Design Protection Using Logic Encryption and Scan-Chain Obfuscation Techniques

Abstract

Due to increase in threats posed by offshore foundries, the companies outsourcing IPs are forced to protect their designs from the threats posed by the foundries. Few of the threats are IP piracy, counterfeiting and reverse engineering. To overcome these, logic encryption has been observed to be a leading countermeasure against the threats faced. It introduces extra gates in the design, known as key gates which hide the functionality of the design unless correct keys are fed to them.  The scan tests are used by various designs to observe the fault coverage. These scan chains can become vulnerable to side-channel attacks. The potential solution for protection of this vulnerability is obfuscation of the scan output of the scan chain. This involves shuffling the working of the cells in the scan chain when incorrect test key is fed. In this paper, we propose a method to overcome the threats posed to scan design as well as the logic circuit. The efficiency of the secured design is verified on ISCAS’89 circuits and the results prove the security of the proposed method against the threats posed.