Privacy-preserving PKI design based on group signature

Nowadays, Internet becomes a part of our life. We can make use of numerous services with personal computer, Lap-top, tablet, smart phone or smart TV. These devices with network make us enjoy ubiquitous computing life. Sometimes, on-line services request us authentication or identification for access control and authorization, and PKI technology is widely used because of its security. However the possibility of privacy invasion will increase, if We’re identified with same certificate in many services and these identification data are accumulated. For privacy-preserving authentication or anonymous authentication, there have been many researches such as Group signatures, anonymous credentials, etc. Among these researches, group signatures are very practical Because they provide unlinkability and traceability as well as anonymity. In this paper, we propose a privacy-preserving PKI based on group signature, with which users’ privacy can be Kept in services. Because of traceability, their identities can be traced if they abuse anonymity such as cybercrime. Moreover, we will also discuss open issues for further studies

A Solution-Processed Cathode Interfacial Layer Facilitates Efficient Energy Level Alignment in Organic Photovoltaics

We synthesized and used small-molecule cathode interfacial materials in organic photovoltaic devices (OPVs). Two small-molecule interfacial materials with phosphine oxide and benzoimidazole groups induced strong interface dipoles and chelated with the metal electrodes. The molecules can be dissolved in various organic solvents for processing. We used isopropanol (an environmentally benign solvent) to dissolve the small-molecule materials and spin-coated solutions onto photoactive layers. The materials formed ohmic contacts between the electron acceptor PC71 BM and the AI cathodes and facilitated efficient charge carrier extraction at the electrodes of OPVs. Analyses of the material and device properties of the two interfacial materials and the photovoltaic performances of OPVs with the materials revealed that the materials were promising cathode interfacial materials for photovoltaic applications. The interfacial material featuring two benzoimidazole groups optimally formed smooth interfacial layers affording better energy level alignment between the electron acceptors and the cathode.11Nsciescopu

Elucidation of the Formation Mechanism of Highly Oriented Multiphase Ruddlesden-Popper Perovskite Solar Cells

The crystallographic orientation and phase distribution of two-dimensional Ruddlesden-Popper perovskites (2D-RPPs) should be carefully controlled to obtain high-performance 2D-RPP-based opto-electronic devices. However, these characteristics are still unclear. Herein, we systematically examine the formation mechanism of highly oriented multiphase 2D-RPPs. We argue that the 3D-like perovskites containing small organic cations nucleate first with out-of-plane (111) preferential orientation, followed by the further growth of two- dimensional perovskites incorporating bulky organic cations owing to the difference in the solubility between small and bulky cations. This spatial segregation of organic cations across the film depth induces the formation of multiple perovskite phases, which produces n-value-graded 2D-RPP films with continually upshifted band energy alignment. Highly oriented multiphase 2D-RPP films with isobutylammonium (isoBA(2)(Cs(0.02)MA(0.64)FA(0.34))(4)Pb5I6) were successfully employed as a photoabsorbers for perovskite solar cells (PSCs), exhibiting remarkable efficiency of over 16% and significantly enhanced environmental stability compared with their three-dimensional counterparts.11Nsciescopu

Local conductance mapping of water-intercalated graphene on mica

We report that the conductance of graphene is influenced by intercalated water layers using current sensing atomic force microscopy (AFM). We obtained a confined water layer between chemical vapor deposition graphene and mica by transferring graphene onto mica in a liquid water bath. Atomic force microscopy topographic images confirm high coverage by a single water layer, and scanning tunneling microscopy (STM) verifies a clean surface without contamination by measuring the honeycomb lattice structure of the graphene. We show that the surface conductance is perturbed by the presence of a water layer between the graphene and mica, which is not found in the STM topographic image. We found that the graphene on the edge and at pinholes of the water layer exhibits lower conductance, compared with that of graphene on the water terrace. We attribute the perturbation of conductance to structural defects from the water film and a variation of interaction between the edge of the water and graphene. © 2016 Author(s)2

Performance Investigation of Superplastic Shape Memory Alloy-Based Vibration Isolator for X-Band Active Small SAR Satellite of S-STEP under Acoustic and Random Vibration Environments

In a launch environment, all satellites are subjected to severe random vibration and acoustic loads owing to rocket separation, airflow, and injection/combustion of the fuel. Structural vibrations induced by mechanical loads cause the malfunction of vibration-sensitive components in a satellite, leading to failures during the launch process or an on-orbit mission. Therefore, in this study, a shape memory alloy-based vibration isolator was used on the connection between the launch vehicle and satellite to reduce the vibration transmission to a satellite. The vibration isolator exhibited a high performance in the vibration isolation, owing to the dynamic properties of super-elasticity and high damping. The vibration-reduction performance of the vibration isolator was experimentally verified using random vibration and acoustic tests in a structural thermal model of the satellite developed in the synthetic aperture radar technology experimental project. Owing to the super-elasticity and high attenuation characteristics of the vibration isolator, it was possible to significantly reduce the random vibration of the satellite in the launch environment. Although the mechanical load of the acoustic test mainly excited the antenna on the upper side of the satellite rather than the bottom side, the results of the acoustic test showed the same trend as the random vibration test. From this perspective, the vibration isolator can contribute to saving the costs required for satellite development. These advantages have made it possible to develop satellites according to the new space paradigm, which is a trend in the space industry worldwide

Strain-Mediated Phase Stabilization: A New Strategy for Ultrastable alpha-CsPbI3 Perovskite by Nanoconfined Growth

All-inorganic cesium lead triiodide (CsPbI3) perovskite is considered a promising solution-processable semiconductor for highly stable optoelectronic and photovoltaic applications. However, despite its excellent optoelectronic properties, the phase instability of CsPbI3 poses a critical hurdle for practical application. In this study, a novel stain-mediated phase stabilization strategy is demonstrated to significantly enhance the phase stability of cubic a-phase CsPbI3. Careful control of the degree of spatial confinement induced by anodized aluminum oxide (AAO) templates with varying pore sizes leads to effective manipulation of the phase stability of alpha-CsPbI3. The Williamson-Hall method in conjunction with density functional theory calculations clearly confirms that the strain imposed on the perovskite lattice when confined in vertically aligned nanopores can alter the formation energy of the system, stabilizing alpha-CsPbI3 at room temperature. Finally, the CsPbI3 grown inside nanoporous AAO templates exhibits exceptional phase stability over three months under ambient conditions, in which the resulting light-emitting diode reveals a natural red color emission with very narrow bandwidth (full width at half maximum of 33 nm) at 702 nm. The universally applicable template-based stabilization strategy can give in-depth insights on the strain-mediated phase transition mechanism in all-inorganic perovskites.11Nsciescopu