Hello ! I’m trying to protect myself from Cold boot attacks, and so wipe the rams on shutdown, to avoid any leaks.
related:
Wipe RAM of VMs synchronously when shut down and killed #1562
from above link:
marmarek commented on Sep 14, 2019
On memory balancing, the memory definitely is zeroed before returning it to Xen. On VM shutdown/crash/etc it is too, but I’m not sure if it’s done synchronously, or asynchronously - IOW at which point in time it is guaranteed to be cleared already.
also from last comment on the link:
https://forums.whonix.org/t/is-ram-wipe-possible-inside-whonix-cold-boot-attack-defense/5596
also related:
https://forum.qubes-os.org/t/anti-forensics/7052
https://forum.qubes-os.org/t/clear-cache-and-swap-after-dvm-shutdown/8241
I don’t think you can rely on shutdown to zero the memory, someone trying to do a cold boot attack wouldn’t shut down the system, they would hard reset the system.
You could look into memory encryption, I think it might be able to protect you against an attacker that has the ability to cold boot the system.