It's supposed to be truly hardware-bound with a private key for at least one of the low-level primitives in hardware. That's what iPhones and other phones like Pixels claim to be the status quo already. An adversary can certainly extract that key from the hardware though.
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Replying to @CopperheadOS @peterktodd and
This isn't something that's intended to be inherently / theoretically secure against an attacker performing an offline brute force attack. The feature has succeeded if doing an offline brute force requires sending a device to a lab to perform an expensive extraction process.
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Replying to @CopperheadOS @peterktodd and
It's succeeding in this case. There's a widely available tool for cracking the encryption but it only performs an online brute force attack and apparently not even at the full throughput that the device is documented as being able to do key derivation.
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Replying to @CopperheadOS @spudowiar and
I'm not sure we're in any disagreement here... If anything, the fact that Apple's passcode strengthening isn't designed to withstand that attack makes it all the more important to understand what backup options you have if you need better security than that.
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Replying to @peterktodd @CopperheadOS and
That's precisely why I asked how many iterations the KDF was doing. It's also why I said elsewhere in the thread that Apple might have been smart to also do a parallel CPU/RAM-bound KDF while the secure hardware one was running.
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Replying to @peterktodd @CopperheadOS and
Apple’s entire security posture is based around catering to a vast majority of users who won’t use strong passcodes. Six digits isn’t going to be secure at any level of KDF complexity.
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Replying to @matthew_d_green @peterktodd and
For the rest of the world who *are* experts, maybe it’s just easier for those people to memorize strong 50-80 bit level passcodes.
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Replying to @matthew_d_green @peterktodd and
One of the major issues on a mobile device is that a strong passphrase is extremely inconvenient since it needs to be entered so often. Strong passphrase + fingerprint works as a compromise but fingerprint / face / iris unlock is a gaping hole before it times out.
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Replying to @CopperheadOS @matthew_d_green and
Don't just need to remember a strong passphrase but endlessly enter it over and over again which is a real pain especially without a real keyboard. It would be inconvenient even with a full size physical keyboard since devices lock so quickly (and for good reason).
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Replying to @CopperheadOS @matthew_d_green and
It's not just an inconvenience; it's a major security risk (shoulder surfing, etc.).
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Should only ask for strong pw for key derivation after manual secure-lock or any evidence of tampering/brute-force attempt. Detection of tampering should be 100% isolated from software control. Otherwise use user's preference of short pin or biometrics to unlock.
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