5 ms·

It shouldn't be particularly surprising that the two parts are cryptographically paired, the sensors for the IR camera and the HSM within the main processor are

It shouldn't be particularly surprising that the two parts are cryptographically paired, the sensors for the IR camera and the HSM within the main processor are extensions of the same security boundary effectively. If you could replace the sensor without something being unhappy, the system would be completely broken.

PostThisTooFast 5y ago
No, it wouldn't. The sensor is an imager. The back end, which interprets what it delivers, should be separate. This is more petty Apple bullshit.
- user-the-name 5y ago
  How can you trust that the sensor is actually delivering what it sees?
- neilalexander 5y ago
  I suspect this is actually something to do with the fact that the Face ID sensors are projecting unique patterns across different devices. From the Apple Platform Security document: > After the TrueDepth camera confirms the presence of an attentive face, it projects and reads thousands of infrared dots to form a depth map of the face along with a 2D infrared image. This data is used to create a sequence of 2D images and depth maps which are digitally signed and sent to the Secure Enclave. To counter both digital and physical spoofs, the TrueDepth camera randomises the sequence of 2D images and depth map captures and projects a device-specific random pattern. A portion of the Secure Neural Engine — protected within the Secure Enclave — transforms this data into a mathematical representation and compares that representation with the enrolled facial data. This enrolled facial data is itself a mathematical representation of the user’s face captured across a variety of poses. https://support.apple.com/en-gb/guide/security/sec067eb0c9e/1/web/1 https://support.apple.com/en-gb/guide/security/sec067eb0c9e/...
- simonh 5y ago
  The back end has to be able to trust the data from the sensor, and the only way to do that is engineer them as part of the same cryptographic trust domain. Otherwise you could just swap the sensor for a dummy device that presents whatever data you like to the back end. That would completely break the security model. I know a lot of the other phone manufacturers do stuff like this and think it's ok, but Apple knows what it's doing.
leereeves 5y ago
Apple doesn't have to permanently disable FaceID to maintain security; just require a password to log in after the screen has changed and reinitialize FaceID. And as another comment said "if the device detects any component has been tampered with, the user will be alerted during the first boot up".
- xwdv 5y ago
  That’s less secure.
  - oauea 5y ago
    Most secure would be for the device to go up in flames as soon as it detects any tampering. I sure wouldn't want to own such a device that could never be repaired.
  - spoonjim 5y ago
    No less secure than the regular OS, which always allows you to use the passcode rather than the FaceID.
- aj3 5y ago
  I guess they want to prevent someone from intercepting and tampering with a phone while it's being shipped to the customer, you know the supply chain attacks NSA (https://www.theverge.com/2013/12/29/5253226/nsa-cia-fbi-laptop-usb-plant-spy https://www.theverge.com/2013/12/29/5253226/nsa-cia-fbi-lapt...) and CIA (https://phys.org/news/2017-03-wikileaks-cia-hacks-apple-mac.html https://phys.org/news/2017-03-wikileaks-cia-hacks-apple-mac....) perfected.
  - leereeves 5y ago
    But there is a way to replace the screen without disabling FaceID (how Apple does it), and the NSA likely knows how to do that as well. Or if they don't, they could force Apple to do so secretly.
    - 5y ago
aj3 5y ago
Just to make it clear that this isn't a purely theoretical concern, it's how Windows Hello got bypassed this summer: https://www.wired.com/story/windows-hello-facial-recognition-bypass/ https://www.wired.com/story/windows-hello-facial-recognition...
deleted 5y ago
[deleted]
captainmuon 5y ago
But do they have to pair the sensors in each phone distinctly? I assume they have hardware security measures that you cannot just read out the keys from one of the sensors. So why not just put the same "key" in all of the official IR cameras? Then you could still swap cameras with official safe ones, but you could not build a fake replacement.
- neilalexander 5y ago
  The sensors are using unique patterns on each device. There would need to be a pairing between the TrueDepth camera and the Secure Enclave in order to account for this unique pattern. This is why you can't copy Face ID data from one device to another and expect it to work. From the Apple Platform Security document: > After the TrueDepth camera confirms the presence of an attentive face, it projects and reads thousands of infrared dots to form a depth map of the face along with a 2D infrared image. This data is used to create a sequence of 2D images and depth maps which are digitally signed and sent to the Secure Enclave. To counter both digital and physical spoofs, the TrueDepth camera randomises the sequence of 2D images and depth map captures and projects a device-specific random pattern. A portion of the Secure Neural Engine — protected within the Secure Enclave — transforms this data into a mathematical representation and compares that representation with the enrolled facial data. This enrolled facial data is itself a mathematical representation of the user’s face captured across a variety of poses. https://support.apple.com/en-gb/guide/security/sec067eb0c9e/1/web/1 https://support.apple.com/en-gb/guide/security/sec067eb0c9e/...
  - captainmuon 5y ago
    So the individual dot patterns are fixed in hardware? That's clever. (A former colleague of mine has a vaguely related patent. They create unique patterns inside of chips by applying (sputtering) material at an angle, which creates chaotic patterns that cannot be copied by lithography, so the chip is in principle unclonable.)

PostThisTooFast 5y ago

No, it wouldn't. The sensor is an imager. The back end, which interprets what it delivers, should be separate. This is more petty Apple bullshit.

user-the-name 5y ago
How can you trust that the sensor is actually delivering what it sees?
neilalexander 5y ago
I suspect this is actually something to do with the fact that the Face ID sensors are projecting unique patterns across different devices. From the Apple Platform Security document: > After the TrueDepth camera confirms the presence of an attentive face, it projects and reads thousands of infrared dots to form a depth map of the face along with a 2D infrared image. This data is used to create a sequence of 2D images and depth maps which are digitally signed and sent to the Secure Enclave. To counter both digital and physical spoofs, the TrueDepth camera randomises the sequence of 2D images and depth map captures and projects a device-specific random pattern. A portion of the Secure Neural Engine — protected within the Secure Enclave — transforms this data into a mathematical representation and compares that representation with the enrolled facial data. This enrolled facial data is itself a mathematical representation of the user’s face captured across a variety of poses. https://support.apple.com/en-gb/guide/security/sec067eb0c9e/1/web/1 https://support.apple.com/en-gb/guide/security/sec067eb0c9e/...
simonh 5y ago
The back end has to be able to trust the data from the sensor, and the only way to do that is engineer them as part of the same cryptographic trust domain. Otherwise you could just swap the sensor for a dummy device that presents whatever data you like to the back end. That would completely break the security model. I know a lot of the other phone manufacturers do stuff like this and think it's ok, but Apple knows what it's doing.

leereeves 5y ago

Apple doesn't have to permanently disable FaceID to maintain security; just require a password to log in after the screen has changed and reinitialize FaceID. And as another comment said "if the device detects any component has been tampered with, the user will be alerted during the first boot up".

xwdv 5y ago
That’s less secure.
- oauea 5y ago
  Most secure would be for the device to go up in flames as soon as it detects any tampering. I sure wouldn't want to own such a device that could never be repaired.
- spoonjim 5y ago
  No less secure than the regular OS, which always allows you to use the passcode rather than the FaceID.
aj3 5y ago
I guess they want to prevent someone from intercepting and tampering with a phone while it's being shipped to the customer, you know the supply chain attacks NSA (https://www.theverge.com/2013/12/29/5253226/nsa-cia-fbi-laptop-usb-plant-spy https://www.theverge.com/2013/12/29/5253226/nsa-cia-fbi-lapt...) and CIA (https://phys.org/news/2017-03-wikileaks-cia-hacks-apple-mac.html https://phys.org/news/2017-03-wikileaks-cia-hacks-apple-mac....) perfected.
- leereeves 5y ago
  But there is a way to replace the screen without disabling FaceID (how Apple does it), and the NSA likely knows how to do that as well. Or if they don't, they could force Apple to do so secretly.
  - 5y ago

aj3 5y ago

Just to make it clear that this isn't a purely theoretical concern, it's how Windows Hello got bypassed this summer: https://www.wired.com/story/windows-hello-facial-recognition-bypass/ https://www.wired.com/story/windows-hello-facial-recognition...

deleted 5y ago

[deleted]

captainmuon 5y ago

But do they have to pair the sensors in each phone distinctly? I assume they have hardware security measures that you cannot just read out the keys from one of the sensors. So why not just put the same "key" in all of the official IR cameras? Then you could still swap cameras with official safe ones, but you could not build a fake replacement.

neilalexander 5y ago
The sensors are using unique patterns on each device. There would need to be a pairing between the TrueDepth camera and the Secure Enclave in order to account for this unique pattern. This is why you can't copy Face ID data from one device to another and expect it to work. From the Apple Platform Security document: > After the TrueDepth camera confirms the presence of an attentive face, it projects and reads thousands of infrared dots to form a depth map of the face along with a 2D infrared image. This data is used to create a sequence of 2D images and depth maps which are digitally signed and sent to the Secure Enclave. To counter both digital and physical spoofs, the TrueDepth camera randomises the sequence of 2D images and depth map captures and projects a device-specific random pattern. A portion of the Secure Neural Engine — protected within the Secure Enclave — transforms this data into a mathematical representation and compares that representation with the enrolled facial data. This enrolled facial data is itself a mathematical representation of the user’s face captured across a variety of poses. https://support.apple.com/en-gb/guide/security/sec067eb0c9e/1/web/1 https://support.apple.com/en-gb/guide/security/sec067eb0c9e/...
- captainmuon 5y ago
  So the individual dot patterns are fixed in hardware? That's clever. (A former colleague of mine has a vaguely related patent. They create unique patterns inside of chips by applying (sputtering) material at an angle, which creates chaotic patterns that cannot be copied by lithography, so the chip is in principle unclonable.)