The Strange State of Authenticated Boot and Disk Encryption on Generic Linux Distributions

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2021-09-23 10:00:10

TL;DR: Linux has been supporting Full Disk Encryption (FDE) and technologies such as UEFI SecureBoot and TPMs for a long time. However, the way they are set up by most distributions is not as secure as they should be, and in some ways quite frankly weird. In fact, right now, your data is probably more secure if stored on current ChromeOS, Android, Windows or MacOS devices, than it is on typical Linux distributions.

Generic Linux distributions (i.e. Debian, Fedora, Ubuntu, …) adopted Full Disk Encryption (FDE) more than 15 years ago, with the LUKS/cryptsetup infrastructure. It was a big step forward to a more secure environment. Almost ten years ago the big distributions started adding UEFI SecureBoot to their boot process. Support for Trusted Platform Modules (TPMs) has been added to the distributions a long time ago as well — but even though many PCs/laptops these days have TPM chips on-board it's generally not used in the default setup of generic Linux distributions.

How these technologies currently fit together on generic Linux distributions doesn't really make too much sense to me — and falls short of what they could actually deliver. In this story I'd like to have a closer look at why I think that, and what I propose to do about it.