This is an alternative to manually typing your password to decrypt your home server disks.
The idea is that you have a Tang server somewhere on your local network. When your server boots up, it needs to communicate with the Tang server to unlock the disk. Tang doesn’t store the key and is stateless, but the client requires Tang’s cooperation to compute the key.
For me, I’m thinking about someone breaking into my house and stealing my computer. Currently, I have LUKS read a keyfile from a USB drive… but I almost always leave it plugged in… so a thief would probably accidentally steal that too.
With this setup, I’m thinking maybe I could setup a Pi on the opposite side of my house, ideally hidden. And then if my home server gets stolen, LUKS wouldn’t be able to reach my Tang server, and therefore not unlock anything.
I used to use them, yes. It’s a pretty solid setup, especially like you say, if the tang server itself requires you enter a password to unlock.
A while ago I moved to tpm and secureboot to auto-unlock my servers on boot. It’s definitely slightly less secure, tpm vulnerabilities or a severe enough vulnerability in one of the network services on the machine and a hacker could get into them. But it’s quite a bit more secure than storing the unlock key on usb, and requires at least some degree of hacking skill to break in.
sbctl makes the process of signing boot files pretty easy, systems-cryptenroll for setting up tpm auto-unlock