Linear complementary dual code improvement to strengthen encoded circuit against hardware Trojan horses

Hardware Trojan Horses (HTH) are a serious threat to semiconductor industry with significant economic impact. We introduced in [10] a method called “encoded circuit”, which both prevents and detects HTH. We achieved this goal using Linear Complementary Dual (LCD) codes. In this paper, we achieve a lower overhead and a better tunability by using a Linear Complementary Pair (LCP) of codes, which are not necessarily dual. LCP have two security parameters d_Trigger and d_Payload, such that the knowledge of strictly less than d_Trigger bits of the encoded state reveals no information about the actual state; in addition, any HTH which modifies strictly less than d_Payload bits of encoded state, will produce an invalid codeword. The application on an 8-bit processor shows the improvement of the new LCP codes. We also show that it is possible to fully automate CAD flow to generate encoded circuits with LCP codes. Finally we encode a SIMON cryptographic co-processor and test its resistance against physical attacks like Side-Channel Analysis (SCA) and Fault Injection Analysis (FIA).