BACKGROUND

Embedded systems are becoming more and more connected over time and have become one of a multitude of devices in the “Internet of Things”. Some of these devices, such as measuring instruments or smart meters, gain immense value by having a high level of connectivity. These devices must also be highly secure and trusted to produce accurate and essentially-incorruptible results. Practically speaking, the parties being affected by the measuring instrument cannot check the results and, hence, they must be able to rely on its accuracy at a very-high level.

One solution is to separate legally relevant and legally non-relevant data and operate a device that has two micro-controllers. One of the micro-controllers is dedicated to the legally relevant functionality and one of the micro-controllers is dedicated to the legally non-relevant functionality. This allows at least the portion of the device running the legally relevant system to be secure and safe from tampering. Typically, the legally relevant portion of the system cannot be upgraded while the legally non-relevant portion allows for remote firmware upgrades. This is a less than optimal solution. Multiple micro-controllers require more PCB space, consume more power, and offer less flexibility.

It would be desirable for a system that has 1) a single micro-controller that is capable of handling both legally relevant and legally-non relevant applications; and 2) has the inherent security and trustworthiness while also being expandable to adapt to the ever changing needs of the “Internet of Things”.

SUMMARY

One implementation is for a device. The device includes a controller having a memory protection unit, a legally relevant memory portion capable of interacting with the controller, a legally non-relevant memory portion capable of interacting with the controller, an interface in the memory protection unit that allows a privileged application to access the legally relevant memory portion and disallows an unprivileged application to access to the legally relevant portion, and an interrupt system, wherein when the unprivileged application makes an attempt to interact with the legally relevant memory portion, the memory protection unit takes an action associated with the unprivileged application.

Another implementation includes one or more hardware-based non-transitory memory devices storing computer-readable instructions which, when executed by the one or more processors disposed in a computing device, cause the computing device to enable an interaction between a controller and a legally relevant portion using a memory protection unit, enable an interaction between the controller and a legally non-relevant portion using the memory protection unit, allow a privileged application to access the legally relevant portion, receive an attempt from the unprivileged application to access the legally relevant portion, and perform at least one action with respect to the unprivileged application.

Another implementation is for a method for protecting a device. The method includes enabling an interaction between a controller and a legally relevant portion using a memory protection unit, enabling an interaction between the controller and a legally non-relevant portion using the memory protection unit, allowing a privileged application to access the legally relevant portion, receiving an interrupt from an unprivileged application configured to interact with the legally relevant portion, and performing an operating system level response to the interrupt.

