Implementation of Obfuscated Control Logic Circuit with LegUp and oLLVM
It is an important issue to protect the intellectual property of software. The authors proposed to conceal some part of software by implementing it as logic circuit. Though the security is further improved by obfuscating the logic circuit, it requires much effort to develop the dedicated obfuscation tool. Matsuoka et al. proposed using the software obfuscation tool, Obfuscator-LLVM (oLLVM), with C-backend (CBE) and Xilinx Vivado HLS (high-level synthesis) to generate the obfuscated logic circuit. This study proposes adopting another HLS, LegUp, to obfuscate logic circuit. The feasibility of these two methods are examined with 12 applications of CHStone benchmark, each of which were evaluated with four obfuscation methods (total 48 cases). In our experiments, Matsuoka’s method failed to generate the correct hardware in 5 cases out of 48 cases. Meanwhile, the proposed method successfully generated the correct hardware for all 48 cases. The average latency derived by the proposed method was 43% larger than that by Matsuoka’s method. The logic scale derived by the proposed method was also 42% larger (LUT) and 112% larger (FF) than that by Matsuoka’s method.