likely damage the Flash memory storage." If you want to decrypt the modern iPhone you'd probably have to try to poke inside of the secure enclave with an SEM or something. And then you're getting into the realm of hardware defenses against this kind of intrusion, like physical self-destruction when probed.. not sure if Apple's doing anything there but it's crazy stuff. [1] https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf (page 12)
- rasz_pl 10y ago
  You dont need to constantly rewrite flash, you can emulate it with fpga. In-Circuit eprom emulation is old as a rock.
  - abalone 10y ago
    That's a fair point, but it's not the method they used, and even if it were feasible to implement the secure enclave passcode attempt counter would still render it ineffective.

by sigmar 10y ago

xmodem 10y ago

The iOS security guide would appear to contradict this: https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf > 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. This is not super specific, but would imply that the secure enclave has its own storage.

abalone 10y ago

They are wrong. The A7 added a hardware passcode attempt counter that would defeat their method.[1] And that's not all. With the introduction of Touch ID, Apple has shifted to 6 digit passcodes as the standard. The authors note that their method would not work so well, even if they had infinite time: "Given six attempts per each rewrite this method would require at most 1667 rewrites to find a 4-digit passcode. For a 6-digit passcode it would require over 160 thousand rewrites and will very likely damage the Flash memory storage." If you want to decrypt the modern iPhone you'd probably have to try to poke inside of the secure enclave with an SEM or something. And then you're getting into the realm of hardware defenses against this kind of intrusion, like physical self-destruction when probed.. not sure if Apple's doing anything there but it's crazy stuff. [1] https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf (page 12)

rasz_pl 10y ago
You dont need to constantly rewrite flash, you can emulate it with fpga. In-Circuit eprom emulation is old as a rock.
- abalone 10y ago
  That's a fair point, but it's not the method they used, and even if it were feasible to implement the secure enclave passcode attempt counter would still render it ineffective.