In our digital world, integrated circuits are present in nearly every moment of our daily life. Even when using the coffee machine in the morning, or driving our car to work, we interact with integrated circuits. The increasing spread of information technology in virtually all areas of life in the industrialized world offers a broad range of attack vectors. So far, mainly software-based attacks have been considered and investigated, while hardware-based attacks have attracted comparatively little interest. The design and production process of integrated circuits is mostly decentralized due to financial and logistical reasons. Therefore, a high level of trust has to be established between the parties involved in the hardware development lifecycle. During the complex production chain, malicious attackers can insert non-specified functionality by exploiting untrusted processes and backdoors. This work deals with the ways in which such hidden, non-specified functionality can be introduced