Secure Multi-Party Computation without Agreement

It has recently been shown that authenticated Byzantine agreement, in which more than a third of the parties are corrupted, cannot be securely realized under concurrent or parallel (stateless) composition. This result puts into question any usage of authenticated Byzantine agreement in a setting where many executions take place. In particular, this is true for the whole body of work of secure multi-party protocols in the case that a third or more of the parties are corrupted. This is because these protocols strongly rely on the extensive use of a broadcast channel, which is in turn realized using authenticated Byzantine agreement. We remark that it was accepted folklore that the use of a broadcast channel (or authenticated Byzantine agreement) is actually essential for achieving meaningful secure multi-party computation whenever a third or more of the parties are corrupted. In this paper we show that this folklore is false. We present a mild relaxation of the definition of secure computation allowing abort. Our new definition captures all the central security issues of secure computation, including privacy, correctness and independence of inputs. However, the novelty of the definition is in decoupling the issue of agreement from these issues. We then show that this relaxation suffices for achieving secure computation in a point-to-point network. That is, we show that secure multi-party computation for this definition can be achieved for any number of corrupted parties and without a broadcast channel (or trusted pre-processing phase as required for running authenticated Byzantine agreement). Furthermore, this is achieved by just replacing the broadcast channel in known protocols with a very simple and efficient echo-broadcast protocol. An important corollary of our result is the ability to obtain multi-party protocols that remain secure under composition, without assuming a broadcast channel.     

Fast Cut-and-Choose-Based Protocols for Malicious and Covert Adversaries

In the setting of secure two-party computation, two parties wish to securely compute a joint function of their private inputs, while revealing only the output. One of the primary techniques for achieving efficient secure two-party computation is that of Yao’s garbled circuits (FOCS 1986). In the semi-honest model, where just one garbled circuit is constructed and evaluated, Yao’s protocol has proven itself to be very efficient. However, a malicious adversary who constructs the garbled circuit may construct a garbling of a different circuit computing a different function, and this cannot be detected (due to the garbling). In order to solve this problem, many circuits are sent and some of them are opened to check that they are correct while the others are evaluated. This methodology, called cut-and-choose, introduces significant overhead, both in computation and in communication, and is mainly due to the number of circuits that must be used in order to prevent cheating. In this paper, we present a cut-and-choose protocol for secure computation based on garbled circuits, with security in the presence of malicious adversaries, that vastly improves on all previous protocols of this type. Concretely, for a cheating probability of at most \(2^{-40}\), the best previous works send between 125 and 128 circuits. In contrast, in our protocol 40 circuits alone suffice (with some additional overhead). Asymptotically, we achieve a cheating probability of \(2^{-s}\) where \(s\) is the number of garbled circuits, in contrast to the previous best of \(2^{-0.32s}\). We achieve this by introducing a new cut-and-choose methodology with the property that in order to cheat, all of the evaluated circuits must be incorrect, and not just the majority as in previous works. The security of our protocol relies on the decisional Diffie–Hellman assumption.     

Film thickness in horizontal annular flow

Film thickness in horizontal annular flow in small diameter pipes (8-12 mm) was measured as a function of circumferential position. In addition a simple analytical model for the prediction of the film thickness at the top and bottom of the pipe is proposed.     

Absorption of a multicomponenet gaseous mixtures in the presence of instantaneous surface reaction

The rate of absorption from a multicomponent gaseous mixture into a flowing stream in the presence of instantaneous surface reaction is investigated. This is effected by using the generalized Fick's Law for multicomponent diffusion and also by applying the approximate approach based on the assumption that the concentrations of the reactive species are small. Constant properties are assumed for the mixture which are taken at a reference state. As an example, the absorption of C0₂-H₂S and C0₂-H₂ from air are considered. The results show that when the binary diffusion coefficients of the species in the inert gas are greatly different, the error introduced in calculations based on the “Low Concentration” approach is quite appreciable.     

Source-model technique analysis of electromagnetic scattering by surface grooves and slits

A computational tool, based on the source-model technique (SMT), for analysis of electromagnetic wave scattering by surface grooves and slits is presented. The idea is to use a superposition of the solution of the unperturbed problem and local corrections in the groove/slit region (the grooves and slits are treated as perturbations). In this manner, the solution is obtained in a much faster way than solving the original problem. The proposed solution is applied to problems of grooves and slits in otherwise planar or periodic surfaces. Grooves and slits of various shapes, both smooth ones as well as ones with edges, empty or filled with dielectric material, are considered. The obtained results are verified against previously published data.     

Amplified multiplexed analysis of DNA by the exonuclease III-catalyzed regeneration of the target DNA in the presence of functionalized semiconductor quantum dots

Quantum dots (QDs) functionalized with a black-hole quencher are used as optical tracer for the detection of DNA using exonuclease as a biocatalyst. The binding of the target DNA or of a target/open hairpin complex to the functionalized QDs leads to the exonuclease-stimulated recycling of the target DNA or the target/hairpin complex. This results in the triggering of the luminescence of the QDs that provides a readout signal for the amplified sensing process. By using different-sized QDs, the multiplexed detection of DNAs is demonstrated.     

Efficiency of destruction of waste used in the co-incineration in the rotary kilns

This work presents a study about the efficiency of destruction of industrial waste, used in the co-incineration in rotary kilns of the cement industry, considering the principle of the chemistry equilibrium and the kinetic of the reactions. As an example, it has analysed the burn of one hazardous waste which has in its composition toluene, xylene and dicloroethane. The temperatures of the transformation and the time of the reaction to the formation of sub-products which will originate CO₂, H₂O and HCl, are evaluated. Thus, the formation of the pollutants in the kiln is preliminary estimated and the different forms to control the emissions is also discussed.