The Secure Boot feature (https://github.com/f-secure-foundry/usbarmory/wiki/Secure-boot-(Mk-II) https://github.com/f-secure-foundry/usbarmory/wiki/Secure-bo...)

The Secure Boot feature (https://github.com/f-secure-foundry/usbarmory/wiki/Secure-boot-(Mk-II) https://github.com/f-secure-foundry/usbarmory/wiki/Secure-bo...) in concert with full disk encryption prevent anyone from extracting keys. When used in combination with user supplied passphrases this leaves little chance for physical attacks. The two external security elements have active protection against glitching and side channel.