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Le Touquet – Paris-Plage, France

Bernard S.,University of Neuchatel | Proust J.,ENS | Clement F.,University of Neuchatel
Child Development | Year: 2015

Recent studies have demonstrated that young children use past reliability and consensus to endorse object labels. Until now, no study has investigated how children weigh these two cues when they are in conflict. The two experiments reported here were designed to explore whether any initial preference for information provided by a consensual group would be influenced by the group's subsequent unreliability. The results show that 4- and 5-year-old children were more likely to endorse labels provided by an unreliable but consensual group than the labels provided by a reliable dissenter. Six-year-olds displayed the reverse pattern. The article concludes by discussing the methodological implications of the two experiments and the developmental trajectory regarding the way children weigh consensuality versus reliability. © 2015 The Authors. Source


Wee H.,ENS
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

We present new frameworks for constructing public-key encryption schemes satisfying key-dependent message (KDM) security and that yield efficient, universally composable oblivious transfer (OT) protocols via the dual-mode cryptosystem framework of Peikert, Waters and Vaikuntanathan (Crypto 2008).–Our first framework yields a conceptually simple and unified treatment of the KDM-secure schemes of Boneh et al. (Crypto 2008), Brakerski and Goldwasser (Crypto 2010) and Brakerski, Goldwasser and Kalai (TCC 2011) in the single-key setting.–Using our second framework, we obtain new dual-mode cryptosystems based on the d-linear, quadratic residuocity and decisional composite residuocity assumptions. Both of these frameworks build on the notion of smooth projective hashing introduced by Cramer and Shoup (Eurocrypt 2002), with the additional requirement that the hash function is homomorphic, as is the case for all known instantiations. © International Association for Cryptologic Research 2016. Source


Chen Y.,ENS | Nguyen P.Q.,Tsinghua University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

At EUROCRYPT '10, van Dijk et al. presented simple fully-homomorphic encryption (FHE) schemes based on the hardness of approximate integer common divisors problems, which were introduced in 2001 by Howgrave-Graham. There are two versions for these problems: the partial version (PACD) and the general version (GACD). The seemingly easier problem PACD was recently used by Coron et al. at CRYPTO '11 to build a more efficient variant of the FHE scheme by van Dijk et al. We present a new PACD algorithm whose running time is essentially the "square root" of that of exhaustive search, which was the best attack in practice. This allows us to experimentally break the FHE challenges proposed by Coron et al. Our PACD algorithm directly gives rise to a new GACD algorithm, which is exponentially faster than exhaustive search. Interestingly, our main technique can also be applied to other settings, such as noisy factoring and attacking low-exponent RSA. © 2012 International Association for Cryptologic Research. Source


Pointcheval D.,ENS
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Authenticated Key Exchange protocols enable several parties to establish a shared cryptographically strong key over an insecure network using various authentication means, such as strong cryptographic keys or short (i.e., low-entropy) common secrets. The latter example is definitely the most interesting in practice, since no additional device is required, but just a human-memorable password, for authenticating the players. After the seminal work by Bellovin and Merritt, many settings and security notions have been defined, and many protocols have been proposed, in the two-user setting and in the group setting. © 2012 International Association for Cryptologic Research. Source


Wee H.,ENS
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

We present an identity-based encryption (IBE) scheme in composite-order bilinear groups with essentially optimal parameters: the ciphertext overhead and the secret key are one group element each and decryption requires only one pairing. Our scheme achieves adaptive security and anonymity under standard decisional subgroup assumptions as used in Lewko and Waters (TCC’10). Our construction relies on a novel extension to the Déjà Q framework of Chase and Meiklejohn (Eurocrypt’14). © International Association for Cryptologic Research 2016. Source

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