Using secure microcontrollers in IoT applications

Security in IoT devices is a major topic that IoT is facing. Rising awareness from the customer side and up-coming regulations will force manufacturers to increase the level of security on their IoT devices. Particularly, it is a challenge to leverage the elaborate, well-known computer security algorithms to resource-constrained IoT devices. For the Cortex-A processors Arm® has already introduced their security extension TrustZone® for quite a while. With the new generation of secure microcontrollers, Arm® TrustZone® is now available for battery-powered IoT devices. Furthermore, these secure microcontrollers provide additional security features, such as hardware accelerators for cryptographic operations, secure key storage, and sophisticated random number generators, therefore, increasing security on resource-constrained IoT devices. The paper introduces the concept of these new secure microcontrollers and provides an overview of their features, by showing an application example that covers the topics of secure boot and the usage of TrustZone®. Furthermore, the paper presents energy measurements of the implemented example comparing them to the execution on conventional microcontrollers without TrustZone®. Finally, the paper summarizes advantages and weaknesses of secure microcontrollers compared to dedicated off-chip solutions like secure elements