1,052 research outputs found
Stealthy Opaque Predicates in Hardware -- Obfuscating Constant Expressions at Negligible Overhead
Opaque predicates are a well-established fundamental building block for
software obfuscation. Simplified, an opaque predicate implements an expression
that provides constant Boolean output, but appears to have dynamic behavior for
static analysis. Even though there has been extensive research regarding opaque
predicates in software, techniques for opaque predicates in hardware are barely
explored. In this work, we propose a novel technique to instantiate opaque
predicates in hardware, such that they (1) are resource-efficient, and (2) are
challenging to reverse engineer even with dynamic analysis capabilities. We
demonstrate the applicability of opaque predicates in hardware for both,
protection of intellectual property and obfuscation of cryptographic hardware
Trojans. Our results show that we are able to implement stealthy opaque
predicates in hardware with minimal overhead in area and no impact on latency
Antiskyrmions stabilized at interfaces by anisotropic Dzyaloshinskii-Moriya interaction
Chiral magnets are an emerging class of topological matter harbouring
localized and topologically protected vortex-like magnetic textures called
skyrmions, which are currently under intense scrutiny as a new entity for
information storage and processing. Here, on the level of micromagnetics we
rigorously show that chiral magnets cannot only host skyrmions but also
antiskyrmions as least-energy configurations over all non-trivial homotopy
classes. We derive practical criteria for their occurrence and coexistence with
skyrmions that can be fulfilled by (110)-oriented interfaces in dependence on
the electronic structure. Relating the electronic structure to an atomistic
spin-lattice model by means of density-functional calculations and minimizing
the energy on a mesoscopic scale applying spin-relaxation methods, we propose a
double layer of Fe grown on a W(110) substrate as a practical example. We
conjecture that ultrathin magnetic films grown on semiconductor or heavy metal
substrates with symmetry are prototype classes of materials hosting
magnetic antiskyrmions.Comment: 20 pages (11 pages + 9 pages supplementary material
Expression pattern of the thrombopoietin receptor (Mpl) in the murine central nervous system
<p>Abstract</p> <p>Background</p> <p>Thrombopoietin (Thpo) and its receptor (Mpl), which regulate megakaryopoiesis, are expressed in the central nervous system (CNS), where Thpo is thought to exert pro-apoptotic effects on newly generated neurons. Mpl expression has been analysed in brain tissue on transcript level and in cultured primary rat neurons and astrocytes on protein level. Herein, we analysed Mpl expression in the developing and adult murine CNS by immunohistochemistry and investigated the brain of mice with homozygous <it>Mpl </it>deficiency (<it>Mpl</it><sup>-/-</sup>) by MRI.</p> <p>Results</p> <p>Mpl was not detectable at developmental stages E12 to E15 in any resident cells of the CNS. From E18 onwards, robust Mpl expression was found in various brain areas, including cerebral cortex, olfactory bulb, thalamus, hypothalamus, medulla, pons, and the grey matter of spinal cord. However, major developmental changes became obvious: In the subventricular zone of the cerebral cortex Mpl expression occurred only during late gestation, while in the hippocampus Mpl expression was detectable for first time at stage P4. In the white matter of the cerebellum Mpl expression was restricted to the perinatal period. In the adult cerebellum, Mpl expression switched to Purkinje cell. The majority of other Mpl-positive cells were NeuN-positive neurons. None of the cells could be double-labelled with astrocyte marker GFAP. <it>Mpl</it><sup>-/- </sup>mice showed no gross abnormalities of the brain.</p> <p>Conclusions</p> <p>Our data locate Mpl expression to neurons at different subdivisions of the spinal cord, rhombencephalon, midbrain and prosencephalon. Besides neuronal cells Mpl protein is also expressed in Purkinje cells of the adult cerebellum.</p
The End of Logic Locking? A Critical View on the Security of Logic Locking
With continuously shrinking feature sizes of integrated circuits, the vast majority of semiconductor companies have become fabless, i.e., chip manufacturing has been outsourced to foundries across the globe.
However, by outsourcing critical stages of IC fabrication, the design house puts trust in entities which may have malicious intents. This exposes the design industry to a number of threats, including piracy via unauthorized overproduction and subsequent reselling on the black market.
One alleged solution for this problem is logic locking, also known as logic encryption, where the genuine functionality of a chip is “locked” using a key only known to the designer. If a correct key is provided, the design works as intended but with an incorrect key, the circuit produces faulty outputs. Unlocking is handled by the designer only after production, hence an adversarial foundry should not be able to unlock overproduced chips.
In this work, we highlight major shortcomings of proposed logic locking schemes.
They exist primarily due to the absence of a well-defined and realistic attacker model in the current literature. We characterize the physical capabilities of adversaries, especially with respect to invasive attacks and a malicious foundry.
This allows us to derive an attacker model that matches reality, yielding attacks against the foundations of locking schemes
beyond the usually employed SAT-based attacks. Our analysis, which is accompanied by two case studies, shows that none of the previously proposed logic locking schemes is able to achieve the intended protection goals against piracy in real-world scenarios.
As an important conclusion, we argue that there are strong indications that logic locking will most likely never be secure against a determined malicious foundry
Anleitung zur Organisation von Webkonferenzen am Beispiel der “Bibcast”-Aktion zum Bibliothekskongress 2016
Zwischen dem 7. und 11. März 2016 fand der erste Bibcast, eine Webcast-Serie zu bibliothekarisch relevanten Themen statt. Aus der Idee heraus entstanden, abgelehnten Einreichungen für den Bibliothekskongress ein alternatives Forum zu bieten, hat sich der Bibcast als interessantes, flexibles und innovatives Format herausgestellt, das die Landschaft der Präsenzkonferenzen zukünftig sinnvoll ergänzen kann. In diesem Praxisbeitrag soll über Entstehung und Ablauf berichtet, Mehrwerte und Stolpersteine veranschaulicht und damit zugleich eine Anleitung zur Organisation von Webkonferenzen gegeben werden
The topological susceptibility of SU(3) gauge theory near T_c
We compute the topological susceptibility chi_t in SU(3) lattice gauge theory
using fermionic methods based on the Atiyah-Singer index theorem. Near the
phase transition we find a smooth crossover behavior for chi_t with values
decreasing from (191(5) MeV)^4 to (100(5) MeV)^4 as we increase the temperature
from 0.88 T_c to 1.31 T_c, showing that topological excitations exist far above
T_c. Our study is the first large scale analysis of the topological
susceptibility at high temperature based on the index theorem and the results
agree well with field theoretical methods.Comment: Concluding statement reworded. To appear in Physics Letters
Increasing the efficiency of local energy markets through residential demand response
Local energy markets (LEMs) aim at building up local balances of generation and
demand close to real time. A bottom-up energy system made up of several LEMs could
reduce energy transmission, renewable curtailment and redispatch measures in the
long-term, if managed properly. However, relying on limited local resources, LEMs
require flexibility to achieve a high level of self-sufficiency. We introduce demand
response (DR) into LEMs as a means of flexibility in residential demand that can be used
to increase local self-sufficiency, decrease residual demand power peaks, facilitate local
energy balances and reduce the cost of energy supply. We present a simulation study
on a 100 household LEM and show how local sufficiency can be increased up to 16%
with local trading and DR. We study three German regulatory scenarios and derive that
the electricity price and the annual residual peak demand can be reduced by up to
10ce/kWh and 40
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