Security of Functionally Obfuscated DSP Core Against Removal Attack Using SHA-512 Based Key Encryption Hardware

Digital signal processing (DSP) kernel-based intellectual property (IP) core forms an integral ingredient of consumer electronics devices. Thus, protection of these IP cores against reverse engineering attack is crucial. Functional obfuscation serves as a powerful mechanism to counter this hardware threat. However, functional obfuscation methodologies for DSP cores use security logics that are not lightweight and are prone to removal attack by an adversary. This paper presents a novel security mechanism for protecting functionally obfuscated DSP core against removal attack using low-cost, low-power key encryption hardware. The proposed methodology using lightweight secure hashing algorithm (SHA-512)-based key encryption custom hardware reconfigures the key-bits (resulting into structural reconfiguration) of the locking logic in a functionally obfuscated DSP design augmented with the complete logic synthesis of the design. This hinders the detection of the locking logic in the obfuscated design due to camouflaging. The proposed mechanism integrated with the functional obfuscation framework yielded lower power, lower gate count, and enhanced security compared with an existing approach. An average reduction of 25.86 % in gate count and power as well as the average enhancement of 43.75 % in security against removal attack was obtained in the proposed approach compared with a recent existing approach.