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Fuzzy vector signature (FVS) is a new primitive where a fuzzy (biometric) data w is used to generate a verification key (VKw), and, later, a distinct fuzzy (biometric) data w&prime, (as well as a message) is used to generate a signature (&sigma, w&prime, ). The primary feature of FVS is that the signature (&sigma, ) can be verified under the verification key (VKw) only if w is close to w&prime, in a certain predefined distance. Recently, Seo et al. proposed an FVS scheme that was constructed (loosely) using a subset-based sampling method to reduce the size of helper data. However, their construction fails to provide the reusability property that requires that no adversary gains the information on fuzzy (biometric) data even if multiple verification keys and relevant signatures of a single user, which are all generated with correlated fuzzy (biometric) data, are exposed to the adversary. In this paper, we propose an improved FVS scheme which is proven to be reusable with respect to arbitrary correlated fuzzy (biometric) inputs. Our efficiency improvement is achieved by strictly applying the subset-based sampling method used before to build a fuzzy extractor by Canetti et al. and by slightly modifying the structure of the verification key. Our FVS scheme can still tolerate sub-linear error rates of input sources and also reduce the signing cost of a user by about half of the original FVS scheme. Finally, we present authentication protocols based on fuzzy extractor and FVS scheme and give performance comparison between them in terms of computation and transmission costs.

Fuzzy authentication uses non-deterministic or noisy data, like biometrics, as an authentication factor. Although the data is extracted from the same individual or source, it can be different for each measurement. As a result, one of the main issues in fuzzy authentication is the effective processing of the fuzziness, while guaranteeing the privacy of the fuzzy data. Biometric data is a typical user-generated fuzzy data and the fuzzy extractor is one of the most promising primitives for biometric authentication these days. In 2016, Canetti et al. proposed the reusable fuzzy extractor, in which multiple keys can be generated with the same biometric data. It can also handle some outliers which occur unexpectedly (owing to an external interference when acquiring the fuzzy data, for example, the presence of dust on a fingerprint image). However, the size of the user's helper data in the reusable fuzzy extractor is quite large. This makes the network bandwidth usage required in the online authentication phase (or the storage required on the user side) considerable, which inconveniences the user. In this paper, we present a new primitive for fuzzy authentication, called a fuzzy vector signature (FVS) scheme, which significantly alleviates the burden on the user side. This means that the network bandwidth usage (or the amount of storage required on the user side) is significantly reduced. The proposed FVS scheme is reusable and robust to outliers as well. Finally, we provide a privacy-preserving fuzzy authentication protocol based on the FVS scheme.

We report the barium zirconate supported NiOx catalysts (NiOx/BZO) for dry reforming of methane and feasibility test for their industrial application by using temperature-regulated chemical vapor deposition together with extrusion. Nickel oxide nanoparticles are well deposited and dispersed on BZO powders as well as structures in a gear form, showing high catalytic activity and extraordinary stability even at relatively lower temperature and higher space velocity. The NiOx/BZO catalyst are highly coke resistant for 50 h operation with almost negligible agglomeration of NiOx nanoparticles. Judging from XPS and high ion conducting properties of BZO supports, the –OH or –O species are expected to play an important role in promoting the self-decoking of surface carbon species to form CO and CO2.

A batch-type and lab-scale germanium recovery method was developed via a hybrid approach combining pyro– and hydrometallurgical reactions to prove the feasibility of mass production and economic recovery of germanium from waste optical fibers. More specifically, the extent of pyro-metallurgical separation reaction was carefully examined to determine by trial and error its completion time which was 2 h at 700 °C. The post pyro-metallurgical reaction product was leached at 50, 65, and 80 °C for a maximum 8 hr retention at each temperature, using an optimized composition of aqueous HCl solution: maximum germanium recovery of 26 ppm was thus experimentally substantiated by using the ICP-OES method. XRF analysis was performed on the post-hydrometallurgical leaching residue to detect any significant composition of remaining Ge: The confirmation of Si, Cl, and Na as sole residual elements thus cogently substantiated the complete separation of germanium in accordance with the present hybrid approach. The...

We have synthesized three types of polymers: carbazole (P1), norharmane (P2), and carbazole and harmane copolymer (P3). The optical properties and photophysical properties of these polymers...

International audience; In this study, we propose a new method for conversion from a one-way (OW)-secure key encapsulation mechanism (KEM) into a chosen-ciphertext (CCA) secure KEM in the random oracle model. Our conversion method is based on the non-interactive zero-knowledge (NIZK) proof system for proving the relationships (e.g., equality or linearity) of discrete logarithms, where the security analysis of our conversion method depends on the NIZK properties of soundness and zero-knowledge. Our conversion method achieves tight security reduction and it is semi-generic in the sense that other than OW-security, a KEM should be NIZK-compatible. From a theoretical viewpoint, our conversion method can be considered as the corresponding approach for obtaining an efficient signature by applying the Fiat–Shamir transform to the NIZK system. We applied our conversion method to several OW-secure (identity-based) KEMs and compared the results with those obtained by previous methods for achieving CCA security.

Methanol fuel cells having advantages of relatively favorable reaction kinetics and higher energy density have attracted increasing interests as best alternative to hydrogen fuel cell because of H2 production, storage and distribution issues. While there have been extensive research works on developing key components such as electrocatalysts as well as their physicochemical properties in practical formic acid fuel cells, there have also been urgent requests for investigating which fuel sources will be more suitable for direct liquid fuel cells in future. In this mini-review, we highlight the overall interest and outlook of formic acid fuel cells in terms of electrocatalysts, fuel supply and crossover, water management, fuel cell efficiency and system integration in comparison with methanol fuel cells.

Biometric authentication is considered as being an efficient authentication method, since a user is not required to possess or memorize any other information other than biometrics. However, since biometric information is sensitive and could be permanently unavailable in case of revealing that information just once, it is essential to preserve privacy of biometrics. In addition, since noise is inherent in the user of biometric recognition technologies, the biometric authentication needs to handle the noise. Recently, biometric authentication protocols using fuzzy extractor have been actively researched, but the fuzzy extractor-based authentication has a problem that a user should memorize an additional information, called helper data, to deal with their noisy biometric information. In this paper, we propose a novel biometric authentication protocol using Hidden Vector Key Encapsulation Mechanism(HV-KEM) which is one of functional encryption schemes. A primary advantage of our protocol is that a user does not need to possess or memorize any additional information. We propose security requirements of HV-KEM necessary for constructing biometric authentication protocols, and analyze our proposed protocol in terms of correctness, security, and efficiency.

We develop advanced oxidation processes for the treatment of spent electroless nickel plating solution. Apart form recovering nickel by leaching and enrichment, more emphasis is placed on rendering the waste water recyclable via oxidizing phosphite and hypophosphite into phosphate which can then be precipitated easily. UV/H2O2 process is employed and the conversion efficiency of COD and PO4-P, and H2O2 consumption are analyzed. Furthermore, the UV/H2O2 process in conjunction with O3 generator enables us to not only save the treatment time by 6 hours but also reduce H2O2 consumption by 30%.

Passive keyless entry and start system has been widely used in modern cars. Car owners can open the door or start the engine merely by having the key in their pocket. PKES was originally designed to establish a communication channel between the car and its key within approximately one meter. However, the channel is vulnerable to relay attacks by which attackers unlock the door even if the key is out of range. Even though relay attacks have been recognized as a potential threat for over ten years, such attacks were thought to be impractical due to highly expensive equipment; however, the required cost is gradually practical. Recently, a relay attack has been demonstrated with equipment being sold only under $100. In this paper, we propose a sound-based proximity-detection method to prevent relay attacks on PKES systems. The sound is eligible to be applied to PKES because audio systems are commonly available in cars. We evaluate our method, considering environments where cars are commonly parked, and present the recording time satisfying both usability and security. In addition, we newly define an advanced attack, called the record-and-playback attack, for sound-based proximity detection, demonstrating that our method is robust to such an attack.

We examined and compared the feasibility of vegetable oils with synthetic thermal conductive oils to recover highly purified copper metal from waste jelly-filled communication cables. While polydimethylsiloxane shows relatively poor separation efficiency under entire operating conditions, dibenzyltoluene and waste vegetable oil show the high separation efficiency if the appropriate operating temperature and time were given. By running 50 kg-class equipment with waste vegetable oils, we obtained 100% copper metal recovery with 99.2% purity at 300 °C for 60 min.

Cement kiln dust (CKD) is a major by-product of cement manufacturing and has the potential to be recycled as a raw material if the high concentrations of chlorine and potassium are removed. This study tested four leaching solutions (distilled water and three organic acids) and determined the optimum reaction conditions. At a liquid/solid (L/S ratio) of 10, the removal efficiency of formic, citric, and oxalic acid was higher than that of distilled water, but at L/S 20, distilled water also achieved a high removal efficiency of Cl (&ge, 90%) and K (&ge, 70%). In addition, to minimize the discharge of wastewater after leaching, the efficiency of ion-exchange resins for the recovery of leaching solution was tested. When the cation- and anion-exchange resins were arranged together, more than 95% of both Cl and K contained in the leaching solution could be removed. Leaching solution without Cl and K was found to have a high leaching efficiency even after being recycled three times, resulting in a significant reduction in wastewater emissions.

Mordenite based catalysts for direct decomposition of N2O have been successfully prepared and their direct decomposition performance characterized at the operating temperature of 300–400 °C commonly encountered in the nitric acid plants tail gases. The catalyst was prepared in 2 steps: 1. Precursor wet ion exchange, 2. Precursor impregnation. In addition to the previous contribution, it is shown here that the bimetallic Rh-, Pd-, Ir-Fe-MOR catalysts thus prepared exhibited an excellent N2O decomposition performance: total conversion efficiency of Rh-Fe-MOR catalyst has been achieved at 400 °C and between 7500 h−1 and 10 000 h−1 space velocity.

In this research, the mordenite based catalysts for direct decomposition of N2O have been prepared and characterized for their direct decomposition performance at the operating temperature of 300–550 °C commonly encountered in the nitric acid plants tail gases. The zeolite catalyst was prepared by 2 steps: 1. Precursor wet ion exchange, 2. Precursor impregnation. The bi-metallic catalyst thus prepared shows an excellent N2O decomposition performance. The total conversion efficiency of Pt-Fe-MOR catalyst has been achieved at 390 °C. XPS analysis confirmed platinum on mordenite supports in two forms: PtO and PtO2 species interact with oxygen ions at the metal/support interface. Deposition of Pt as a promoter on the surface of Fe-mordenite results in a considerable enhancement of catalytic activity.