166 research outputs found
LâHistoire de la peinture en Italie : un sanctuaire pour lâheureux petit nombre
In the Histoire de la peinture en Italie (1817), Stendhal does not describe the paintings. He depreciates the formal aspect of the art of painting because he assigns to it a symbolic fonction : painting is constructed spirituality. To speak about painting is to educate the readerâs sensibility in order for him to create a bond of sympathy with the soul of the artist and of his figures. Painting becomes a sanctuary. To keep away the non believers, Stendhal elaborates a encrypted writing intended for the happy few
Malignité du christianisme. Le Jugement dernier de Michel-Ange dans l'Histoire de la Peinture en Italie de Stendhal
L\u27analyse stendhalienne des tableaux du quinziÚme siÚcle dissimule un violent pamphlet contre l\u27Eglise catholique, et propose une esthétique romantique concurrente de celle du Génie du christianisme de Chateaubriand
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
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
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.
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
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)
Anonymous Traitor Tracing: How to Embed Arbitrary Information in a Key
In a traitor tracing scheme, each user is given a different decryption key. A content distributor can encrypt digital content using a public encryption key and each user in the system can decrypt it using her decryption key. Even if a coalition of users combines their decryption keys and constructs some ``pirate decoder\u27\u27 that is capable of decrypting the content, there is a public tracing algorithm that is guaranteed to recover the identity of at least one of the users in the coalition given black-box access to such decoder.
In prior solutions, the users are indexed by numbers and the tracing algorithm recovers the index of a user in a coalition. Such solutions implicitly require the content distributor to keep a record that associates each index with the actual identifying information for the corresponding user (e.g., name, address, etc.) in order to ensure accountability. In this work, we construct traitor tracing schemes where all of the identifying information about the user can be embedded directly into the user\u27s key and recovered by the tracing algorithm. In particular, the content distributor does not need to separately store any records about the users of the system, and honest users can even remain anonymous to the content distributor.
The main technical difficulty comes in designing tracing algorithms that can handle an exponentially large universe of possible identities, rather than just a polynomial set of indices . We solve this by abstracting out an interesting algorithmic problem that has surprising connections with seemingly unrelated areas in cryptography. We also extend our solution to a full ``broadcast-trace-and-revoke\u27\u27 scheme in which the traced users can subsequently be revoked from the system. Depending on parameters, some of our schemes can be based only on the existence of public-key encryption while others rely on indistinguishability obfuscation
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