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This is not true. You cannot just clone the data and run passcodes against it, because the data is not encrypted by your passcode. Instead, each file on iOS 11

This is not true. You cannot just clone the data and run passcodes against it, because the data is not encrypted by your passcode. Instead, each file on iOS 11 is encrypted with a different AES 256-bit key, and cracking even one 256-bit key through exhaustive search is thought to be out of reach of humankind (https://security.stackexchange.com/questions/6141/amount-of-simple-operations-that-is-safely-out-of-reach-for-all-humanity/6149#6149 https://security.stackexchange.com/questions/6141/amount-of-...). The file keys are wrapped by, among other things, the device's Unique ID, a 256-bit key generated by the Secure Enclave, and accessible only to the Secure Enclave, not any other hardware or software running on an iOS device. In the end, the only options are: bruteforcing passcodes on the original device while attempting to trick the device into allowing more than 10 failures, or prying open the Secure Enclave to obtain the Unique ID — both options a lot more complicated than just cloning the data and trying passcodes on it.

userbinator 9y ago
or prying open the Secure Enclave to obtain the Unique ID People have been cracking secure coprocessors of the type used in payment cards, TPMs, and the like for a long time, dare I say even those which were designed to a higher level of security than Apple's. The fact that there is an entire phone attached to it doesn't make much of a difference, but the technology behind this (FIB, microprobing, etc.) has been steadily dropping in price and increasing in availability for a long time.
- Scoundreller 9y ago
  > but the technology behind this (FIB, microprobing, etc.) has been steadily dropping in price Isn't it more of a cat and mouse? The defences also drop in price and increase in availability? As usual, old tech is becomes vulnerable. Hopefully most people will get the chance to upgrade to the latest and greatest before attacks get too easy and destroy the old device. I wonder what Chris Tarnovsky is up to these days...
- Godel_unicode 9y ago
  Fwiw, Apple has a $100k bounty on this type of exploit (pulling secrets from the secure enclave).
  - anilgulecha 9y ago
    I'm sure companies, like the one in the article, will pay substantially more for them.
  - OkGoDoIt 9y ago
    But Cellebrite apparently makes millions off of its service, so the economic incentives are still on their side.
    - movedx 9y ago
      I understand what you're saying here: why share the fact they've broken the SE for $100k when they can keep making millions. But if they cracked the SE, and kept that fact to themselves, they would be making even more money because every government on the planet would be coming to them. This is provided they kept it to themselves. It would mean a significant spike in the number of phones being cracked and people being arrested/charged/hung/etc. This would be a statistic that would jump off the charts and trigger Apple to essentially develop a solution straight away. The only way this would work is if they had cracked the SE and are doing an Enigma: keeping it top secret and only cracking very high profile targets with the technology, which I guess is possible.
      - userbinator 9y ago
        keeping it top secret and only cracking very high profile targets with the technology Of course. The "big guns" are not to be used lightly, as the saying goes.
      - majewsky 9y ago
        > This would be a statistic that would jump off the charts and trigger Apple to essentially develop a solution straight away. How, though? If the only information Apple has is that their SE scheme is broken, how is that supposed to help them develop a solution?
gruez 9y ago
I think he got the the idea right. Yes, you need the secret key burned into the CPU to decrypt anything, and yes, you can't easily extract the keys. but his claim is that by fully restoring the flash storage (presumably where the retry counter is stored), it's possible to bypass the "erase data after 10 failed attempts" policy by constantly resetting the counter back to its original state. It might take a while (you might have to go through the boot process each time, but for a 6 digit pin and 30 seconds each attempt, it's still less than a year.
- giovannibajo1 9y ago
  That doesn’t work as well because the counter is kept in the Secure Enclave so it’s not part of the flash contents. Also the exponential delay in attempts is enforced by the enclave. Previous iOS versions used to have some small window where you could race and power off after trying a passcode but before the enclave had incremented the counter, but that bug was fixed long ago. Maybe there are others unknown bugs of similar kind
  - gruez 9y ago
    >That doesn’t work as well because the counter is kept in the Secure Enclave so it’s not part of the flash contents I skimmed the secure enclave documentation at https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf (page 5, 14, 15), and I can't find anything to confirm that.
    - Scoundreller 9y ago
      It makes the most sense that it's in the Secure Enclave. Once you have control of the counter, you can run through the passphrase space in no time.
      - tinus_hn 9y ago
        Only if the pass’phrase’ is a short numeric code. iOS also allows a normal password.
greggarious 9y ago
>In the end, the only options are: bruteforcing passcodes on the original device while attempting to trick the device into allowing more than 10 failures, or prying open the Secure Enclave to obtain the Unique ID — both options a lot more complicated than just cloning the data and trying passcodes on it. If I'm understanding correctly, obtaining the unique ID would simply mean the strength of the AES key becomes the point of failure? (So a strong password means FBI doesn't get in)
- rphlx 9y ago
  You will still be trusting Apple to securely use your entire password rather than always truncating it to, say, 3 characters, and/or "backing up" some or all of it to their cloud - things that are rather difficult to independently verify.
jwbensley 9y ago
Is there no chance that Apple and/or the FBI have the list of phone serial numbers and matching AES key? (If that sounds sarcastic it's not meant to, genuine question as I don't know much a about this stuff!).
- tinus_hn 9y ago
  The key that is mentioned is only part of what you need to decrypt the data. The point of the secret key is to prevent an offline attack; you need to get the device to combine passwords or codes with the secret key to get the encryption key. That way the device can enforce speed nd maximum number of attempts.
BillinghamJ 9y ago
That’s not quite what the person above said. They said that the data would be pulled off the phone - in its encrypted form - then restored to make the phone forget the number of attempts. I think the Secure Enclave has independent built-in mechanisms for keeping track of the number of times things have happened though.
imaginenore 9y ago
> because the data is not encrypted by your passcode You enter the correct code, your data gets decrypted. So your 256-bit key is derived from a 4-6 digit number somehow, which reduces your search space to that 4-6 digit number space. Not sure how FaceID works, but that's probably even easier to break, people have done it with masks.
ensignavenger 9y ago
How does the Secure Enclave store all of those AES keys? I am guessing that the keys aren't random and are regenerated in order to do decryption, so "all" an attacker needs to do is break the key generation process, not the keys themselves.

userbinator 9y ago

or prying open the Secure Enclave to obtain the Unique ID People have been cracking secure coprocessors of the type used in payment cards, TPMs, and the like for a long time, dare I say even those which were designed to a higher level of security than Apple's. The fact that there is an entire phone attached to it doesn't make much of a difference, but the technology behind this (FIB, microprobing, etc.) has been steadily dropping in price and increasing in availability for a long time.

Scoundreller 9y ago
> but the technology behind this (FIB, microprobing, etc.) has been steadily dropping in price Isn't it more of a cat and mouse? The defences also drop in price and increase in availability? As usual, old tech is becomes vulnerable. Hopefully most people will get the chance to upgrade to the latest and greatest before attacks get too easy and destroy the old device. I wonder what Chris Tarnovsky is up to these days...
Godel_unicode 9y ago
Fwiw, Apple has a $100k bounty on this type of exploit (pulling secrets from the secure enclave).
- anilgulecha 9y ago
  I'm sure companies, like the one in the article, will pay substantially more for them.
- OkGoDoIt 9y ago
  But Cellebrite apparently makes millions off of its service, so the economic incentives are still on their side.
  - movedx 9y ago
    I understand what you're saying here: why share the fact they've broken the SE for $100k when they can keep making millions. But if they cracked the SE, and kept that fact to themselves, they would be making even more money because every government on the planet would be coming to them. This is provided they kept it to themselves. It would mean a significant spike in the number of phones being cracked and people being arrested/charged/hung/etc. This would be a statistic that would jump off the charts and trigger Apple to essentially develop a solution straight away. The only way this would work is if they had cracked the SE and are doing an Enigma: keeping it top secret and only cracking very high profile targets with the technology, which I guess is possible.
    - userbinator 9y ago
      keeping it top secret and only cracking very high profile targets with the technology Of course. The "big guns" are not to be used lightly, as the saying goes.
    - majewsky 9y ago
      > This would be a statistic that would jump off the charts and trigger Apple to essentially develop a solution straight away. How, though? If the only information Apple has is that their SE scheme is broken, how is that supposed to help them develop a solution?

gruez 9y ago

I think he got the the idea right. Yes, you need the secret key burned into the CPU to decrypt anything, and yes, you can't easily extract the keys. but his claim is that by fully restoring the flash storage (presumably where the retry counter is stored), it's possible to bypass the "erase data after 10 failed attempts" policy by constantly resetting the counter back to its original state. It might take a while (you might have to go through the boot process each time, but for a 6 digit pin and 30 seconds each attempt, it's still less than a year.

giovannibajo1 9y ago
That doesn’t work as well because the counter is kept in the Secure Enclave so it’s not part of the flash contents. Also the exponential delay in attempts is enforced by the enclave. Previous iOS versions used to have some small window where you could race and power off after trying a passcode but before the enclave had incremented the counter, but that bug was fixed long ago. Maybe there are others unknown bugs of similar kind
- gruez 9y ago
  >That doesn’t work as well because the counter is kept in the Secure Enclave so it’s not part of the flash contents I skimmed the secure enclave documentation at https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf (page 5, 14, 15), and I can't find anything to confirm that.
  - Scoundreller 9y ago
    It makes the most sense that it's in the Secure Enclave. Once you have control of the counter, you can run through the passphrase space in no time.
    - tinus_hn 9y ago
      Only if the pass’phrase’ is a short numeric code. iOS also allows a normal password.

greggarious 9y ago

>In the end, the only options are: bruteforcing passcodes on the original device while attempting to trick the device into allowing more than 10 failures, or prying open the Secure Enclave to obtain the Unique ID — both options a lot more complicated than just cloning the data and trying passcodes on it. If I'm understanding correctly, obtaining the unique ID would simply mean the strength of the AES key becomes the point of failure? (So a strong password means FBI doesn't get in)

rphlx 9y ago
You will still be trusting Apple to securely use your entire password rather than always truncating it to, say, 3 characters, and/or "backing up" some or all of it to their cloud - things that are rather difficult to independently verify.

jwbensley 9y ago

Is there no chance that Apple and/or the FBI have the list of phone serial numbers and matching AES key? (If that sounds sarcastic it's not meant to, genuine question as I don't know much a about this stuff!).

tinus_hn 9y ago
The key that is mentioned is only part of what you need to decrypt the data. The point of the secret key is to prevent an offline attack; you need to get the device to combine passwords or codes with the secret key to get the encryption key. That way the device can enforce speed nd maximum number of attempts.

BillinghamJ 9y ago

That’s not quite what the person above said. They said that the data would be pulled off the phone - in its encrypted form - then restored to make the phone forget the number of attempts. I think the Secure Enclave has independent built-in mechanisms for keeping track of the number of times things have happened though.

imaginenore 9y ago

> because the data is not encrypted by your passcode You enter the correct code, your data gets decrypted. So your 256-bit key is derived from a 4-6 digit number somehow, which reduces your search space to that 4-6 digit number space. Not sure how FaceID works, but that's probably even easier to break, people have done it with masks.

ensignavenger 9y ago

How does the Secure Enclave store all of those AES keys? I am guessing that the keys aren't random and are regenerated in order to do decryption, so "all" an attacker needs to do is break the key generation process, not the keys themselves.