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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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Question About TPM Autodecrypt (mander.xyz)

submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/[email protected]

19 comments fedilink hide all child comments

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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[–] [email protected] 2 points 1 year ago* (last edited 1 year ago) (1 children)

I was wondering what security does the TPM password provides. If I understand correctly, it will prevent attacker from getting the data on the disk.

However, theoretically, attacker can boot the laptop and disconnect the disk to get a decrypted disk. Realistically, I think my laptop will shutdown when the chasis is opened (unless configured otherwise in the bios). So it should be safe?

[–] [email protected] 6 points 1 year ago (1 children)

However, theoretically, attacker can boot the laptop and disconnect the disk to get a decrypted disk.

This is not how this works. The bits are never decrypted on your disk / partition. If that was the case, a power loss would leave your device decrypted as well, and that is something a potential attacker might have control over.

What actually happens is that encrypted data is read from disk by the CPU, decrypted by the CPU and then written to RAM unencrypted. Unencrypted data should NEVER be written to non-volatile memory (the necessary exceptions, like the boot image, apply).

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago) (1 children)

Oh! That makes much more sense! Thanks!

Then I guess there is not much point in encrypting both the full disk and the home dir together then (if I trust gnome login screen cannot be by-passed), since the data is always encrypted when they are on the disk.

[–] [email protected] 3 points 1 year ago

In a single user context where the only user is also the administrator, full disk encryption has no disadvantages to home directory encryption AFAIK.