Introducing TFUE: The trusted foundry and untrusted employee model in IC supply chain security

In contrast to other studies in IC supply chain security where foundries are classified as either untrusted or trusted, a more realistic threat model is that the foundries are legally and economically obliged to perform trustworthy service, and it is the individual employees that introduce security risks. We call the above as the trusted foundry and untrusted employee (TFUE) model. Based on this model, we investigate new opportunities of establishing trustworthy operations in foundries made possible by double patterning lithography (DPL). DPL is used to setup two independent mask development lines which do not need to share any information. Under this setup, we consider the attack model where the untrusted employee(s) may try to insert Trojans into the circuit. As a countermeasure, we customize DPL to decompose the layout into two sub-layouts in such a way that each sub-layout individually expose minimum information to the untrusted employee.