Good point, I’ll add it on my TODO list

The decryption key is more than 20 random character, so if you get only half of it is not a biggie and it doesn’t look like anything interesting.

It is on the internet mostly because I don’t have anything else to host it locally. But I see some benefit: I wanted for the server to be available immediately after a power failure. If it fetches the key from internet I just need for the router to be online, if it fetches it from the local network I need another server running unencrypted disk.

Linux from chromebook is just a configuration you enable from the settings menu. If offers you a shell which is similar to a Ubuntu and you can install standard Linux software using the “apt install” command. Said so, if they cannot even install chrome extensions this is likely disabled too.

Second reason. It may run your vpn, with the server down you cannot connect to it and provide the decryption key unless you are connected to the same network.

There are some good answer around where the server can easily decrypt automatically as long as it is connected in your home but will likely fail at a thief’s home. These are a much safer setup than keeping data unencrypted even if they are not bullet proof.

The issue I see with TPM is that it will always unlock the drive as long as it is connected to the same motherboard. It means you have to trust all the services you run to be correctly secured. Like there is little reason to encrypt your hard drive in this way if later you have a samba share open without any password.

I’ve configured something similar. The /boot partition is the only unencrypted. In the initramfs there is a script that downloads half of the decryption key from http, while the other half is stored in the script itself. The script implements automated retry until it can fetch the key and decrypt the root partition.

My attack model here is that, as soon as I realize someone stole my NAS I can shutdown the server hosting half of the decryption key making my data safe. There is a window where the attacker could connect it to a network and decrypt the data, but it is made more difficult by the static network configuration: they should have a default gateway with the same IP address of mine.

On my TODO list I also have to implement some sort of notification to get an alert when the decryption key is fetched from internet.

They also says that installing a different os will invalidate the warranty. But their x86 models (I wasn’t aware of the arm) literally ship with a USB drive connected to an internal USB port which starts the setup of their custom Linux if it detects no OS on the internal drives. You just swap that pendrive and you install whatever you want. I cannot say it works for all the models, but I did a little research before buying mine and I can say it run debian for more that one year without any compatibility issue.

Terramaster is just a PC in a NAS form factor. You can install your favourite OS without any issue

I agree, but having a webui is nicer on android, so I installed https://www.filestash.app/ configured to use samba as backend so permissions and passwords are the same

there is a feature request with a lot of good comments on their forum. The summary of the last time I checked it was on the lines: “it is a reasonable request but it is terribly hard to implement it correctly and since we currently have no capacity to do it we prefer leaving it not implemented instead of offering any alternative which could give a false sense of security”

If you want to encrypt only the data partition you can use an approach like https://michael.stapelberg.ch/posts/2023-10-25-my-all-flash-zfs-network-storage-build/#encrypted-zfs to ulock it at boot.

TL;DR: store half of the decryption key on the computer and another half online and write a script that at boot fetches the second half and decrypt the drive. There is a timewindow where a thief could decrypt your data before you remove the key if they connect your computer to the network, but depending on your thread model can be acceptable. you can also decrypt the root portion with a similar approach but you need to store the script in the initramfs and it is not trivial.

Another option I’ve seen suggested is storing the decryption key on a USB pendrive and connect it with a long extension cord to the server. The assumption is that a thief would unplug all the cables before stealing your server.