3 ms·
The author is absolutely, totally wrong. The PIN number is entangled with the device's 256-bit "UID", which itself is on-die in the SoC/CPU and NOT extractable
by teacup50 11y ago
The author is absolutely, totally wrong.
The PIN number is entangled with the device's 256-bit "UID", which itself is on-die in the SoC/CPU and NOT extractable without either being able to run code on the CPU, or decapping the SoC, reverse engineering its implementation, and extracting the UID, all from the SEM imagery.
The PIN number and the UID are fed to key derivation code for strengthening; the result of that process is used to actually perform encryption of the data on the NAND.
The weak point here is the PIN number; the FBI would be extremely hard-pressed to brute force the derived AES keys.
This is described in the "Tangling" definition on page 59 of the iOS Security Guide: https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf
I flagged the article, as the entire argument is predicated on a factually false premise.
- CPLX 11y agoFor what it's worth I unflagged/vouched for the article because I think the premise and the comments refuting it are an interesting discussion. Even if he's wrong, the reason why he's wrong is informative.
- lisper 11y agoThanks! I really did want to respond to this. It's possible that I'm wrong, but not for the reasons given so far. Once you have a copy of the flash you can always get back to the current state by installing a copy of the flash in its current state. Then you can simply brute-force the PIN.
- CPLX 11y agoIs that true though? Other commenters are arguing that the encryption of that flash chip is a value that, while based on the PIN, is sufficiently long as to resist brute force encryption. Is it possible that you're mistaken?
- lisper 11y agoOf course it's possible I'm mistaken. But not because of any of the reasons given here so far.
- msherry 11y agoHe's not claiming that you can brute-force the encryption key -- he's proposing another way to brute-force the PIN itself that won't trigger exponential timeouts or auto-wipe of the device. I don't know if he's right or wrong, but let's at least make sure we're clear what his argument is first.