Design Tradeoffs in Threshold Implementations With the expansion of the IoT and the emergence of vast amounts of remote hardware devices sidechannel attacks pose a serious threat, requiring adequate protection. Among the hardware countermeasures, Threshold Implementations (TI) is one of the most used ones. It is designed to avoid the leakage of sensitive data from hardware designs. In this work, we examine the cost of applying TI to the block cipher PRINCE with respect to the latency, powerenergy consumption, occupied area. We explore different versions of TI with respect to the security order and TI variations, and compare the strengths and weaknesses of each approach.

Adaptive Masking: a Dynamic Tradeoff between Energy Consumption and Hardware Security As the Internet of Things (IoT) devices process and communicate an increasing amount of sensitive data, the confidentiality of these data is a growing concern. Hardware sidechannel attacks pose a threat against the physical implementation of encryption, which is commonly used to ensure this confidentiality. Traditional hardware countermeasures against such sidechannel attacks, like masking, usually introduce a high energy overhead. However, IoT devices are typically resourceconstrained and have a small energy budget. Furthermore, the energy or security constraints may vary between devices or over time, depending on, e.g., the remaining battery level or data sensitivity. Therefore, a dynamic tradeoff has to be found between security, power consumption and performance. In this paper, we introduce a new paradigm whereby hardware masking is applied on demand to increase the energy efficiency. We illustrate this concept by applying it to the stream cipher Trivium. We demonstrate that compared to a reference masked implementation, this solution ensures a high level of security when necessary while significantly reducing the power consumption (by up to 76.2%) the rest of the time, with a small area overhead (13.5%) and no impact on the performance.