Outsourcing of IC manufacturing has opened the possibility of intentionally modifying the operation of the IC in a subtle way so that it is extremely difficult to detect, in conventional functional testing. Security in computation is no longer a software only issue, the underlying computing hardware may also be compromised. As occurrence of Trojan activation is rare event, it needs to be detected without actually activating it. In digital systems Trojan payload takes input from low activity nodes of the original circuit. Even when the Trojan is not activated, these tapings of original circuit nodes exhibit extra capacitive load. This work is geared towards detecting these extra capacitances with unprecedented accuracy to uncover malicious Trojans in the circuit. We have shown that pulse propagation in logic circuit can be used to detect any extra stray capacitance at any circuit node with 20-25X better diagnostic resolution than that of any other delay and frequency measurement based techniques. We have developed a current sensor that monitors supply currents at predetermined low activity gates. If any one of these nodes are tapped for Trojan, then due to extra capacitive load the applied pulse gets killed and the difference maximum current (before and after pulse) indicate Trojan occurrence. While majority of the Trojan detection techniques loose diagnostic accuracy with the size of the circuit and amount of process variation, diagnostic capability of the proposed pulse based technique is independent of size of the circuit. The proposed scheme can be integrated into JTAG boundary scan to provide a complete solution for hardware Trojan detection in digital systems.

IC制造的外包开辟了一种可能性，即可以以微妙的方式有意地修改IC的操作，从而在常规功能测试中很难检测到它。计算的安全性不再仅仅是软件问题，底层的计算硬件也可能受到威胁。由于特洛伊木马激活很少发生，因此无需实际激活即可对其进行检测。在数字系统中，特洛伊木马有效负载从原始电路的低活动节点获取输入。即使未激活特洛伊木马程序，原始电路节点的这些接头也会显示出额外的容性负载。这项工作旨在以前所未有的精度检测这些额外的电容，以发现电路中的恶意木马。我们已经证明，逻辑电路中的脉冲传播可用于检测任何电路节点处的任何额外杂散电容，其诊断分辨率比任何其他基于延迟和频率测量的技术要好20-25倍。我们已经开发了一种电流传感器，该传感器可以监视预定的低活动门限处的电源电流。如果为木马攻入了这些节点中的任何一个，则由于额外的容性负载，所施加的脉冲被杀死，并且最大电流差（脉冲前后）表明木马出现了。尽管大多数特洛伊木马检测技术会随电路大小和过程变化量降低诊断精度，但所提出的基于脉冲的技术的诊断能力与电路大小无关。