Design of Asynchronous Polymorphic Logic Gates for Hardware Security

Polymorphic circuits are circuits that perform two or more different functions under varying operating conditions. This paper presents dual-function asynchronous polymorphic logic gates with functionalities selected by a change in supply voltage. Unlike previous polymorphic gates generated using an evolutionary approach for use in synchronous circuits, these asynchronous polymorphic gates are designed with a deliberate methodology that has been applied across multiple process nodes and verified in silicon using the TSMC 65nm process. The asynchronous polymorphic gates were designed to achieve aspects of "hidden" reconfigurability without the typical area and security drawbacks of field-programmable gate array (FPGA) hardware implementations.