Physical Design of FPGA Interconnect to Prevent Information Leakage

In this article we discuss dual/multi-rail routing techniques in an island style FPGA for robustness against side-channel attacks. We present a technique to achieve dual-rail routing balanced in both timing and power consumption with the traditional subset switchbox. Secondly, we propose two switchboxes (namely: Twist-on-Turn & Twist-Always) to route every dual/multi-rail signal in twisted pairs, which can deter electromagnetic attacks. These novel switchboxes can also be balanced in power consumption albeit with some added cost. We present a layout with pre-placed switches and pre-routed balanced wires and extraction statistics about the expected balance. As conclusion, we discuss various overheads associated with these techniques and possible improvements.