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Question About TPM Autodecrypt (mander.xyz)
submitted 2 years ago* (last edited 2 years ago) by to c/linux@lemmy.ml
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I have setup my fedora to use LUKS encryoted partitions. But entering two passwords gets quite tiring, as I shutdown my laptop quite often to get the benefit of LUKS (I am assuming nothing is encrypted when in suspend, please correctme if I am wrong)

I am thinking about setting up TPM autodecrypt. However, I was wondering does the decryption happen on boot or after I login?

If it happens on boot, then it seems like the benefit is pretty limited compare to a unencrypted drive. Since the attacker can simply boot my laptop and get the unecrypted drive.

Am I missing something here? I was wondering is there a way for me to enter my password once and unlock everything, from disk to gnome keyring?

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[–] 5 points 2 years ago (1 child)

The data on disk doesn't get decrypted at any time. Even if they boot it, they would still need to log in somehow.

There are attacks through DMA or extracting the decryption key from RAM, but those are not going to happen by a casual laptop thief.

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  • [–] 3 points 2 years ago (1 child)

    ...or extracting the decryption key from RAM.

    Moral of the story:

    Always shutdown the computer when you are not using it, kids.

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  • [–] 7 points 2 years ago (1 child)

    I see your decryption key extraction and offer you a 5 dollar wrench.

    The wrench also comes with DMA (direct mechanical assault), RDMA (remote direct mechanical assault via throwing), and DDIO (deals damage if opposing) capabilities. It's a real NSA bargain!

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  • [–] 1 point 2 years ago (2 children)

    But if the key is fully wrench-safe inside the TPM. You do not know it, you can not get convinced to give it up -- even after repeated wrench use.

    Of course the recovery key that typically goes with it and you logging password is not wrench safe, so that does not protect the system fully, while getting you a matching set of broken kneecaps.

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  • [–] 2 points 2 years ago

    you don't know it, you can not get convinced to give it up

    It's ok that you don't know it, just log into your computer please and we'll take care of setting a new key. Or you can have a conversation with Mr Wrench again.

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