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it took me forever to believe a coworker who told me that keys just go across the bus to the TPM in plaintext "well, no, that can't be right, the whole bitlocker threat model is designed around an attacker with physical access, they wouldn't just" yup they totally do t.co/lyZ5pUGi5C

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@XMPPwocky

Jul 29, 2021

Frog put the keys in a TPM. "There", he said. "Now the disk is encrypted when the machine is off." "But we can turn the machine on and sniff the keys", said Toad. "That is true", said Frog.

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AOSP has a really nice approach to integrating secure elements for encryption: grapheneos.org/faq#encryption It takes output of scrypt key derivation runs it through a personalized hash specific to the secure element and uses it to authenticate to get back a token for key derivation.

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Titan M on Pixels is also paired with the TEE on the phone and the communication between the SoC and dedicated secure element is encrypted. TPMs are pretty bad as a whole. It's a legacy serial device with an awful API. Microsoft should really just make their own modern API...

10:30 PM · Jul 29, 2021Twitter Web App

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