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jarkko

Jarkko Sakkinen

Just looking at what #Ubuntu installation stores #NVRAM of #TPM chip when installed with #TPM2 sealed #encrypted boot:

$ sudo tpm2_getcap handles-persistent
- 0x81000001
- 0x81010001

So: I guess the 2nd key, which has a policy bind, is what is “the fast path” with #PCR unsealing, and the first key is “the slow path” unsealed with the value given by snap recovery --show-keys.

Is this how it is laid out?

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jarkko

Jarkko Sakkinen

Reply to @jarkko
What puzzles me here is that 0x81010001 is reserved handle by TCG for the endorsement key so why would Ubuntu ever pick that as the NV index?

I'm confused but I barely skimmed the tpm2 tools outputs (tpm2_readpublic etc.).

For any Linux distribution builders out there, please read carefully before making any non-compliant changes: https://trustedcomputinggroup.org/resource/tcg-tpm-v2-0-provisioning-guidance/

That said I did not investigate this yet properly so forgive me I missed something essential :-)

This is way way too whitepaper'ish and lacks all the details: https://ubuntu.com/blog/tpm-backed-full-disk-encryption-is-coming-to-ubuntu
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