SCI-FI: Control Signal, Code, and Control Flow Integrity against Fault Injection Attacks

Fault injection attacks have become a serious threat against embedded systems. Recently, Laurent et al. have reported that some faults inside the microarchitecture escape all typical software fault models and so software counter-measures. Moreover, state-of-the-art counter-measures, hardware-only or with hardware support, do not consider the integrity of microarchitectural control signals that are the target of these faults. We present SCI-FI, a counter-measure for Control Signal, Code, and Control-Flow Integrity against Fault Injection attacks. SCI-FI combines the protection of pipeline control signals with a fine-grained code and control-flow integrity mechanism, and can additionally provide code authentication. We evaluate SCI-FI by extending a RISC-V core. The average hardware area overheads range from 6.5% to 23.8%, and the average code size and execution time increase by 25.4% and 17.5% respectively.