How Secure is Split Manufacturing in Preventing Hardware Trojan?

With the trend of outsourcing fabrication, split manufacturing is regarded as a promising way to both provide the high-end nodes in untrusted external foundries and protect the design from potential attackers. However, in this work, we show that split manufacturing is not inherently secure. A hardware trojan attacker can still discover necessary information with a simulated annealing based attack approach at the placement level. We further propose a defense approach by moving the insecure gates away from their easily-attacked candidate locations. Experimental results on benchmark circuits show the effectiveness of our proposed methods.