PureBoot is Purism’s secured boot process which combines a number of technologies. Physically, PureBoot requires TPM enabled Librem laptop with proper coreboot version (actually, it is possible to setup this on a Librem laptop without TPM, as well), and a Librem Key, Purism’s USB security token.
With PureBoot you can easily verify if the your device software has been tampered with while you were not attending it, or during transit from Purism to you. Each time existing files in /boot change, Librem Key will warn you by flashing red light. This means that there may be some false positives if you upgrade your system, so you may want to check out best practices with PureBoot, compiled by our CSO.
PureBoot also allow you to unlock your encrypted disk using your Librem Key (having to enter just your Key’s PIN).
For more information and manuals please see PureBoot documentation.