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.