Hardwar Trojan classification and implementation and offer a new detection approach

A hardware attack that enables the attacker to alter the main circuit with malicious hardware during either design or the fabrication process is studied and analyzed. This attack, known as the hardware Trojan, has different objectives such as destroying hardware, changing circuit characteristics or extracting sensitive information. So hardware Trojan detection and hardware security are critical issues. First, we categorize the Trojans and Trojan detection methods and then implement four types of Trojan on DES algorithm. Then a hardware approach to the detection of hardware Trojans based on the characteristics of circuit delay is proposed. In this approach, ring oscillator frequencies are inputs of the circuit under test, and output is a string of bits corresponding to challenges. The proposed hardware is designed to address any changes in the main circuit that would affect the frequency of the ring oscillator factors, such as temperature, voltage, and process variations that influence the frequency of the ring oscillator are analyzed, and a suitable ring oscillator is recommended for embedding into the circuit. As a result, the frequency variation will be reduced dramatically, and it can be determined with higher certainty whether changes in frequency are result of a possible Trojan.As a result the output bit string, which is now unaffected by frequency changes due to process variation, can be used as a measure to detect hardware Trojans.