Hi everyone, I found the great question on booting encrypted drives, and since I’m somewhat paranoid I’d like to ask a follow-up:

When the key to decrypt the drive is input into the system, I’m assuming it stays in the RAM till the time the computer shuts downs. We know that one could, in theory, get a dump of the contents of the RAM in such a state, if done correctly. How would you deal with this problem? Is there some way to insert the USB, decrypt the drive, and then remove the USB and all traces of the key from the system?

Thanks!

Edit: link to the question I referenced: https://feddit.de/post/6735667

  • mumblerfish@lemmy.worldEnglish
    4·
    9 months ago

    The key needs to be available to continue to be able to decrypt the data on the device. All encrypted data is not decrypted as you mount or unlock your encrypted device, that is done one the fly as you use it.

    The attack you are thinking of should also not be relevant. What you worry about appears to imply that you are more concerned about the key being protected, rather than the data the key protects. You seem to wish to have your decrypted data available, but not the key.

    • MigratingtoLemmy@lemmy.worldOPEnglish
      2·
      9 months ago

      Thank you, I realise that what I’m asking for might not be physically possible. I’m certain that RAM loses all of its contents after a loss of power, but would it be possible to pad the RAM before/during the shutdown process to make sure that nobody gets to the key?

      • aard@kyu.deEnglish
        4·
        9 months ago

        Yes, but: somebody trying to attack your machine that way would cut the power and try to freeze your memory modules. So that mitigation wouldn’t trigger.

        If you think you really need to guard against that attack you’d have to look into physical security: At room temperature there’s a pretty short window available for saving the contents. So if you manage to remove access of possibly used cooling agents to the memory modules you already made things quite tricky.

        Now if you can make removing the memory modules hard as well, and prevent booting anything but what you want to be booted there’s a decent chance it’ll be impossible to recover memory contents.

        If that still isn’t good enough you’d have to look into providing a means of physical destruction of the memory modules triggered by a backup power source inside the case on unexpected power loss.