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Comment by gruez | Hacker News Reader

>To solve this, Android/iOS make an extremely long salt, so that + your PIN is your passphrase. In addition, there is logic to deter brute force attacks (e.g. after 10 guesses wipe my device)

nitpick: it's not just a "long salt", the "salt" is burned into the phone's security processor (trustzone or secure enclave) and can't be extracted so any attempts must be made using the exact phone. Using a gpu cracking cluster wouldn't help, for instance. AFAIK the anti-guessing logic is also implemented like this, otherwise you can just extract the salt and make unlimited attempts since the phone can't keep track of how many attempts you made.

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Trustzones or secure enclaves can be "broken" via uncapping. They are designed to be resistant to that, not unbreakable. Uncapping is not new and has been around for a long time, it just takes a lot of expensive hardware and expertise. Ultimately, the keys are bits on silicon, and with some acid, a scanning tunneling electron microscope, and a lot of time, the keys can be pulled off.

There are even articles from 2016 on how this is possible: https://arstechnica.com/information-technology/2016/02/how-t...

It is very unlikely this sort of technique would be used against anyone but the most extreme threat actors (potential terrorists, etc). But with physical access, all bets are off. It isn't a matter of if they can decrypt, but how long it will take them given the resources available.

Are you referring to chips like the Titan M in this as well?

Does the Titan M not store data in some physical medium? As far as I know, there isn't any way to prevent a truly dedicated and resourceful attacker from reading data that exists physically. The only constraints are money and time. A chip that e.g. self-destructed on detecting signs of tamper would be harder to break, but if the data exists physically, it must be recoverable in some way, no?

Bingo! Money and time. When you're going against an adversary with massive amounts of both, all bets are off. Physical access means eventual compromise.

Shouldn't a strong symmetric encryption with a long key prove to be safe enough as to not be crackable in a reasonable amount of time (~10 years), even if the hardware is directly accessible ?

I don't know why you were voted dead for asking a question. I vouched for your comment.

I don't know why you were voted dead for asking a question.

That's a new account (name in green). I think they start out dead. I think one or more comments need to be voted up and then the account becomes not dead (alive?).

Yes, but long keys are unwieldy. There's a comment I made in this thread[1] that calculates how long of a password you need for 128 bits of entropy.

[1] https://news.ycombinator.com/item?id=25358206

Probably, at least in practice if no critical components in the chain fail due to bugs/exploits and are as secure as intended (excluding the metaphorical "hammer VS fingers" attack).

I think the difference here between you and the poster you replied to is that you're probably correct given certain assumptions but the earlier post also remains correct in a conceptual or theoretical sense, like pure information/security theory

The trick for this case is a very long key, 1mb of more, try to recover all of them, you can lose about 60 bits, but not much more. What is the speed of extraction? You only need to delay it for a couple of decades.

Yeah some higher end security chips have passive mechanisms that make the microstructures more delicate and harder to reach and therefore harder to physically read. This is on top of active mechanisms that try constrain operation to well defined range of temperatures, voltage and power conditions to prevent brown out and booby traps that trigger effacement.

You have to disclose a lot of info during the cert process though so I don't think this is too much of a hurdle for big players like the NSA.

Newer devices (only Pixel 3 and newer, and Galaxy Note 20 and newer) also come with hardware security modules called Strongboxes (like Apple's Security Enclave).

https://www.android-device-security.org/client/datatable?sor...

> Trustzones or secure enclaves can be "broken" via uncapping.

That's true, but it's a big step up from the “push a button, data appears,” described in them article.

If you become "a person of interest" to MOSSAD, good luck. You'll be needing those magical amulets and the submarine to hide in - and YOU'RE STILL GONNA BE MOSSAD'ED UPON!

https://www.usenix.org/system/files/1401_08-12_mickens.pdf

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