this post was submitted on 06 Nov 2023
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Opal drives are self-encrypting, so they're done by the disk's own controller transparently. The main advantage is that there's almost no performance overhead because the encryption is fully hardware backed. The second advantage is that the encryption is transparent to the OS - so you could have a multi-boot OS setup (Windows and FreeBSD etc) all on the same encrypted drive, so there's no need to bother with Bitlocker, Veracrypt etc to secure your other OSes. This also means you no longer have a the bootloader limitation of not being able to boot from an encrypted boot partition, like in the case of certain filesystems. And because your entire disk is encrypted (including the ESP), it's more secure.
Thank you very much for your explanation.
I still feel skeptical about using a chips controller for encryption. AFAIK there have been multiple problems in the past:
Do you provide a password and there are 'hooks' which the boot process uses for you to enter the password on boot?
I think it is nice to have full disk encryption, but usually we are speaking about evil-maid attacks (?), and IMHO it is mostly game over when an attacker has physical access to your device.
Yes, I do provide a password on boot, as you said, keys can be extracted from the hardware so that's not secure, which is why I don't use the TPM to store the keys.
There are no hooks necessary in the bootloader, as it's the BIOS which prompts you for the password and unlocks the drive.
And yes, there have been implementation problems in the past, but that's why the Opal 2.0 standard exists - don't just buy any random self-encrypting drive, do your research on past vulnerabilities for that manufacturer, and check if there are any firmware updates for the drive (don't just rely on LVFS).
Also, the common hardware attacks rely on either a SATA interface (to unplug the drive while it still has power) or older external ports vulnerable to DMA attacks such as PCMCIA or Thunderbolt 3.x or below; so those attacks only affects older laptops. Of course, someone could theoretically install a hardware keylogger or something, but this is also why you have chassis intrusion detection, and why you should secure and check any external ports and peripherals connected to your machine. Overall physical security is just as important these days.
But ultimately, as always, it comes down to your personal threat model and inconvenience tolerance levels. In my case, I think the measures I've taken are reasonably secure, but mostly, I've chosen Opal for performance and convenience reasons.
Thank you very much for elaborating. :-)