Embedded Systems software reliability is increasingly important, therefore methods to harden existing software are needed. In general, hardening software against various failures is a necessity in modern computer systems. A lot of work has been published regarding many possible ways to achieve this non-functional requirement. Relevant topics include, e.g., test procedures, recommended development flows, and hardware measures like watchdog timers. One of these methods seems very promising to be software implemented in modern embedded systems: Control Flow Checking by signatures. Various authors have shown the effectiveness and feasibility of Control Flow Checking (CFC) by signatures for personal computer software. For instance it has been shown for standard computer-systems, that CFC is capable of reducing undetected control flow errors by at least one magnitude.
This survey will focus on the applicability of such software hardening methods to embedded systems, while adhering mainly to software based approaches. Published methods will be summarized and compared. Furthermore methods to simplify derived control-flow graphs to essential states will be emphasized. Finally the possibility to apply run-time verification to the Control-flow Checking Software is considered.
