[aauchter]

Would it be possible to build devices that could be unlocked a fixed number of times across all units (say 1,000 times). Devices could be heavily hardware encrypted, but unlockable with an encryption key, a portion of which comes from a publicly monitored blockchain/distributed ledger, that when used reduces the number of future uses.

This way, the government could be granted access for extreme cases, but without the potential for abuse or mass surveillance. Once there were 1,000 check-ins, not more keys could be generated.

Thoughts?

[acqq]

It's irrelevant, since the goal of FBI now is to make a precedent in being able to demand the changes in hardware or software based on the "All Writs Act" which should otherwise be the wrong act to allow them to effectively introduce infinite "Clipper chip" equivalents the way they haven't succeeded through the regular legislation procedures up to now.

Up to now such changes had to pass through the Congress, the laws had to be voted to solve such issues. This time they just quoted the Act which really just says they "may issue all writs necessary or appropriate." (check: https://en.wikipedia.org/wiki/All_Writs_Act ) Almost like citing the Catch 22.

It sounds too trivial but it's fundamentally dangerous in the powers they obtain if their current interpretation is accepted: the state doesn't have to make laws, the government can just write anything whenever it likes and say it's covered by "All Writs."

In the older cases when Apple cooperated Apple didn't have to change anything, neither their future hardware for retail nor the software of the hardware they produce for retail and the cases when nothing has to be changed but just the accessible data copied can be understood to be actually covered with the specific law, CALEA.

And don't forget how weak the argument of the FBI really is, the phone in question was a business phone of the terrorist, who actually intentionally destroyed his private phone before being chased. For this one he didn't care. Apple gave FBI the backup of the business phone, and was able to give them even the current state of it, but the government changed the backup password themselves. And the FBI can actually without Apple copy the data from the SSD disk of the phone and restore it any time to allow them more password tries. But they really want to make the precedent. Because they don't want that Apple produces the next phone on which FBI can't have more access.

[josinalvo]

Is it really technically feasible for the FBI to do a bit by bit copy of the SSD? Is there not some hardware restriction?

This seems highly relevant...

[acqq]

It is feasible but not purely with software, the SSD chip has to be desoldered from the circuit board, the socket inserted in the board and then the copying can be done as many times as needed and the combinations tried. There are companies that do exactly such kind of intervention.

https://www.aclu.org/blog/free-future/one-fbis-major-claims-...

[serge2k]

Not on the 5, apparently. My understanding is that it isn't the SSD but rather the flash on which the encryption key derived from user input is stored (the part you unlock with code and is wiped after 10 tries).

[acqq]

I don't agree. There were more texts claiming it can be done, they just have to try the combinations on the same circuit board, because one of the parts of the key is the part of the hardware, but the copying of encrypted data and then restoring from such backup can be done outside of the board, nothing is against that. Here's how Chinese trivially remove and replace the "solid state disk" chip.

http://9to5mac.com/2016/02/03/iphone-flash-storage-upgrade-s...

And the article that describes the process:

https://www.aclu.org/blog/free-future/one-fbis-major-claims-...

Yes it's just a chip that has to be copied, it's not a disk as we understand it in notebooks in a sense "a bunch of chips connected via SATA or M2" it's lower level but the principle is the same.

[ohazi]

No, you can't do this in a way that's as strong as conventional encryption. It would be too easy to present your system with an older view of the "ledger" to compel it to reveal expired/locked information. If your system were to mutate some encrypted internal state to keep track of the read count, this could be worked around via backups.

The only way your system could work is if it relied on some sort of TPM, which is essentially security by obscurity.

[alain94040]

Doesn't the blockchain offer some solution to that problem?

[yoha]

No. The blockchain is only a consensus through a network.

Anyone can make a tiny isolated network and create a fork that will look real to the target (here, the iPhone).

This is remotely related to the CAP Theorem [1]. Namely, you expect a blockchain not to fulfill the consistency requirement.

[1] https://en.wikipedia.org/wiki/CAP_theorem