An Improved Encoding Technique for Gate Level Information Flow Tracking

High-assurance systems, such as flight control and banking systems require strict guarantees on information flows or else face catastrophic consequences. Information flow tracking (IFT) is a frequently used security measure for preventing unintended information flows in such systems. Recently, Gate Level Information Flow Tracking (GLIFT) has been proposed to track information flows at the hardware level. GLIFT enables a concrete understanding of all information flows from Boolean gates. It unifies the notions of explicit flows, covert channels, and even timing channels at the gate level and provides a general approach for enhancing important security properties such as integrity and confidentiality. This article presents a new encoding scheme for GLIFT with fewer encoding states by combining two states into one. Unlike the previous method, this reduction in encoding states allows the GLIFT tracking logic to operate independently from the original circuit. This independence allows for the GLIFT logic to be configured as both redundancy and tracking logic for the original circuit. Further, experimental results show this new state assignment provides on average 25.7% reductions in area, 31.4% reductions in delay, and 48.6% decrease in simulation time for several IWLS benchmarks.