Problem: Currently have no way to verify integrity of my offline encrypted system. I would like to ensure the system hasn't been physically tampered with while I've been away from it.
(To clarify:while I am aware that the system cannot be modified without gaining access to the my encryption key. This question is to address the off-chance that the encryption is somehow bypassed. i.e. They gain access to my encryption key.)
Proposed solution: Hash the contents of the hard drive and have that hash added to a thumbdrive that I will maintain control of.
How difficult would it be to obtain a hash for a harddrive before every system shutdown and have that hash added to a log on a thumbdrive that can be validated after every login?
Would I need to have the system unmounted to ensure this method is valid?
Is there already a prepackaged solution that you are aware of for this problem?
I would need to ensure physical security of the thumbdrive to make sure the checksums match is valid (maintaining physical security of a keydrive is much easier than carrying a computer around with me)
This method would probably be more easily implemented on virtual machines (though that doesn't do anything if the host is compromised).
Having a Live Linux USB on the thumbdrive to create the hash on the unmounted drive may be a more simplistic method, although not quite as streamlined.
Other thoughts: I am aware that system encryption offers some level of integrity assurance. But in the off chance that encryption becomes violated, I would like to know.
OS: Arch Linux