Verifying Software Integrity in Embedded Systems: A Side Channel Approach

In the last few decades embedded processors have invaded the modern lifestyle. Embedded systems have hardware and software components. Assuring the integrity of the software is very important as it is the component that controls what the hardware does through its instructions. Although there exist a number of software integrity verification techniques, they often fail to work in embedded environment. One main reason is, the memory read protection, frequently implemented in today’s microprocessors, that prevent the verifier from reading out the necessary software parts. In this paper we show that side channel leakage (power consumption) can be used to verify the integrity of the software component without prior knowledge of the software code. Our approach uses instruction-level power consumption templates to extract information about executed instructions by the processor. Then this information together with pre-computed signatures are used to verify the integrity of the executed application using RSA signature screening algorithm. The instruction-level templates are constructed ahead of time using few authentic reference processors.