3 ms·

Just one way I can think of would be to dump the contents of ROM chip, bruteforcing the encryption key by checking all possible PINs and comparing the decrypted

by jdiez17 11y ago

Just one way I can think of would be to dump the contents of ROM chip, bruteforcing the encryption key by checking all possible PINs and comparing the decrypted data against some known plaintext that would be present on all iOS devices. (this would require the FBI to know what key derivation algorithm is used on pre-secure-enclave devices, but that's not outside the realm of possibility).

abalone 11y ago
It's not that simple. The encryption key is not just the PIN. It's the PIN combined with a very strong unique key that is burned into the hardware, making hat particular brute force attack unfeasible.
- jdiez17 11y ago
  That's true for devices with a Secure Enclave, which the iPhone 5C does not have. As far as I know the key derivation is done entirely in software on older iPhones, but even if there was device-specific keying material it would be possible to dump that as well.
  - uxp 11y ago
    The CPU contains both the UID and GID on all iPhones (old and new). The Secure Enclave, if available, contains it's own UID for it's own key derivation. https://mikeash.com/pyblog/friday-qa-2016-02-19-what-is-the-secure-enclave.html https://mikeash.com/pyblog/friday-qa-2016-02-19-what-is-the-...
- droithomme 11y ago
  The machine id of the phone appears to be already known: https://www.eff.org/deeplinks/2016/02/technical-perspective-apple-iphone-case https://www.eff.org/deeplinks/2016/02/technical-perspective-... > From a technical standpoint, it would be possible to craft the cracking software to only run on Farook's phone by checking its hardware ID. The court order was actually quite specific that this is all that is being requested. Note that the court's order presupposes that the hardware ID is already available through some means. The court's order was crafted after a period of inquiry regarding actually technically feasible work. It's not certain how the machine id of a particular phone is known without being able to query it, but the case assumes it is known. The keyphrase is combined with the machine id and a hash is generated and compared against the stored hash to allow access. The stored password hash is stored on the flash drive and is readable since it's ordinary flash memory that can be directly read if one has physical access. So the hash and the machine id are available, and it is likely Apple uses a known and vetted secure hashing algorithm rather than roll their own. From this, one can do a brute force search using external computers to determine what the keyphrase is.
  - valleyer 11y ago
    There are different hardware IDs. Your quote is probably referring to something readily available through software like the UDID. The IDs necessary to decrypt the NAND are not readily accessible.

by jdiez17 11y ago

abalone 11y ago

It's not that simple. The encryption key is not just the PIN. It's the PIN combined with a very strong unique key that is burned into the hardware, making hat particular brute force attack unfeasible.

jdiez17 11y ago
That's true for devices with a Secure Enclave, which the iPhone 5C does not have. As far as I know the key derivation is done entirely in software on older iPhones, but even if there was device-specific keying material it would be possible to dump that as well.
- uxp 11y ago
  The CPU contains both the UID and GID on all iPhones (old and new). The Secure Enclave, if available, contains it's own UID for it's own key derivation. https://mikeash.com/pyblog/friday-qa-2016-02-19-what-is-the-secure-enclave.html https://mikeash.com/pyblog/friday-qa-2016-02-19-what-is-the-...
droithomme 11y ago
The machine id of the phone appears to be already known: https://www.eff.org/deeplinks/2016/02/technical-perspective-apple-iphone-case https://www.eff.org/deeplinks/2016/02/technical-perspective-... > From a technical standpoint, it would be possible to craft the cracking software to only run on Farook's phone by checking its hardware ID. The court order was actually quite specific that this is all that is being requested. Note that the court's order presupposes that the hardware ID is already available through some means. The court's order was crafted after a period of inquiry regarding actually technically feasible work. It's not certain how the machine id of a particular phone is known without being able to query it, but the case assumes it is known. The keyphrase is combined with the machine id and a hash is generated and compared against the stored hash to allow access. The stored password hash is stored on the flash drive and is readable since it's ordinary flash memory that can be directly read if one has physical access. So the hash and the machine id are available, and it is likely Apple uses a known and vetted secure hashing algorithm rather than roll their own. From this, one can do a brute force search using external computers to determine what the keyphrase is.
- valleyer 11y ago
  There are different hardware IDs. Your quote is probably referring to something readily available through software like the UDID. The IDs necessary to decrypt the NAND are not readily accessible.