—Hardware Intellectual Property (IP) cores have emerged as an integral part of modern System–on–Chip (SoC) designs. However, IP vendors are facing major challenges to protect hardware IPs and to prevent revenue loss due to IP piracy. In this paper, we propose a novel design methodology for hardware IP protection and authentication using netlist level authentication. The proposed methodology can be integrated in the SoC design and manufacturing flow to provide hardware protection to the IP vendors, the chip designer, and the system designer. Simulation results on ISCAS–89 benchmark circuits show that we can achieve high levels of security through a well– formulated obfuscation scheme at less than 10% area overhead under delay constraint.