Culture and Social Media

博士(文学)神戸市外国語大

A Survey on Homomorphic Encryption Schemes: Theory and Implementation

Legacy encryption systems depend on sharing a key (public or private) among the peers involved in exchanging an encrypted message. However, this approach poses privacy concerns. Especially with popular cloud services, the control over the privacy of the sensitive data is lost. Even when the keys are not shared, the encrypted material is shared with a third party that does not necessarily need to access the content. Moreover, untrusted servers, providers, and cloud operators can keep identifying elements of users long after users end the relationship with the services. Indeed, Homomorphic Encryption (HE), a special kind of encryption scheme, can address these concerns as it allows any third party to operate on the encrypted data without decrypting it in advance. Although this extremely useful feature of the HE scheme has been known for over 30 years, the first plausible and achievable Fully Homomorphic Encryption (FHE) scheme, which allows any computable function to perform on the encrypted data, was introduced by Craig Gentry in 2009. Even though this was a major achievement, different implementations so far demonstrated that FHE still needs to be improved significantly to be practical on every platform. First, we present the basics of HE and the details of the well-known Partially Homomorphic Encryption (PHE) and Somewhat Homomorphic Encryption (SWHE), which are important pillars of achieving FHE. Then, the main FHE families, which have become the base for the other follow-up FHE schemes are presented. Furthermore, the implementations and recent improvements in Gentry-type FHE schemes are also surveyed. Finally, further research directions are discussed. This survey is intended to give a clear knowledge and foundation to researchers and practitioners interested in knowing, applying, as well as extending the state of the art HE, PHE, SWHE, and FHE systems.Comment: - Updated. (October 6, 2017) - This paper is an early draft of the survey that is being submitted to ACM CSUR and has been uploaded to arXiv for feedback from stakeholder

Novel Approach for Synthesis of Magnesium Borohydride, Mg(BH4)2

AbstractMg(BH4)2 is a complex hydride with one of the highest hydrogen contents (∼ 15%) known yet. Several synthesis routes have been reported for it, all based on the metathesis reaction of MgCl2 with NaBH4 performed in a ball-mill or in suitable solvents.In the present study a new approach for synthesis of Mg(BH4)2 will be presented in which the more reactive MgBr2 is used instead of MgCl2. For this purpose a mixture of MgBr2 and NaBH4 (molar ratio: 1: 2 and 1:2.15) was ball-milled for 6, 12 and 18h, respectively. Mg(BH4)2 was extracted from the reaction product (Mg(BH4)2 + NaBr) by Soxhlet with diethylether over a day. The remaining residue after solvent evaporation was dried in vacuum at 150°C for 24h and 5h at 190°C. The intermediate and final products of the reactions were analyzed using XRD, DTA/TG, Mass and Vibrational Spectroscopy. The XRD diagrams of the mixture after ball milling showed only the characteristic reflections of NaBr and the patterns obtained after solvent extraction was in all cases consistent with β- Mg(BH4)2. The additional weak MgBr2 reflections, decreased by increasing the ball milling time from 6 to 18h. The DTA/TG coupled with MS revealed ∼11% mass loss when the product was heated up to 600°C. The result of MS detected that the exhaust gas is exclusively H2.Compared to MgCl2, the use of MgBr2 has two advantages: the reaction time is considerably shorter and the excess of MgBr2 can act as additive lowering the onset temperature for hydrogen release from 290°C - for pure Mg(BH4)2 - to ∼ 220°C

Reanalysis of Genetic Data and Rethinking Dopamine\u27s Relationship With Creativity

Several genetic analyses of creativity have recently been reported. A key finding is that dopamine might be related to ideational fluency (Runco, Noble, Reiter-Palmon, Acar, Ritchie, & Yurkovich, 2011) or even to creativity per se (Reuter, Roth, Holve, & Hennig, 2006). Previous analyses have ignored an important part of genetic theory, however, namely the likelihood of polygenetic contributions. Many human characteristics are polygenetic

Car seat design to improve rear-impact protection

This study presents car seat concepts which are designed to mitigate whiplash injuries through coordinated motion of seat components for a wide range of crash severities. In order to evaluate the effectiveness of the proposed car seat concepts, computational multibody models of a generic car seat and a biofidelic 50th-percentile male human model for rear impact are developed. A number of car seat concepts are shown to reduce the risk of whiplash injuries by utilizing head restraint support and energy-absorbing features, which remain reusable after impact