Obfuscation of Digital Systems using Isomorphic Cells and Split Fabrication

Abstract

Due to the difficulty for design houses to have their own foundries due to costs and com- plexity, most design houses tend to outsource the production of their chips to third-party foundries. This could lead to piracy, the insertion of hardware trojans, unauthorized pro- duction and usage of chips, as well as other undesired side effects in case the foundries are untrustworthy. It is, therefore, necessary to protect designs against such malicious attempts, while maintaining the design secrets of third-party foundries. In this study, we reuse the concepts of split fabrication and isomorphic cells to introduce an algorithm for protecting hardware designs against malicious attacks at foundries. Split fabrication aims at splitting designs into two or more different parts that could be designed separately. One of the parts is relatively simple, and could be implemented by a relatively less advanced foundry, which needs to be trusted, and the other part contains the main functionality and usually needs to be implemented by an advanced foundry that is not necessarily trusted. We combine split fabrication with isomorphic cells, which are generic logic cells that could implement any functionality based on their connections. Split fabrication is applied by disconnecting some vital wires that define the functionality of isomorphic cells, and these connections could be connected later by a trusted foundry. Experimental results show improvements in security based on several concepts and met- rics we introduce in this thesis, and based on other concepts we reuse from recent related work.