Mandos works with initramfs images created by both initramfs-tools and dracut, and is present in Debian since 2011, so no need to use a third-party package.
Mandos is also for Debian (and all Debian-based systems), and not Red Hat (although there is nothing preventing a port, since Mandos supports Dracut-created initramfs images).
Finally, Mandos was initially created in in 2007, many years before tang/clevis, and literally by a person in a dorm room, not by whatever academics/scientists who seem to have dreamed up the cryptography/protocol tangle that is tang/clevis. Mandos has changed some since then, from initially using broadcast UDP and X.509 certificates, to using DNSSD and raw public keys², but has otherwise remained very similar to its initial design.
I think FOSDEM had a talk a few years ago about that solution and their tang server. It is very similar in concept. They use McCallum-Relyea exchange, and we use PGP encryption, but the basics are the same in that you need information stored at the server and information stored in the unencrypted initramfs in order to be combined and turned into the encryption key. If my understanding of the McCallum-Relyea exchange is correct, they also combine the key creation and perfect forward security of the transaction into a single protocol, while we use TLS and client keys for the perfect forward security aspect and PGP for data at rest.
With tang you need to verify the hash of the tang server in order to prevent a MITM threat from extracting the server side part during the key creation process, while with Mandos you configure it manually with configuration files.
Tang uses REST and JSON. Mandos sends a single protocol number and then sends the data.
Outside of those design differences, there are some packaging aspects. Tang was designed for Redhat/Dracut, while Mandos was designed for Debian and initramfs-tools (Today Mandos also support Dracut, but it is not packaged for Redhat). Redhat packaging has been requested multiple times for Mandos, but neither of us two developer are Redhat users.
To add some historical context, I recall a Debconf BoF by the developers of initramfs-tools about if they were going to continue developing initramfs-tools or giving up and port everything to Dracut, and the silence was fairly deafening. People did not want to give up on initramfs-tools, but everyone recognized the massive duplication that those two project are. Similarly, the reason why Redhat had chosen initially to develop Dracut rather than just port initramfs-tools is also fairly big mystery, and is generally considered a Not Invented Here syndrome. Today there are however some distinct difference in design between the two systems.
1. SSH into the Pi
2. Issue the Wake-on-LAN packet to boot the server
3. Tunnel that server's SSH port to my laptop
4. SSH into the initramfs SSH server (I use TinySSH), enter the decryption key
5. Wait for server to come up, then access via Tailscale
This is more complicated than the author's setup in that it requires another device (the Pi), but it's simpler in that you don't need to have the initramfs on your Tailnet.
Other options that I've investigated that involve having a second server:
* A second server with Tang, and Clevis in the initramfs OS
* Keylime
Putting tailscale in the initramfs, and then updating the certs on a frequent enough schedule, seems risky to me. I've already played around with limine enough that I know I don't want to install much in the initramfs...
Realistically for a home server what you are worried about is someone breaking in and selling your drives on Facebook marketplace rather than the FBI raiding your nextcloud server. So TPM automated unlock is perfectly sufficient.
If someone steals the entire machine, the drives will unlock themselves automatically. I don't think it's worth the risk to assume a hypothetical thief is too lazy to check if there's any valuable data on the disks. At the very least, they'll probably check for crypto wallets.
With something like Clevis and Tang, you can set it up so it only auto unlocks while connected to your home network, or do something more complex as needed
I've done stuff with mkinitcpio / initramfs on arch before, can't remember exactly what for. I still run arch on my main laptop. I'm running nixos on my home server though, and adding something like this is so easy by comparison.
Just use dm-verity for remote servers.
If you have disk encryption, your data now requires the police to force you to produce a password, which may or may not be within their powers, depending on the jurisdiction.
It’s strictly better to have full disk encryption and remote unlocking than no disk encryption at all, because it prevents such „system was switched off by accident“ attacks.
Maybe I have a server at home, with a locked cabinet and vibration sensors, that houses a server or two and they all use full disk encryption, but I still want to be able to reboot them without having to connect a physical keyboard to them. So no one has physical access, not even me, but I still want to be able to reboot them.
Or countless of other scenarios where it could be useful to be able to remotely unlock FDE.
The argument was that physical access gives up the FDE key.
Or is there already a solution to this that I've been missing? (Yeah, KVM/IPMI/etc, I know, but not all hosters make it easy to get to that.)
Debian has (or had; at least my Devuan still has) a simple shell script as first init. Was an interesting read and helped me understand were to add my remote rootfs decryption.
https://salsa.debian.org/kernel-team/initramfs-tools/-/blob/...
The `base` hook installs the shell PID 1, the `systemd` hook installs systemd as PID1. The default hook setup was changed with the latest'ish release to default too the `systemd` hook setup.
Shell `init`; https://gitlab.archlinux.org/archlinux/mkinitcpio/mkinitcpio...
Give it a go: https://aur.archlinux.org/packages/mkinitcpio-wifi
I once built a demo-ish encrypted network boot system using similar initrd techniques. It's a fun hack working in the preboot environment.
It's not a huge problem but it certainly means some recovery scenarios would be painful.
I've only seen it on some paranoid-level devices in industry (typically devices handling biometric identity verification services).
IIRC this one is a Linux image that boots up, unlocks the normal Bitlocker partition via whatever mechanism you need, then hands control back to the Windows bootloader to continue onwards.
https://winmagic.com/en/products/full-disk-encryption-for-wi...