effaceable

An attacker would instead image the flash, grab the Dkey from effaceable storage, and decrypt the filesystem.

To address this issue, iOS devices include a feature dedicated to secure data erasure called Effaceable Storage.

Im not sure slamming ram on a pcie card is a better solution than including a piece of effaceable storage somewhere.

One is (probably) easy for Apple to extract (the randomly generated, re-writable value in effaceable storage) and the other is (supposedly) very difficult to extract, because it's burned into the CPU hardware.

Actually, the parent is correct - the PDF you linked suggests otherwise: > (NSFileProtectionNone): This class key is protected only with the UID, and is kept in Effaceable Storage.

The SE does enforce the escalating timeouts, and probably the wipe after ten tries, but that wipe could just be the SE telling the Effaceable Storage to erase the key.

If it turns out that the auto-erase feature is on, and the Effaceable Storage gets erased, they can remove the chip, copy the original information back in, and replace it.

Third speaker: Hi this is <?> and while this is also not my field I'm an ally and I can tell you what's been presented to us (the AMA governing body) from the APA is what they ave determined as effaceable procedure.

> If it turns out that the auto-erase feature is on, and the Effaceable Storage gets erased, they can remove the chip, copy the original information back in, and replace it.

To successfully parallelize an attack on an iPhone's passcode, you would have to A) get the key out of effaceable storage (can probably be done with a root 0day) and B) extract the HSM's burned-in crypto key (would require a decapping or maybe differential power analysis).

The Apple encryption specification claims to use a combination of: A)The encryption key burned into the chip's internal HSM B)A randomly generated encryption key in effaceable storage C)The user's passcode Each passcode attempt is protected by 250,000 rounds of some key stretching function (can't remember what exactly) using the device's internal crypto acceleration hardware.

While >>it doesn’t provide protection if an attacker has physical possession of a device<<, keys held in Effaceable Storage can be used as part of a key hierarchy to facilitate fast wipe and forward security (emphasis mine) However, it appears that the FBI attack only worked because the people in question used the 4 digit pin.

The article I have linked describes a specific technical workaround for avoiding permanent deletion of data, namely, avoiding deletion in “Effaceable Storage” of a key that encrypts some filesystem data.

The wrapped keys I mentioned are stored in what apple calls "effaceable storage", specially designated non-volatile memory that actually erases rather than just being marked as free.

> The “Erase all content and settings” option in Settings obliterates all the keys in Effaceable Storage, rendering all user data on the device cryptographically inaccessible.

With 14 million combinations just in a 4 character alphanumeric(upper/lower/numbers) password, I would think they would start to encounter flash reliability issues re-writing this "Effaceable Storage" long before the password could be broken.