2002 Fiscal Year Final Research Report Summary
Digital chaos cipher system
| Project/Area Number |
12450155
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
情報通信工学
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| Research Institution | Kyushu University |
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Principal Investigator |
KOHDA Tohru Kyushu University, Graduate School of Information Science and Electrical Engineering, professor, 大学院・システム情報科学研究院, 教授 (20038102)
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| Co-Investigator(Kenkyū-buntansha) |
SAKURAI Koichi Kyushu University, Graduate School of Information Science and Electrical Engineering, professor, 大学院・システム情報科学研究院, 教授 (60264066)
SUGITA Hiroshi Kyushu University, Graduate School of Mathematics, associate professor, 大学院・数理学研究科, 助教授 (50192125)
OOHAMA Yasutada Kyushu University, Graduate School of Information Science and Electrical Engineering, associate professor, 大学院・システム情報科学研究院, 助教授 (20243892)
JITSUMATSU Yutaka Kyushu University, Graduate School of Information Science and Electrical Engineering, research associate, 大学院・システム情報科学研究院, 助手 (60336063)
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| Project Period (FY) |
2000 – 2002
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| Keywords | chaotic sequence / i.i.d. sequence / correlation / stream cipher / elliptic function map |
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| Research Abstract |
A sequence of binary random variables has found significant applications in modern digital communication systems. For such sequences, several kinds of linear feedback shift register sequences have been proposed. It is, however, well known in probability theory that the Bernoulli shift is a fundamental theoretic model of a sequences of independent identically distributed (i.i.d.) binary random variables. After reviewing fundamental subjects of chaotic dynamics, in particular, a close relationship between information sources and Markov chains, we gave the generation method of sequences of i.i.d. binary random variables using chaotic dynamics. Such a generation method is given as a sufficient condition composed of simple symmetric properties for some class of ergodic maps. Furthermore, we gave the applications of such sequences: 1) to running key sequences for stream cipher systems and 2) to a color image communication system through code-division multiple access channels and its extended version, a digital watermarking system. In addition, the performance of spread spectrum codes generated by a Markov chain is theoretically evaluated in asynchronous direct-sequence/code division multiple access systems.
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