Building Oblivious Transfer on Channel Delays

In the information-theoretic setting, where adversaries have unlimited computational power, the fundamental cryptographic primitive Oblivious Transfer (OT) cannot be securely achieved if the parties are communicating over a clear channel. To preserve secrecy and security, the players have to rely on noise in the communication. Noisy channels are therefore a useful tool to model noise behavior and build protocols implementing OT. This paper explores a source of errors that is inherently present in practically any transmission medium, but has been scarcely studied in this context: delays in the communication. In order to have a model for the delays that is both general and comparable to the channels usually used for OT – such as the Binary Symmetric Channel (BSC) – we introduce a new noisy channel, the Binary Discrete-time Delaying Channel (BDDC). We show that such a channel realistically reproduces real-life communication scenarios where delays are hard to predict and we propose a protocol for achieving oblivious transfer over the BDDC. We analyze the security of our construction in the semi-honest setting, showing that our realization of OT substantially decreases the protocol sensitivity to the user’s knowledge of the channel compared to solutions relying on other channel properties, and is very efficient for wide ranges of delay probabilities. The flexibility and generality of the model opens the way for future implementation in media where delays are a fundamental characteristic

Computational security of quantum encryption

Quantum-mechanical devices have the potential to transform cryptography. Most research in this area has focused either on the information-theoretic advantages of quantum protocols or on the security of classical cryptographic schemes against quantum attacks. In this work, we initiate the study of another relevant topic: the encryption of quantum data in the computational setting. In this direction, we establish quantum versions of several fundamental classical results. First, we develop natural definitions for private-key and public-key encryption schemes for quantum data. We then define notions of semantic security and indistinguishability, and, in analogy with the classical work of Goldwasser and Micali, show that these notions are equivalent. Finally, we construct secure quantum encryption schemes from basic primitives. In particular, we show that quantum-secure one-way functions imply INDCCA1- secure symmetric-key quantum encryption, and that quantumsecure trapdoor one-way permutations imply semantically-secure publickey quantum encryption

Error Analysis In The Electron Temperature Measurements In Tcabr

An analytical method is proposed to evaluate the experimental uncertainty in the electron temperature measurements in the TCABR tokamak. Solving the integral equation resulting from the convolution of two functions, one representing, the scattered light and the other the spectral apparatus function, i.e., the polychromator, an analytical expression for the electron temperature is obtained, from which the uncertainty in the measured value is readily evaluated. The results show that the major contribution to the error comes from the noise in the signal; the uncertainties in the filters parameters do not contribute significantly to the total error.3701 Instituto de Fisica del Plasma (INFIP),Cons. Nac. Invest. Cient. Tec. (CONICET),Comision Nacional de Energia Atomica (CNEA),Agencia Nacional de Promocion Cientifica y Tecnologica (ANPCyT),Centro Latino-Americano de Fisica (CLAF)Ruchko, L.F., (2002) Braz. J. Phys., 32 (1), pp. 57-64Nascimento, I.C., (2005) Nucl. Fusion, 45, p. 796Nascimento, I.C., (2007) Nucl. Fusion, 47, p. 1570Severo, J.H.F., Tsypin, V.S., Galvão, R.M.O., Nascimento, I.C., Tendler, M., Fagundes, A.N., (2002) Braz. J. Phys, 32 (1), pp. 13-19Severo, J.H.F., Nascimento, I.C., Tsypin, V.S., Galvão, R.M.O., (2003) Nucl. Fusion, 43, pp. 1047-1056Severo, J.H.F., (2009) Nucl. Fusion, 49, p. 115026Severo, J.H.F., Nascimento, I.C., Tsypin, V.S., Kuznetov, Yu.K., Saettone, E.A., Vannucci, A., Galvão, R.M.O., Mikhailovskii, A.B., (2004) Phys. Plasma, 11 (2), pp. 846-848Alonso, M.P., Figueiredo, A.C.A., Borges, F.O., Elizondo, J.I., Galvão, R.M.O., Severo, J.H.F., Usuriaga, O.C., Machida, M., (2010) Rev. Sci. Inst., 81, pp. 10D529Severo, J.H.F., Nascimento, I.C., Kuznetov, Yu.K., Tsypin, V.S., Galvão, R.M.O., Tendler, M., (2007) Rev. Sci Inst., 78, p. 043509Alonso, M.P., (2010) J. Phys.: Conf. Series, 227, p. 012027Forrest, M.J., Peacock, N.J., Robinson, D.C., Sannikov, V.V., Wilcock, P.D., (1970) Culham Plasma Physics Laboratory Report CLM-R 107, , AbingdonAnashin, A.M., Gorbunov, E.P., Ivanov, D.P., Lysenko, S.E., Peacock, N.J., Robinson, D.C., Sannikov, V.V., Strelkov, V.S., (1971) Sov. Phys. - JETP, 33, p. 1127Rautian, S.G., (1958) Sov. Phys. Uspekhi, 66 (1), p. 245Alonso, M.P., Figueiredo, A.C.A., Berni, L.A., Varandas, C.A.F., (2008) IEEE Trans. Plasma Sci., 36 (4), p. 1094Sheffield, J., (1975) Plasma Scattering of Electromagnetic Radiation, , New York: Academic pres

Selecting Machine Learning Algorithms Using the Ranking Meta-Learning Approach

In this work, we present the use of Ranking Meta-Learning approaches to ranking and selecting algorithms for problems of time series forecasting and clustering of gene expression data. Given a problem (forecasting or clustering), the Meta-Learning approach provides a ranking of the candidate algorithms, according to the characteristics of the problem’s dataset. The best ranked algorithm can be returned as the selected one. In order to evaluate the Ranking Meta-Learning proposal, prototypes were implemented to rank artificial neural networks models for forecasting financial and economic time series and to rank clustering algorithms in the context of cancer gene expression microarray datasets. The case studies regard experiments to measure the correlation between the suggested rankings of algorithms and the ideal rankings. The results revealed that Meta-Learning was able to suggest more adequate rankings in both domains of application considered