Our society has become increasingly dependent on electronic information exchange between personal devices and network servers. New ways of buying and paying, such as electronic-commerce and mobile-banking, have become popular. Unfortunately, the security of such transactions is constantly being challenged. In spite of the recent advances in network and cloud security, there have been several identity and secure information leaks in Target, Home Depot, Apple and Sony Pictures Entertainment, etc. . Many of the security breaches are due to insecure access channels to the cloud. An adversary can obtain user credentials through a counterfeited device and access the74 cloud from anywhere. The security problem is likely to be exacerbated in the Internet-of-things (IoT) era where millions of devices in our homes, offices, and cars are digitally connected. It is estimated that the number of connected devices will reach 50 billion in 2020 . Every connected IoT device provides more attack possibilities and adds to the potential risk. Thus, security has to be built into all layers of the system from network and cloud layers to the IoT hardware layer. Adding to the complexity is the fact that the integrated circuit (IC)'s global and distributed supply chain has introduced hardware-based security issues, such as hardware Trojans, intellectual property (IP) piracy and IC overbuilding, reverse engineering, counterfeiting, etc. . Thus, hardware trustworthiness is even more important in the IoT era. Each IoT device should be equipped with a unique device signature that can be used for authentication by the cloud .
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