Improved Secure and Low Computation Authentication Protocol for Wireless Body Area Network with ECC and 2d Hash Chain

Since technologies have been developing rapidly, Wireless Body Area Network (WBAN) has emerged as a promising technique for healthcare systems. People can monitor patients’ body condition and collect data remotely and continuously by using WBAN with small and compact wearable sensors. These sensors can be located in, on, and around the patient’s body and measure the patient’s health condition. Afterwards sensor nodes send the data via short-range wireless communication techniques to an intermediate node. The WBANs deal with critical health data, therefore, secure communication within the WBAN is important. There are important criteria in designing a security protocol for a WBAN. Sensor nodes in a WBAN have limited computation power, battery capacity, and limited memory. Therefore, there have been many efforts to develop lightweight but secure authentication protocols. In this thesis, a computationally efficient authentication protocol based on Elliptic Curves Cryptography (ECC) and 2D hash chain has been proposed. This protocol can provide high level security and require significantly low computation power on sensor nodes. In addition, a novel key selection algorithm has been proposed to improve efficiency of key usage and reduce computation cost. For this protocol, ECC is used for key exchange and key encryption. The scheme encrypts a key with ECC to create a pair of points and uses this pair of points as keys for an intermediate node and sensor nodes. 2D hash chain technique is used for generating 2D key pool for authentication procedure. This technique can generate many keys efficiently and effectively with hash functions. For security part, this protocol provides essential security features including mutual authentication, perfect forward security, session key establishment, and etc., while providing high level security. In experimental results, this protocol reduced sensor nodes’ computation cost significantly by using combination of ECC and 2D hash chain. Moreover, the computation cost on the intermediate node has been reduced to 48.2% of the existing approach by the new key selection algorithm at an initial authentication. After the initial authentication, the intermediate node’s computation cost is further reduced to 47.1% of the initial authentication by eliminating synchronization phase. In addition, communication cost which is the total packet size of all messages is 1280-bits, which is 5392-bits smaller than the existing approach, for entire authentication and after the initial authentication the cost is reduced to 768-bits

仏教儀式・散華からみたジュエリーの造形研究 [要旨]

東京藝術大学平成28年

Enhanced magnetic and thermoelectric properties in epitaxial polycrystalline SrRuO3 thin film

Transition metal oxide thin films show versatile electrical, magnetic, and thermal properties which can be tailored by deliberately introducing macroscopic grain boundaries via polycrystalline solids. In this study, we focus on the modification of the magnetic and thermal transport properties by fabricating single- and polycrystalline epitaxial SrRuO3 thin films using pulsed laser epitaxy. Using epitaxial stabilization technique with atomically flat polycrystalline SrTiO3 substrate, epitaxial polycrystalline SrRuO3 thin film with crystalline quality of each grain comparable to that of single-crystalline counterpart is realized. In particular, alleviated compressive strain near the grain boundaries due to coalescence is evidenced structurally, which induced enhancement of ferromagnetic ordering of the polycrystalline epitaxial thin film. The structural variations associated with the grain boundaries further reduce the thermal conductivity without deteriorating the electronic transport, and lead to enhanced thermoelectric efficiency in the epitaxial polycrystalline thin films, compared with their single-crystalline counterpart.Comment: 24 pages, 5 figure

Enhanced magnetic and thermoelectric properties in epitaxial polycrystalline SrRuO3 thin film

Transition metal oxide thin films show versatile electrical, magnetic, and thermal properties which can be tailored by deliberately introducing macroscopic grain boundaries via polycrystalline solids. In this study, we focus on the modification of the magnetic and thermal transport properties by fabricating single- and polycrystalline epitaxial SrRuO3 thin films using pulsed laser epitaxy. Using epitaxial stabilization technique with atomically flat polycrystalline SrTiO3 substrate, epitaxial polycrystalline SrRuO3 thin film with crystalline quality of each grain comparable to that of single-crystalline counterpart is realized. In particular, alleviated compressive strain near the grain boundaries due to coalescence is evidenced structurally, which induced enhancement of ferromagnetic ordering of the polycrystalline epitaxial thin film. The structural variations associated with the grain boundaries further reduce the thermal conductivity without deteriorating the electronic transport, and lead to enhanced thermoelectric efficiency in the epitaxial polycrystalline thin films, compared with their single-crystalline counterpart.Comment: 24 pages, 5 figure

Enhanced magnetic and thermoelectric properties in epitaxial polycrystalline SrRuO 3 thin films

International audienceTransition metal oxide thin films show versatile electric, magnetic, and thermal properties which can be tailored by deliberately introducing macroscopic grain boundaries via polycrystalline solids. In this study, we focus on the modification of magnetic and thermal transport properties by fabricating single- and polycrystalline epitaxial SrRuO3 thin films using pulsed laser epitaxy. Using the epitaxial stabilization technique with an atomically flat polycrystalline SrTiO3 substrate, an epitaxial polycrystalline SrRuO3 thin film with the crystalline quality of each grain comparable to that of its single-crystalline counterpart is realized. In particular, alleviated compressive strain near the grain boundaries due to coalescence is evidenced structurally, which induced the enhancement of ferromagnetic ordering of the polycrystalline epitaxial thin film. The structural variations associated with the grain boundaries further reduce the thermal conductivity without deteriorating the electronic transport, and lead to an enhanced thermoelectric efficiency in the epitaxial polycrystalline thin films, compared with their single-crystalline counterpart