HLock+: A Robust and Low-Overhead Logic Locking at the High-Level Language

Abstract

With the emergence of the horizontal business model in the semiconductor industry, numerous hardware security concerns have been emerged, including intellectual property (IP) theft, malicious functionality insertion, and IC overproduction. To combat these threats, logic locking has been introduced as one of the most prominent countermeasures, and advances in logic locking have led the most recent techniques towards higher levels of abstractions, i.e. register transfer language (RTL) or highlevel languages (C/C++). In this paper, we propose HLock+, a robust logic locking framework at the high-level design language. HLock+ consists of two main parts to achieve multiple goals: (I) Locking in HLock+ is based on a formal analysis over design specifications, assets, and critical operations to determine locking points in the design to provide the best solution in terms of desired attack resiliency (e.g., SAT attacks), and locking key size; (II) We integrate the formal analysis with a point function locking technique, in which the locking candidates have been chosen by an optimization algorithm helping us to boost the efficiency of the approach with the given area, power, and performance constraints. Furthermore, the proposed framework ensures a dynamic/automatic locking solution based on a set of specifications, and it is well suited for large-scale designs. Apart from having lesser development/verification efforts, HLock+ at highlevel language will be followed by high-level synthesis (HLS) and RTL synthesis, which provides superior uniform distribution and optimum output corruptibility. We show that HLock+ provides potent robustness against de-obfuscation attacks, e.g. SAT and machine-learning-based attacks, while the overhead is kept low.