Detection of Trojan HW by using hidden information on the system

A Trojan horse is a malicious altering of hardware specification or implementation in such a way that its functionality is altered under a set of conditions defined by the attacker. The paper presents a technique for designing secure systems that can detect an active Trojan. The technique is based on utilizing specific information about the system's behavior, which is known to the designer of the system and/or is hidden in the functional specification of the system. A case study of the proposed technique conducted on an arithmetic unit of a microprocessor is provided. The study indicated a high level of Trojan detection with a small hardware overhead.