Secure Bootloader For Arm Microcontrollers

Abstract

Embedded systems are single purpose devices, where software updates are often omitted or very limited in comparison with personal computer systems. Such systems are typically using microcontrollers with limited memory and computing power. Enabling software updates on an embedded system brings some security issues that need to be taken into account. As soon as there is a possibility of software update, the device is exposed to risk of malicious or not original applications being executed on the device. In this paper a reference implementation of bootloader with security features is described. As a result of using asymmetric cryptography, the memory footprint and startup time is increased significantly. The contribution of this work is in finding the right algorithm that will offer trade-off between level of security and used resources of targeted microcontroller.