3 ms·

Apple solves the problem in hardware by streaming the persistent storage data through dedicated silicon. Not only is this extremely fast, it guards the key. For

Apple solves the problem in hardware by streaming the persistent storage data through dedicated silicon. Not only is this extremely fast, it guards the key. For the Intel versions of Mac, this was done in the T2 coprocessor.

purkka 2y ago
The flipside of this is availability. Your T2 coprocessor is now permanently tied to your data. This means if the chip dies, there's no recovery unless you have a backup encrypted with a separate key (with its own confidentiality/availability tradeoff). (And if anything else on your motherboard dies, Apple's official answer is "you're f*cked", since they refuse to do board-level repair.) For the threat model of most users, where hardware-based targeted attacks aren't a big concern, this is a bad tradeoff.
- dmitrygr 2y ago
  > if the chip dies, I've heard of zero T2s dying. I've hard of android data recovered (TFA)
- ajross 2y ago
  It's sort of a weird space we're in in the modern world, where you have to assume that anything on a "device" is ephemeral and fragile, and those of us concerned with data persistence on local hardware need to work at having a path to verifiably-restorable backups. Cloud is a great solution for most people. But not really an option for "where do I put my decades-stale collection of old home directories" or "mbox files from email in the late 90's".
- wesamco 2y ago
  > For the threat model of most users, where hardware-based targeted attacks aren't a big concern, this is a bad tradeoff. > hardware-based targeted attacks You mean physical-access attacks, correct? Is it really just these kinds of attacks that a T2 chip protects against? AFAIK if malware has super user privilege, it can access the RAM of other processes, and therefore it can access the encryption keys stored in RAM by other processes. If those processes could have used an encryption API that does the encryption on the chip, and therefore not need to store encryption keys in RAM, they'd be protected against this kind of attack, a kind of attack that is not hardware-based.
  - moe_sc 2y ago
    Considering those keys are loaded into RAM for/whilst unencripting, i don't see how it matters, cause the malware should have access to the (now) unencripted data regardless.
curt15 2y ago
Is that how self-encrypting SSDs also work?
- WirelessGigabit 2y ago
  No, I found this a good explanation: https://www.lullabot.com/articles/adventures-with-edrive-accelerated-ssd-encryption-on-windows https://www.lullabot.com/articles/adventures-with-edrive-acc...
dangerclose 2y ago
my colleagues' mbp m2 got into recovery mode after sonoma 14.3 update. it is mdm managed and the recovery key got from the IT is not able to decrypt the disk. login accounts tied to the drive also not able to unlock the disk. IT reached out to apple support and waiting response. because of silicon no other methods like in intel, getting into the machine works. does that mean no way of getting the data back? is it possible to install a fresh mac installation on a external disk and access mbp internal disk for decrypting?
- KennyBlanken 2y ago
  Why does your IT department MDM devices but not have backups and/or why is any substantial amount of data not synced to servers, in repos, etc? Given how fast networks and storage and processors are these days - if something takes more than an hour or two of diagnostic time and rarely happens, you just nuke the machine and re-image.

purkka 2y ago

The flipside of this is availability. Your T2 coprocessor is now permanently tied to your data. This means if the chip dies, there's no recovery unless you have a backup encrypted with a separate key (with its own confidentiality/availability tradeoff). (And if anything else on your motherboard dies, Apple's official answer is "you're f*cked", since they refuse to do board-level repair.) For the threat model of most users, where hardware-based targeted attacks aren't a big concern, this is a bad tradeoff.

dmitrygr 2y ago
> if the chip dies, I've heard of zero T2s dying. I've hard of android data recovered (TFA)
ajross 2y ago
It's sort of a weird space we're in in the modern world, where you have to assume that anything on a "device" is ephemeral and fragile, and those of us concerned with data persistence on local hardware need to work at having a path to verifiably-restorable backups. Cloud is a great solution for most people. But not really an option for "where do I put my decades-stale collection of old home directories" or "mbox files from email in the late 90's".
wesamco 2y ago
> For the threat model of most users, where hardware-based targeted attacks aren't a big concern, this is a bad tradeoff. > hardware-based targeted attacks You mean physical-access attacks, correct? Is it really just these kinds of attacks that a T2 chip protects against? AFAIK if malware has super user privilege, it can access the RAM of other processes, and therefore it can access the encryption keys stored in RAM by other processes. If those processes could have used an encryption API that does the encryption on the chip, and therefore not need to store encryption keys in RAM, they'd be protected against this kind of attack, a kind of attack that is not hardware-based.
- moe_sc 2y ago
  Considering those keys are loaded into RAM for/whilst unencripting, i don't see how it matters, cause the malware should have access to the (now) unencripted data regardless.

curt15 2y ago

Is that how self-encrypting SSDs also work?

WirelessGigabit 2y ago
No, I found this a good explanation: https://www.lullabot.com/articles/adventures-with-edrive-accelerated-ssd-encryption-on-windows https://www.lullabot.com/articles/adventures-with-edrive-acc...

dangerclose 2y ago

my colleagues' mbp m2 got into recovery mode after sonoma 14.3 update. it is mdm managed and the recovery key got from the IT is not able to decrypt the disk. login accounts tied to the drive also not able to unlock the disk. IT reached out to apple support and waiting response. because of silicon no other methods like in intel, getting into the machine works. does that mean no way of getting the data back? is it possible to install a fresh mac installation on a external disk and access mbp internal disk for decrypting?

KennyBlanken 2y ago
Why does your IT department MDM devices but not have backups and/or why is any substantial amount of data not synced to servers, in repos, etc? Given how fast networks and storage and processors are these days - if something takes more than an hour or two of diagnostic time and rarely happens, you just nuke the machine and re-image.