A critical view on the real-world security of logic locking.

With continuously shrinking feature sizes of integrated circuits, the vast majority of semiconductor companies have become fabless, outsourcing to foundries across the globe. This exposes the design industry to a number of threats, including piracy via IP-theft or unauthorized overproduction and subsequent reselling on the black market. One alleged solution for this problem is logic locking, where the genuine functionality of a chip is "locked" using a key only known to the designer. Solely with a correct key, the design works as intended. Since unlocking is handled by the designer only after production, an adversary in the supply chain should not be able to unlock overproduced chips. In this work, we focus on logic locking against the threat of overproduction. First, we survey existing locking schemes and characterize them by their handling of keys, before extracting similarities and differences in the employed attacker models. We then compare said models to the real-world capabilities of the primary adversary in overproduction-a malicious foundry. This comparison allows us to identify pitfalls in existing models and derive a more realistic attacker model. Then, we discuss how existing schemes hold up against the new attacker model. Our discussion highlights that several attacks beyond the usually employed SAT-based approaches are viable. Crucially, these attacks stem from the underlying structure of current logic locking approaches, which has never changed since its introduction in 2008. We conclude that logic locking, while being a promising approach, needs a fundamental rethinking to achieve real-world protection against overproduction.

Aneurysmal Subarachnoid Hemorrhage during the Shutdown for COVID-19.

The aim was to evaluate hospitalization rates for aneurysmal subarachnoid hemorrhage (SAH) within an interdisciplinary multicenter neurovascular network (NVN) during the shutdown for the COVID-19 pandemic along with its modifiable risk factors. In this multicenter study, admission rates for SAH were compared for the period of the shutdown for the COVID-19 pandemic in Germany (calendar weeks (cw) 12 to 16, 2020), the periods before (cw 6-11) and after the shutdown (cw 17-21 and 22-26, 2020), as well as with the corresponding cw in the years 2015-2019. Data on all-cause and pre-hospital mortality within the area of the NVN were retrieved from the Department of Health, and the responsible emergency medical services. Data on known triggers for systemic inflammation, e.g., respiratory viruses and air pollution, were analyzed. Hospitalizations for SAH decreased during the shutdown period to one-tenth within the multicenter NVN. There was a substantial decrease in acute respiratory illness rates, and of air pollution during the shutdown period. The implementation of public health measures, e.g., contact restrictions and increased personal hygiene during the shutdown, might positively influence modifiable risk factors, e.g., systemic inflammation, leading to a decrease in the incidence of SAH.

NADPH oxidase 2 mediates angiotensin II-dependent cellular arrhythmias via PKA and CaMKII.

RATIONALE: Angiotensin II (Ang II) signaling has been implicated in cardiac arrhythmogenesis, which involves induction of reactive oxygen species (ROS). It was shown that Ang II can activate Ca/Calmodulin kinase II (CaMKII) by oxidation via a NADPH oxidase 2 (NOX2)-dependent pathway leading to increased arrhythmic afterdepolarizations. Interestingly, cAMP-dependent protein kinase A (PKA) which regulates similar targets as CaMKII has recently been shown to be redox-sensitive as well. OBJECTIVE: This study aims to investigate the distinct molecular mechanisms underlying Ang II-related cardiac arrhythmias with an emphasis on the individual contribution of PKA vs. CaMKII. METHODS AND RESULTS: Isolated ventricular cardiac myocytes from rats and mice were used. Ang II exposure resulted in increased NOX2-dependent ROS generation assessed by expression of redox-sensitive GFP and in myocytes loaded with ROS indicator MitoSOX. Whole cell patch clamp measurements showed that Ang II significantly increased peak Ca and Na current (ICa and INa) possibly by enhancing steady-state activation of ICa and INa. These effects were absent in myocytes lacking functional NOX2 (gp91phox(-/-)). In parallel experiments using PKA inhibitor H89, the Ang II effects on peak INa and ICa were also absent. In contrast, genetic knockout of CaMKIIδ (CaMKIIδ(-/-)) did not influence the Ang II-dependent increase in peak ICa and INa. On the other hand, Ang II enhanced INa inactivation, increased late INa and induced diastolic SR (sarcoplasmic reticulum) Ca leak (confocal Ca spark measurements) in a CaMKIIδ-, but not PKA-dependent manner. Surprisingly, only the increase in diastolic SR Ca leak was absent in gp91phox(-/-)myocytes suggesting that Ang II regulates INa inactivation in a manner dependent on CaMKII- but not on NOX2. Finally, we show that Ang II increased the propensity for cellular arrhythmias, for which PKA and CaMKII contribute, both dependent on NOX2. CONCLUSION: Ang II activates PKA and CaMKII via NOX2, which results in disturbed Na and Ca currents (via PKA) and enhanced diastolic SR Ca leakage (via CaMKII). Oxidative activation of PKA and CaMKII via NOX2 may represent important pro-arrhythmogenic pathways in the setting of increased Ang II stimulation, which may be relevant for the treatment of arrhythmias in cardiac disease.