3,215 research outputs found
Practical cryptographic strategies in the post-quantum era
We review new frontiers in information security technologies in
communications and distributed storage technologies with the use of classical,
quantum, hybrid classical-quantum, and post-quantum cryptography. We analyze
the current state-of-the-art, critical characteristics, development trends, and
limitations of these techniques for application in enterprise information
protection systems. An approach concerning the selection of practical
encryption technologies for enterprises with branched communication networks is
introduced.Comment: 5 pages, 2 figures; review pape
Quantum-secured blockchain
Blockchain is a distributed database which is cryptographically protected
against malicious modifications. While promising for a wide range of
applications, current blockchain platforms rely on digital signatures, which
are vulnerable to attacks by means of quantum computers. The same, albeit to a
lesser extent, applies to cryptographic hash functions that are used in
preparing new blocks, so parties with access to quantum computation would have
unfair advantage in procuring mining rewards. Here we propose a possible
solution to the quantum era blockchain challenge and report an experimental
realization of a quantum-safe blockchain platform that utilizes quantum key
distribution across an urban fiber network for information-theoretically secure
authentication. These results address important questions about realizability
and scalability of quantum-safe blockchains for commercial and governmental
applications.Comment: 7 pages, 2 figures; published versio
Stress-strain analysis of pipelines laid in permafrost
Increasing reliability of pipelines becomes a real challenge at all stages: design, construction and operation of pipeline systems. It is very important to determine the behaviour of the constructed pipeline under the operational and environmental loads using the design model in accordance with that one adopted in the rules and regulations. This article presents the simulation of pipeline in permafrost. The evaluation of the stress-strain state is given herein and the areas of the stress concentration are detected with the account for different loads occurred during the pipeline operation. Information obtained from the assessment of the stress-strain state of the pipeline allows determining sections in pre-emergency state (even before damages) and take all the necessary measures for eliminating them, thus increasing the pipeline system reliability. It is shown that the most critical pipeline cross-section is observed at the point of transition from one environment to another. The maximum strains decrease the level of the pipeline reliability. The finite element model is presented to determine the pipeline sections in pre-emergency state
Time-Series Photometry of M67: W UMa Systems, Blue Stragglers, and Related Systems
We present an analysis of over 2200 V images taken on 14 nights at the Mt.
Laguna 1 m telescope of the open cluster M67. Our observations overlap but
extend beyond the field analyzed by Gilliland et al. (1991), and complement
data recently published by van den Berg et al. (2002) and Stassun et al.
(2002). We show variability in the light curves of all 4 of the known W UMa
variables on timescales ranging from a day to decades (for AH Cnc). We have
modeled the light curve of AH Cnc, and the total eclipses allow us to determine
q = 0.16 +0.03/-0.02 and i = 86 +4/-8 degrees. The position of this system near
the turnoff of M67 makes it useful for constraining the turnoff mass for the
cluster. We have also detected two unusual features in the light curve of AH
Cnc that may be caused by prominences. We have also monitored cluster blue
stragglers for variability, and we present evidence hinting at low level
variations in the stragglers S752, S968, and S1263, and we place limits on the
variability of a number of other cluster blue stragglers. Finally, we provide
photometry of the sub-subgiant branch star S1063 showing variability on
timescales similar to the orbital period, while the ``red straggler'' S1040
shows evidence of an unexplained drop in brightness at phases corresponding to
the passage of the white dwarf in front of the giant.Comment: 44 pages, 16 figures, AASTeX, accepted for A
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