IP core protection using voltage-controlled side-channel receivers

This paper presents a new method for protecting netlist-based Intellectual Property (IP) cores in FPGAs by actively using voltage-controlled side-channel receivers. The receivers are realized by modulating the supply voltage of the chip, while at the same time detecting these changes from within the chip using a ring oscillator. The levels of the supply voltage can be determined by constantly monitoring the frequency of the ring oscillator. To prove authorship of an IP core, the verifier authenticates himself to the core over the voltage side-channel and sends commands that limit the core's functionality. By monitoring the regular outputs of the overall system, it is possible to detect illegitimately used cores after repeatedly turning them on and off. The working principle of our method is demonstrated by a case study, in which we protect several IP cores and place them on a Spartan 3 FPGA, and show the steps necessary for successful proof of ownership verification.