Taking into account indirect jumps or calls in continuous control-flow checking

Control-flow checking (CFC) is one of the main approaches to monitor the behavior of a microprocessor-based system without specific assumptions on error models (e.g., single bit flips). Many approaches have been proposed and evaluated, but none takes explicitly into account the possibility of indirect jumps or calls for which destination addresses are not hard-coded. This paper discusses first the need for an approach taking care of such sequence breaks. Then an approach is proposed to enhance current control-flow checking schemes.

I. Introduction

Soft errors, i.e. erroneous bits occurring without hardware defect, have become a significant concern for digital designers in many application domains of embedded market. Such errors can be caused by natural phenomena such as particle impacts [1] but also by malicious attacks using for example lasers [2]. In the first case, impacted applications include space and avionics but also more and more applications at ground level such as automotive or critical process control. The second case concerns circuits with security-related features, using secret data such as encryption keys. Coping with soft errors is therefore a major constraint to improve safety, availability and also security.