A Hardware Trojan (HT) is a malicious modification of the circuitry of an integrated circuit. A hardware Trojan is completely characterized by its physical representation and its behavior. The payload of an HT is the entire activity that the Trojan executes when it is triggered. In general, malicious Trojans try to bypass or disable the security fence of a system: It can leak confidential information by radio emission. HT's also could disable, derange or destroy the entire chip or components of it.