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A joint transform correlator has been constructed by a spatial light modulator that uses the electroabsorption effect of GaAs crystal and operates at a high frame rate a TV camera with logarithmic response and a personal computer. In the system, logarithmic values of joint power spectra generated in an optical system were electrically digitized and inverse-Fourier transformed. The system has accomplished the operation of correlation with a throughput time smaller than 10 ms per an input image.

Abstract. Due to the low-cost nature of sensor network nodes, we cannot generally assume the availability of a high-performance CPU and tamperresistant hardware. Firstly, we propose a reliable broadcast message authentication working under the above-mentioned circumstances. The proposed scheme, although based on symmetric cryptographic primitives, is secure against anyone who knew the message authentication key as well as the malicious router nodes in multi-hop networks. The proposed scheme consists of three steps; (i) reliable broadcast of a message, (ii) legitimate acknowledgments from all the nodes in the network, and (iii) disclosure of the message authentication key. Secondly, we propose a way to reduce the amount of the stored information until the disclosure of the key, in which the server transmits the message integrity code of a message before transmitting the message. Finally, we consider the characteristic and the security issues of the proposed schemes.

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