Optimal Colored Threshold Visual Cryptography Schemes

Visual cryptography schemes allow the encoding of a secret image into n shares which are distributed to the participants. The shares are such that only qualified subsets of participants can visually recover the secret image. Usually the secret image consist of black and white pixels. In colored threshold visual cryptography schemes the secret image is composed of pixels taken from a given set of c colors. The pixels expansion and the contrast of a scheme are two measures of the goodness of the scheme. In this paper, we study c-color (k,n)-threshold visual cryptography schemes and provide a characterization of contrast-optimal schemes. More specifically we prove that there exists a contrast-optimal scheme that is a member of a special set of schemes, which we call canonical schemes, and that satisfy strong symmetry properties. Then we use canonical schemes to provide a constructive proof of optimality, with respect to the pixel expansion, of c-color (n,n)-threshold visual cryptography schemes. Finally, we provide constructions of c-color (2,n)-threshold schemes whose pixels expansion improves on previously proposed schemes

Overcoming the Obfuscation of Java Programs by Identifier Renaming

Decompilation is the process of translating object code to source code and is usually the first step towards the reverse-engineering of an application. Many obfuscation techniques and tools have been developed, with the aim of modifying a program, such that its functionalities are preserved, while its understandability is compromised for a human reader or the decompilation is made unsuccessful. Some approaches rely on malicious identifiers renaming, i.e., on the modification of the program identifiers in order to introduce confusion and possibly prevent the decompilation of the code. In this work we introduce a new technique to overcome the obfuscation of Java programs by identifier renaming. Such a technique relies on the intelligent modification of identifiers in Java bytecode. We present a new software tool which implements our technique and allows the processing of an obfuscated program in order to rename the identifiers as required by our technique. Moreover, we show how to use the existing tools to provide a partial implementation of the technique we propose. Finally, we discuss the feasibility of our approach by showing how to contrast the obfuscation techniques based on malicious identifier renaming recently presented in literature

A cryptographic cloud-based approach for the mitigation of the airline cargo cancellation problem

In order to keep in good long-term relationships with their main customers, Airline Cargo companies do not impose any fee for last minute cancellations of shipments. As a result, customers can book the same shipment on several cargo companies. Cargo companies try to balance cancellations by a corresponding volume of overbooking. However, the considerable uncertainty in the number of cancellations does not allow to fine-tune the optimal overbooking level, causing losses. In this work, we show how the deployment of cryptographic techniques, enabling the computation on private information of customers and companies data can improve the overall service chain, allowing for striking and enforcing better agreements. We propose a query system based on proxy re-encryption and show how the relevant information can be extracted, still preserving the privacy of customers\u2019 data. Furthermore, we provide a Game Theoretic model of the use case scenario and show that it allows a more accurate estimate of the cancellation rates. This supports the reduction of the uncertainty and allows to better tune the overbooking level

A Comparative Analysis of Current Cryptocurrencies

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Secure collaborative supply-chain management

The SecureSCM project demonstrates the practical applicability of secure multiparty computation to online business collaboration. A prototype supply-chain management system protects the confidentiality of private data while rapidly adapting to changing business needs

Preparation and properties of copper-oil-based nanofluids

In this study, the lipophilic Cu nanoparticles were synthesized by surface modification method to improve their dispersion stability in hydrophobic organic media. The oil-based nanofluids were prepared with the lipophilic Cu nanoparticles. The transport properties, viscosity, and thermal conductivity of the nanofluids have been measured. The viscosities and thermal conductivities of the nanofluids with the surface-modified nanoparticles have higher values than the base fluids do. The composition has more significant effects on the thermal conductivity than on the viscosity. It is valuable to prepare an appropriate oil-based nanofluid for enhancing the heat-transfer capacity of a hydrophobic system. The effects of adding Cu nanoparticles on the thermal oxidation stability of the fluids were investigated by measuring the hydroperoxide concentration in the Cu/kerosene nanofluids. The hydroperoxide concentrations are observed to be clearly lower in the Cu nanofluids than in their base fluids. Appropriate amounts of metal nanoparticles added in a hydrocarbon fuel can enhance the thermal oxidation stability

Optical spectral signatures of liquids by means of fiber optic technology for product and quality parameter identification

Absorption spectroscopy in the wide 200-1700 nm spectral range is carried out by means of optical fiber instrumentation to achieve a digital mapping of liquids for the prediction of important quality parameters. Extra virgin olive oils from Italy and lubricant oils from turbines with different degrees of degradation were considered as ‘case studies’. The spectral data were processed by means of multivariate analysis so as to obtain a correlation to quality parameters. In practice, the wide range absorption spectra were considered as an optical signature of the liquids from which to extract product quality information. The optical signatures of extra virgin olive oils were used to predict the content of the most important fatty acids. The optical signatures of lubricant oils were used to predict the concentration of the most important parameters for indicating the oil’s degree of degradation, such as TAN, JOAP anti-wear index, and water content