Distributed Logic Encryption: Essential Security Requirements and Low-Overhead Implementation

Due to outsource manufacturing, the semiconductor industry must deal with various hardware threats such as piracy and overproduction. To prevent illegal electronic products from functioning, the circuit can be encrypted using a protected key only known to the designer. However, an attacker can still decipher the secret key utilizing a functioning circuit bought from the market, and the encrypted layout leaked from an untrusted foundry. In this paper, after introducing essential conformity and mutuality features for secure logic encryption, we propose DLE, a novel Distributed Logic Encryption design that resists against all known oracle guided and structural attacks including the newly proposed fault-aided SAT-based attack that iteratively injects a single stuck-at fault to thwart the locking effect. DLE forces the attacker to insert multiple stuck-at faults simultaneously in critical points to achieve a smaller but meaningful encrypted circuit; thus, exponentially reducing the chance to hit all the critical points with properly located stuck-at fault injections. Our experiments confirm that DLE maintains an exponentially high degree of security under diverse attacks with the polynomial area and linear performance overheads.