157 research outputs found
La pĂȘche palangriĂšre asiatique dans la Z.E.E. de PolynĂ©sie Française : analyse des donnĂ©es disponibles pour la pĂ©riode 1984-1992
Pseudo Identities Based on Fingerprint Characteristics
This paper presents the integrated project TURBINE which is funded under the EU 7th research framework programme. This research is a multi-disciplinary effort on privacy enhancing technology, combining innovative developments in cryptography and fingerprint recognition. The objective of this project is to provide a breakthrough in electronic authentication for various applications in the physical world and on the Internet. On the one hand it will provide secure identity verification thanks to fingerprint recognition. On the other hand it will reliably protect the biometric data through advanced cryptography technology. In concrete terms, it will provide the assurance that (i) the data used for the authentication, generated from the fingerprint, cannot be used to restore the original fingerprint sample, (ii) the individual will be able to create different "pseudo-identities" for different applications with the same fingerprint, whilst ensuring that these different identities (and hence the related personal data) cannot be linked to each other, and (iii) the individual is enabled to revoke an biometric identifier (pseudo-identity) for a given application in case it should not be used anymore
The Cherenkov Telescope Array Large Size Telescope
The two arrays of the Very High Energy gamma-ray observatory Cherenkov
Telescope Array (CTA) will include four Large Size Telescopes (LSTs) each with
a 23 m diameter dish and 28 m focal distance. These telescopes will enable CTA
to achieve a low-energy threshold of 20 GeV, which is critical for important
studies in astrophysics, astroparticle physics and cosmology. This work
presents the key specifications and performance of the current LST design in
the light of the CTA scientific objectives.Comment: 4 pages, 5 figures, In Proceedings of the 33rd International Cosmic
Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at
arXiv:1307.223
Contrasting Habitat Use and Population Dynamics of Reef Manta Rays Within the Nusa Penida Marine Protected Area, Indonesia
Manta rays (Mobula spp.) are highly valued in nature-based tourism globally. In Indonesia, although manta rays are protected, critical information is lacking on their habitat use, population dynamics and movements. We investigate the population structure and residency patterns of reef manta rays (Mobula alfredi) in the Nusa Penida Marine Protected Area (MPA). From photo-identification data logged by citizen scientists and trained observers (mantamatcher.org), we identified 624 reef manta rays from 5,913 sightings (January 2012âApril 2018) based on their unique ventral coloration patterns. Year-round records were collected from two shallow (<20 m) reefs â Manta Bay (MB; n = 3,029 sightings) and Manta Point (MP; n = 3,058) â that are used frequently by tourism operators. Maximum likelihood techniques and a Markov movement analysis were used to model residency patterns and movement between these sites within the MPA. Manta rays at MB were predominantly male (64%, n = 261 individuals), with immature males (14%, n = 59) being sighted most frequently (39%, n = 1,170). In contrast, few immature individuals were sighted at MP (6%, n = 28), and they were sighted on few occasions (2%, n = 45), while mature female manta rays comprised 26% (n = 127) of the MP community and were the most frequently sighted (48%, n = 1,413). Lagged identification rates indicated high site fidelity at each location. However, 44% (n = 278) of individuals moved between the two sites and cumulative discovery curves showed a continued recruitment of individuals over the 6 years of the study. In addition, the behaviors displayed by the manta rays differed markedly between the two sites: MB appears to be a foraging ground, especially for juveniles, and potentially a nursery, while MP is used mainly for cleaning and courtship, indicating a social and reproductive site. Reproductive behavior coincided with the peak annual sightings in May. To prevent disturbance to this threatened species by tourism, regulations for the number of boats and interactions, especially during key reproductive times should be considered. Further, strict fishing regulation in the area is recommended as fishing gear entanglement was identified as a threat to this population
NectarCAM : a camera for the medium size telescopes of the Cherenkov Telescope Array
NectarCAM is a camera proposed for the medium-sized telescopes of the
Cherenkov Telescope Array (CTA) covering the central energy range of ~100 GeV
to ~30 TeV. It has a modular design and is based on the NECTAr chip, at the
heart of which is a GHz sampling Switched Capacitor Array and a 12-bit Analog
to Digital converter. The camera will be equipped with 265 7-photomultiplier
modules, covering a field of view of 8 degrees. Each module includes the
photomultiplier bases, high voltage supply, pre-amplifier, trigger, readout and
Ethernet transceiver. The recorded events last between a few nanoseconds and
tens of nanoseconds. The camera trigger will be flexible so as to minimize the
read-out dead-time of the NECTAr chips. NectarCAM is designed to sustain a data
rate of more than 4 kHz with less than 5\% dead time. The camera concept, the
design and tests of the various subcomponents and results of thermal and
electrical prototypes are presented. The design includes the mechanical
structure, cooling of the electronics, read-out, clock distribution, slow
control, data-acquisition, triggering, monitoring and services.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Generic Construction of Hybrid Public Key Traitor Tracing with Full-Public-Traceability
Abstract. In Eurocrypt 2005, Chabanne, Phan and Pointcheval introduced an interesting property for traitor tracing schemes called public traceability, which makes tracing a black-box public operation. However, their proposed scheme only worked for two users and an open question proposed by authors was to provide this property for multi-user systems. In this paper, we give a comprehensive solution to this problem by giving a generic construction for a hybrid traitor tracing scheme that provides full-public-traceability. We follow the Tag KEM/DEM paradigm of hybrid encryption systems and extend it to multi-receiver scenario. We define Tag-BroadcastKEM/DEM and construct a secure Tag-BroadcastKEM from a CCA secure PKE and target-collision resistant hash function. We will then use this Tag-BroadcastKEM together with a semantically secure DEM to give a generic construction for Hybrid Public Key Broadcast Encryption. The scheme has a black box tracing algorithm that always correctly identifies a traitor. The hybrid structure makes the system very efficient, both in terms of computation and communication cost. Finally we show a method of reducing the communication cost by using codes with identifiable parent property.
A Concise Bounded Anonymous Broadcast Yielding Combinatorial Trace-and-Revoke Schemes
Broadcast Encryption is a fundamental primitive supporting sending a secure message to any chosen target set of users.
While many efficient constructions are known, understanding the efficiency possible for an ``Anonymous Broadcast Encryption\u27\u27 (ANOBE), i.e., one which can hide the target set itself, is quite open. The best solutions by Barth, Boneh, and Waters (\u2706) and Libert, Paterson, and Quaglia (\u2712) are built on public key encryption (PKE) and their ciphertext sizes are, in fact, times that of the underlying PKE (rate=). Kiayias and Samary (\u2712), in turn, showed a lower bound showing that such rate is the best possible if is an independent unbounded parameter. However, when considering certain user set size bounded by a system parameter (e.g., the security parameter), the problem remains interesting. We consider the problem of comparing ANOBE with PKE under the same assumption. We call such schemes Anonymous Broadcast Encryption for Bounded Universe -- AnoBEB.
We first present an AnoBEB construction for up to users from LWE assumption, where is bounded by the scheme security parameter. The scheme does not grow with the parameter and beat the PKE method. Actually, our scheme is as efficient as the underlying LWE public-key encryption; namely, the rate is, in
fact, and thus optimal. The scheme is achieved easily by an observation about an earlier scheme with a different purpose.
More interestingly, we move on to employ the new AnoBEB in other multimedia broadcasting methods and, as a second contribution, we introduce a new approach to construct an efficient ``Trace and Revoke scheme\u27\u27 which combines the functionalites of revocation and of tracing people (called traitors) who in a broadcasting schemes share their keys with the adversary which, in turn, generates a pirate receiver. Note that, as was put forth by Kiayias and Yung (EUROCRYPT \u2702), combinatorial traitor tracing schemes can be constructed by combining a system for small universe, integrated via an outer traceability codes (collusion-secure code or identifying parent property (IPP) code). There were many efficient traitor tracing schemes from traceability codes, but no known scheme supports revocation as well. Our new approach integrates our AnoBEB system with a Robust IPP code, introduced by Barg and Kabatiansky (IEEE IT \u2713). This shows an interesting use for robust IPP in cryptography.
The robust IPP codes were only implicitly shown by an existence proof. In order to make our technique concrete, we propose two explicit instantiations of robust IPP codes. Our final construction gives the most efficient trace and revoke scheme in the bounded collusion model
Risky Traitor Tracing and New Differential Privacy Negative Results
In this work we seek to construct collusion-resistant traitor tracing systems with small ciphertexts
from standard assumptions that also move toward practical efficiency. In our approach we will hold
steadfast to the principle of collusion resistance, but relax the requirement on catching a traitor from
a successful decoding algorithm. We define a -risky traitor tracing system as one where the probability of identifying
a traitor is times the probability a successful box is produced. We then go on to show
how to build such systems from prime order bilinear groups with assumptions close to those used in prior works.
Our core system achieves, for any , where ciphertexts consists of group elements
and decryption requires pairing operations.
At first glance the utility of such a system might seem questionable since the we achieve for short ciphertexts
is relatively small. Indeed an attacker in such a system can more likely than not get away with producing a decoding box.
However, we believe this approach to be viable for four reasons:
1. A risky traitor tracing system will provide deterrence against risk averse attackers. In some settings the
consequences of being caught might bear a high cost and an attacker will have to weigh his utility of producing a
decryption box against the expected cost of being caught.
2. Consider a broadcast system where we want to support low overhead broadcast encrypted communications, but
will periodically allow for a more expensive key refresh operation. We refer to an adversary produced algorithm that
maintains the ability to decrypt across key refreshes as a persistent decoder. We show how if we employ a risky traitor
tracing systems in this setting, even for a small , we can amplify the chances of catching such a ``persistent decoder\u27\u27 to
be negligibly close to 1.
3. In certain resource constrained settings risky traitor tracing provides a best tracing effort where
there are no other collusion-resistant alternatives. For instance, suppose we had to support 100K users
over a radio link that had just 10KB of additional resources for extra ciphertext overhead. None of the
existing bilinear map systems can fit in these constraints. On the other
hand a risky traitor tracing system provides a spectrum of tracing probability versus overhead tradeoffs and can
be configured to at least give some deterrence in this setting.
4. Finally, we can capture impossibility results for differential privacy from -risky traitor tracing. Since our
ciphertexts are short (), we get the negative result which matches what one would get plugging
in the obfuscation based tracing system Boneh-Zhandry (CRYPTO 2014) solution into the prior impossibility result
of Dwork et al. (STOC 2009)
Utilization of mechanical power and associations with clinical outcomes in brain injured patients. a secondary analysis of the extubation strategies in neuro-intensive care unit patients and associations with outcome (ENIO) trial
BackgroundThere is insufficient evidence to guide ventilatory targets in acute brain injury (ABI). Recent studies have shown associations between mechanical power (MP) and mortality in critical care populations. We aimed to describe MP in ventilated patients with ABI, and evaluate associations between MP and clinical outcomes.MethodsIn this preplanned, secondary analysis of a prospective, multi-center, observational cohort study (ENIO, NCT03400904), we included adult patients with ABI (Glasgow Coma Scale <= 12 before intubation) who required mechanical ventilation (MV) >= 24 h. Using multivariable log binomial regressions, we separately assessed associations between MP on hospital day (HD)1, HD3, HD7 and clinical outcomes: hospital mortality, need for reintubation, tracheostomy placement, and development of acute respiratory distress syndrome (ARDS).ResultsWe included 1217 patients (mean age 51.2 years [SD 18.1], 66% male, mean body mass index [BMI] 26.3 [SD 5.18]) hospitalized at 62 intensive care units in 18 countries. Hospital mortality was 11% (n = 139), 44% (n = 536) were extubated by HD7 of which 20% (107/536) required reintubation, 28% (n = 340) underwent tracheostomy placement, and 9% (n = 114) developed ARDS. The median MP on HD1, HD3, and HD7 was 11.9 J/min [IQR 9.2-15.1], 13 J/min [IQR 10-17], and 14 J/min [IQR 11-20], respectively. MP was overall higher in patients with ARDS, especially those with higher ARDS severity. After controlling for same-day pressure of arterial oxygen/fraction of inspired oxygen (P/F ratio), BMI, and neurological severity, MP at HD1, HD3, and HD7 was independently associated with hospital mortality, reintubation and tracheostomy placement. The adjusted relative risk (aRR) was greater at higher MP, and strongest for: mortality on HD1 (compared to the HD1 median MP 11.9 J/min, aRR at 17 J/min was 1.22, 95% CI 1.14-1.30) and HD3 (1.38, 95% CI 1.23-1.53), reintubation on HD1 (1.64; 95% CI 1.57-1.72), and tracheostomy on HD7 (1.53; 95%CI 1.18-1.99). MP was associated with the development of moderate-severe ARDS on HD1 (2.07; 95% CI 1.56-2.78) and HD3 (1.76; 95% CI 1.41-2.22).ConclusionsExposure to high MP during the first week of MV is associated with poor clinical outcomes in ABI, independent of P/F ratio and neurological severity. Potential benefits of optimizing ventilator settings to limit MP warrant further investigation
Anti-leishmania antibodies in cerebrospinal fluid from dogs with visceral leishmaniasis
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