23,927 research outputs found
LightBox: Full-stack Protected Stateful Middlebox at Lightning Speed
Running off-site software middleboxes at third-party service providers has
been a popular practice. However, routing large volumes of raw traffic, which
may carry sensitive information, to a remote site for processing raises severe
security concerns. Prior solutions often abstract away important factors
pertinent to real-world deployment. In particular, they overlook the
significance of metadata protection and stateful processing. Unprotected
traffic metadata like low-level headers, size and count, can be exploited to
learn supposedly encrypted application contents. Meanwhile, tracking the states
of 100,000s of flows concurrently is often indispensable in production-level
middleboxes deployed at real networks.
We present LightBox, the first system that can drive off-site middleboxes at
near-native speed with stateful processing and the most comprehensive
protection to date. Built upon commodity trusted hardware, Intel SGX, LightBox
is the product of our systematic investigation of how to overcome the inherent
limitations of secure enclaves using domain knowledge and customization. First,
we introduce an elegant virtual network interface that allows convenient access
to fully protected packets at line rate without leaving the enclave, as if from
the trusted source network. Second, we provide complete flow state management
for efficient stateful processing, by tailoring a set of data structures and
algorithms optimized for the highly constrained enclave space. Extensive
evaluations demonstrate that LightBox, with all security benefits, can achieve
10Gbps packet I/O, and that with case studies on three stateful middleboxes, it
can operate at near-native speed.Comment: Accepted at ACM CCS 201
Super cavity solitons and the coexistence of multiple nonlinear states in a tristable passive Kerr resonator
Passive Kerr cavities driven by coherent laser fields display a rich
landscape of nonlinear physics, including bistability, pattern formation, and
localised dissipative structures (solitons). Their conceptual simplicity has
for several decades offered an unprecedented window into nonlinear cavity
dynamics, providing insights into numerous systems and applications ranging
from all-optical memory devices to microresonator frequency combs. Yet despite
the decades of study, a recent theoretical study has surprisingly alluded to an
entirely new and unexplored paradigm in the regime where nonlinearly tilted
cavity resonances overlap with one another [T. Hansson and S. Wabnitz, J. Opt.
Soc. Am. B 32, 1259 (2015)]. We have used synchronously driven fiber ring
resonators to experimentally access this regime, and observed the rise of new
nonlinear dissipative states. Specifically, we have observed, for the first
time to the best of our knowledge, the stable coexistence of dissipative
(cavity) solitons and extended modulation instability (Turing) patterns, and
performed real time measurements that unveil the dynamics of the ensuing
nonlinear structures. When operating in the regime of continuous wave
tristability, we have further observed the coexistence of two distinct cavity
soliton states, one of which can be identified as a "super" cavity soliton as
predicted by Hansson and Wabnitz. Our experimental findings are in excellent
agreement with theoretical analyses and numerical simulations of the
infinite-dimensional Ikeda map that governs the cavity dynamics. The results
from our work reveal that experimental systems can support complex combinations
of distinct nonlinear states, and they could have practical implications to
future microresonator-based frequency comb sources.Comment: 13 pages, 6 figure
Three-dimensional alpha shapes
Frequently, data in scientific computing is in its abstract form a finite
point set in space, and it is sometimes useful or required to compute what one
might call the ``shape'' of the set. For that purpose, this paper introduces
the formal notion of the family of -shapes of a finite point set in
\Real^3. Each shape is a well-defined polytope, derived from the Delaunay
triangulation of the point set, with a parameter \alpha \in \Real controlling
the desired level of detail. An algorithm is presented that constructs the
entire family of shapes for a given set of size in time , worst
case. A robust implementation of the algorithm is discussed and several
applications in the area of scientific computing are mentioned.Comment: 32 page
Still Wrong Use of Pairings in Cryptography
Several pairing-based cryptographic protocols are recently proposed with a
wide variety of new novel applications including the ones in emerging
technologies like cloud computing, internet of things (IoT), e-health systems
and wearable technologies. There have been however a wide range of incorrect
use of these primitives. The paper of Galbraith, Paterson, and Smart (2006)
pointed out most of the issues related to the incorrect use of pairing-based
cryptography. However, we noticed that some recently proposed applications
still do not use these primitives correctly. This leads to unrealizable,
insecure or too inefficient designs of pairing-based protocols. We observed
that one reason is not being aware of the recent advancements on solving the
discrete logarithm problems in some groups. The main purpose of this article is
to give an understandable, informative, and the most up-to-date criteria for
the correct use of pairing-based cryptography. We thereby deliberately avoid
most of the technical details and rather give special emphasis on the
importance of the correct use of bilinear maps by realizing secure
cryptographic protocols. We list a collection of some recent papers having
wrong security assumptions or realizability/efficiency issues. Finally, we give
a compact and an up-to-date recipe of the correct use of pairings.Comment: 25 page
Disk Heating, Galactoseismology, and the Formation of Stellar Halos
Deep photometric surveys of the Milky Way have revealed diffuse structures
encircling our Galaxy far beyond the "classical" limits of the stellar disk.
This paper reviews results from our own and other observational programs, which
together suggest that, despite their extreme positions, the stars in these
structures were formed in our Galactic disk. Mounting evidence from recent
observations and simulations implies kinematic connections between several of
these distinct structures. This suggests the existence of collective disk
oscillations that can plausibly be traced all the way to asymmetries seen in
the stellar velocity distribution around the Sun. There are multiple
interesting implications of these findings: they promise new perspectives on
the process of disk heating, they provide direct evidence for a stellar halo
formation mechanism in addition to the accretion and disruption of satellite
galaxies, and, they motivate searches of current and near-future surveys to
trace these oscillations across the Galaxy. Such maps could be used as
dynamical diagnostics in the emerging field of "Galactoseismology", which
promises to model the history of interactions between the Milky Way and its
entourage of satellites, as well examine the density of our dark matter halo.
As sensitivity to very low surface brightness features around external galaxies
increases, many more examples of such disk oscillations will likely be
identified. Statistical samples of such features not only encode detailed
information about interaction rates and mergers, but also about long
sought-after dark matter halo densities and shapes. Models for the Milky Way's
own Galactoseismic history will therefore serve as a critical foundation for
studying the weak dynamical interactions of galaxies across the universe.Comment: 20 pages, 5 figures, accepted in for publication in a special edition
of the journal "Galaxies", reporting the proceedings of the conference "On
the Origin (and Evolution) of Baryonic Galaxy Halos", Puerto Ayora, Ecuador,
March 13-17 2017, Eds. Duncan A. Forbes and Ericson D. Lope
Ionospheric Multi-Spacecraft Analysis Tools
This open access book provides a comprehensive toolbox of analysis techniques for ionospheric multi-satellite missions. The immediate need for this volume was motivated by the ongoing ESA Swarm satellite mission, but the tools that are described are general and can be used for any future ionospheric multi-satellite mission with comparable instrumentation. In addition to researching the immediate plasma environment and its coupling to other regions, such a mission aims to study the Earth’s main magnetic field and its anomalies caused by core, mantle, or crustal sources. The parameters for carrying out this kind of work are examined in these chapters. Besides currents, electric fields, and plasma convection, these parameters include ionospheric conductance, Joule heating, neutral gas densities, and neutral winds.
Quantum entanglement in photosynthetic light harvesting complexes
Light harvesting components of photosynthetic organisms are complex, coupled,
many-body quantum systems, in which electronic coherence has recently been
shown to survive for relatively long time scales despite the decohering effects
of their environments. Within this context, we analyze entanglement in
multi-chromophoric light harvesting complexes, and establish methods for
quantification of entanglement by presenting necessary and sufficient
conditions for entanglement and by deriving a measure of global entanglement.
These methods are then applied to the Fenna-Matthews-Olson (FMO) protein to
extract the initial state and temperature dependencies of entanglement. We show
that while FMO in natural conditions largely contains bipartite entanglement
between dimerized chromophores, a small amount of long-range and multipartite
entanglement exists even at physiological temperatures. This constitutes the
first rigorous quantification of entanglement in a biological system. Finally,
we discuss the practical utilization of entanglement in densely packed
molecular aggregates such as light harvesting complexes.Comment: 14 pages, 7 figures. Improved presentation, published versio
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