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But if I can update the firmware to make it easier to brute-force the pin, that's bad. Previously there was speculation that a firmware update to the secure enc

But if I can update the firmware to make it easier to brute-force the pin, that's bad. Previously there was speculation that a firmware update to the secure enclave would wipe the contents of the secure enclave. If that's not the case, then the whole design of a simple pin combined with a complex device id to form a secure key is not as strong as was thought. Basically, everyone should now use an alphanumeric password on their phones and not rely on the 10-tries limit or on the exponentially increasing delays.

nathancahill 11y ago
Sounds like you know something the FBI is missing in the San Bernadino case! Definitely shoot them an email about how updating the firmware makes it easier to brute-force the pin.
- feld 11y ago
  These internet/armchair secure enclave experts are starting to ruin every conversation
  - seanp2k2 11y ago
    I trust that comex knows what he's talking about : http://www.ijailbreak.com/developers/ http://www.ijailbreak.com/developers/
    - feld 11y ago
      I will require more specific details of the iPhone 5/5C architecture to confirm this is true. Schematics, Apple documents, etc would be nice.
- gpm 11y ago
  The FBI is currently trying to force Apple to produce the modified firmware he is talking about. I'm not sure why you think he is suggesting he knows more than them.
- mikeash 11y ago
  Discussion of the Secure Enclave has no bearing on the practicality of the FBI's request. The iPhone the FBI is asking Apple to break into is an older model that doesn't have a Secure Enclave. It's pretty well accepted at this point that Apple is capable of complying with the FBI's request. The big question is whether Apple would be capable of complying with a similar request with a newer iPhone that includes a Secure Enclave.
feld 11y ago
The iPhone 5/5C does not have a secure enclave. That was a feature of the A7 chip in the 5S and newer. This is how it's possible for Apple to modify the phone's firmware without wiping the phone. I suspect that the iPhone 5/5C and older's encryption key was stored on a regular flash chip somewhere. edit: the "firmware" update is an iOS update that removes the software limitation. SOFTWARE LIMITATION. On newer iPhones it's hardware (secure enclave). Yes, you can do an firmware update on an encrypted iPhone. It's not full disk encryption. Only user data is encrypted.
- comex 11y ago
  This is incorrect - the Secure Enclave is a separate CPU, but the rate limiter is still software, and its firmware can (currently) be updated without erasing keys: http://blog.trailofbits.com/2016/02/17/apple-can-comply-with-the-fbi-court-order/ http://blog.trailofbits.com/2016/02/17/apple-can-comply-with...
nemothekid 11y ago
The phone in the San Bernardino case is an iPhone 5C which does not have a Secure Enclave. The Secure Enclave (in the iPhone 5S and iPhone 6) has a hardware enforced rate limiter that cannot be overridden by a firmware update.
- comex 11y ago
  This is incorrect - the Secure Enclave is a separate CPU, but the rate limiter is still software, and its firmware can (currently) be updated without erasing keys: http://blog.trailofbits.com/2016/02/17/apple-can-comply-with-the-fbi-court-order/ http://blog.trailofbits.com/2016/02/17/apple-can-comply-with...
  - threeseed 11y ago
    The rate limiter is in software but that doesn't mean the total number of attempts is in software. Or that there isn't a minimum rate set in hardware. All we know is that Apple at some point increased the delay. Doesn't mean they can decrease it.
  - sjwright 11y ago
    This article seems to be largely unsubstantiated speculation. I see no evidence that a locked secure enclave can have its firmware updated.
  - mikeash 11y ago
    Where is the evidence that the Secure Enclave's software can be updated without erasing keys? The article states: "Apple can update the SE firmware, it does not require the phone passcode, and it does not wipe user data on update." But it does not support this statement in any way. In my experience, it does either require the phone passcode, or it wipes the data. Of course, I have no idea where that requirement is implemented. It would be easy and sensible to have the secure enclave require the passcode for an update to its own firmware, or erase the keys it holds when applying such an update without the passcode. Apple doesn't say they do it from what I can tell, but it would fit with everything else they do, it's pretty easy to do, and I've seen no indication that it doesn't do this.
metric10 11y ago
Assuming you are referring to the San Bernardino case, that is an iPhone 5c which features an A6 series CPU. The Secure Enclave feature was introduced with the A7 [1]. [1] https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf (page 5)
- tlrobinson 11y ago
  The point is, it was speculated that if the phone had a Secure Enclave it would be impossible for Apple to meet the FBI's request, but it appears that even Secure Enclave phones are vulnerable.
  - threeseed 11y ago
    > but it appears that even Secure Enclave phones are vulnerable What proof is there of this ? Even reports I've heard from people at the White House believe the newer phones are simply not possible for Apple to compromise.
    - metric10 11y ago
      This appears to be true. If you look at Page 5 of [1], there's a side note about DFU mode. There's no indication that updating the firmware wipes the secure contents of the device, which it would need to in order to be secure: """ Entering Device Firmware Upgrade (DFU) mode Restoring a device after it enters DFU mode returns it to known good state with the certainty that only unmodified Apple-signed code is present. DFU mode can be entered manually: First connect the device to a computer using a USB cable, then hold down both the Home and Sleep/Wake buttons. After 8 seconds, release the Sleep/Wake button while continuing to hold down the Home button. Note: Nothing will be displayed on the screen when the device is in DFU mode. If the Apple logo appears, the Sleep/Wake button was held down too long. """ [1] https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf
      - acdha 11y ago
deleted 11y ago
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givinguflac 11y ago
You CANNOT update the firmware on the secure enclave. You don't understand how it works obviously.

nathancahill 11y ago

Sounds like you know something the FBI is missing in the San Bernadino case! Definitely shoot them an email about how updating the firmware makes it easier to brute-force the pin.

feld 11y ago
These internet/armchair secure enclave experts are starting to ruin every conversation
- seanp2k2 11y ago
  I trust that comex knows what he's talking about : http://www.ijailbreak.com/developers/ http://www.ijailbreak.com/developers/
  - feld 11y ago
    I will require more specific details of the iPhone 5/5C architecture to confirm this is true. Schematics, Apple documents, etc would be nice.
gpm 11y ago
The FBI is currently trying to force Apple to produce the modified firmware he is talking about. I'm not sure why you think he is suggesting he knows more than them.
mikeash 11y ago
Discussion of the Secure Enclave has no bearing on the practicality of the FBI's request. The iPhone the FBI is asking Apple to break into is an older model that doesn't have a Secure Enclave. It's pretty well accepted at this point that Apple is capable of complying with the FBI's request. The big question is whether Apple would be capable of complying with a similar request with a newer iPhone that includes a Secure Enclave.

feld 11y ago

The iPhone 5/5C does not have a secure enclave. That was a feature of the A7 chip in the 5S and newer. This is how it's possible for Apple to modify the phone's firmware without wiping the phone. I suspect that the iPhone 5/5C and older's encryption key was stored on a regular flash chip somewhere. edit: the "firmware" update is an iOS update that removes the software limitation. SOFTWARE LIMITATION. On newer iPhones it's hardware (secure enclave). Yes, you can do an firmware update on an encrypted iPhone. It's not full disk encryption. Only user data is encrypted.

comex 11y ago
This is incorrect - the Secure Enclave is a separate CPU, but the rate limiter is still software, and its firmware can (currently) be updated without erasing keys: http://blog.trailofbits.com/2016/02/17/apple-can-comply-with-the-fbi-court-order/ http://blog.trailofbits.com/2016/02/17/apple-can-comply-with...

nemothekid 11y ago

The phone in the San Bernardino case is an iPhone 5C which does not have a Secure Enclave. The Secure Enclave (in the iPhone 5S and iPhone 6) has a hardware enforced rate limiter that cannot be overridden by a firmware update.

comex 11y ago
This is incorrect - the Secure Enclave is a separate CPU, but the rate limiter is still software, and its firmware can (currently) be updated without erasing keys: http://blog.trailofbits.com/2016/02/17/apple-can-comply-with-the-fbi-court-order/ http://blog.trailofbits.com/2016/02/17/apple-can-comply-with...
- threeseed 11y ago
  The rate limiter is in software but that doesn't mean the total number of attempts is in software. Or that there isn't a minimum rate set in hardware. All we know is that Apple at some point increased the delay. Doesn't mean they can decrease it.
- sjwright 11y ago
  This article seems to be largely unsubstantiated speculation. I see no evidence that a locked secure enclave can have its firmware updated.
- mikeash 11y ago
  Where is the evidence that the Secure Enclave's software can be updated without erasing keys? The article states: "Apple can update the SE firmware, it does not require the phone passcode, and it does not wipe user data on update." But it does not support this statement in any way. In my experience, it does either require the phone passcode, or it wipes the data. Of course, I have no idea where that requirement is implemented. It would be easy and sensible to have the secure enclave require the passcode for an update to its own firmware, or erase the keys it holds when applying such an update without the passcode. Apple doesn't say they do it from what I can tell, but it would fit with everything else they do, it's pretty easy to do, and I've seen no indication that it doesn't do this.

metric10 11y ago

Assuming you are referring to the San Bernardino case, that is an iPhone 5c which features an A6 series CPU. The Secure Enclave feature was introduced with the A7 [1]. [1] https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf (page 5)

tlrobinson 11y ago
The point is, it was speculated that if the phone had a Secure Enclave it would be impossible for Apple to meet the FBI's request, but it appears that even Secure Enclave phones are vulnerable.
- threeseed 11y ago
  > but it appears that even Secure Enclave phones are vulnerable What proof is there of this ? Even reports I've heard from people at the White House believe the newer phones are simply not possible for Apple to compromise.
  - metric10 11y ago
    This appears to be true. If you look at Page 5 of [1], there's a side note about DFU mode. There's no indication that updating the firmware wipes the secure contents of the device, which it would need to in order to be secure: """ Entering Device Firmware Upgrade (DFU) mode Restoring a device after it enters DFU mode returns it to known good state with the certainty that only unmodified Apple-signed code is present. DFU mode can be entered manually: First connect the device to a computer using a USB cable, then hold down both the Home and Sleep/Wake buttons. After 8 seconds, release the Sleep/Wake button while continuing to hold down the Home button. Note: Nothing will be displayed on the screen when the device is in DFU mode. If the Apple logo appears, the Sleep/Wake button was held down too long. """ [1] https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf
    - acdha 11y ago

deleted 11y ago

[deleted]

givinguflac 11y ago

You CANNOT update the firmware on the secure enclave. You don't understand how it works obviously.