Hideichi Sasaoka

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We describe a secure communication scheme that uses the random fluctuation of the natural environment of communication channels. Only the transmitter and the receiver share the communication channel characteristics. From reciprocity between a transmitter and a receiver, it is possible for them to share one-time information of their fluctuating channel. This(More)
We consider secret key agreement based on radio propagation characteristics in a two-way relaying system where two legitimate parties named Alice and Bob communicate with each other via a trusted relay. In this system, Alice and Bob share secret keys generated from measured radio propagation characteristics with the help of the relay in the presence of an(More)
As a countermeasure for eavesdroppers in wireless communication, a secret key agreement scheme using a variable directional antenna named ESPAR antenna was developed. In this paper, we describe an improved key generation method using multi-level quantization and parity check in the secret key agreement scheme. It enhances key agreement probability in(More)
In recent years, the multiple-input multiple-output (MIMO) interference channels, where multiple pairs of a transmitter and a receiver having multiple antennas communicate in parallel, have been considered to maximize transmission capacity in a multiple communication environment. In that case, Interference Alignment (IA) is a promising candidate technology(More)
近年の無線通信の普及に伴い,無線通信のセキュリ ティ対策が重要となっている.無線通信における盗聴 対策としては,共通鍵暗号方式を用いて暗号通信を行 うことが一般的である.共通鍵暗号方式は,第三者に は秘密の情報(以下,秘密情報と呼ぶ)に対して,送 信局と受信局で同じ秘密鍵を用いて暗号化と復号を行 う方式で,暗号化した情報を伝送することで秘密情報 の安全性を保つことができる.この方式は,秘密通信 が容易であるという利点がある一方で,秘密鍵を第三 者に知られないように共有し,管理する必要がある. 秘密鍵の共有手法として,現在は公開鍵暗号方式を用 いた秘密鍵の直接配送により共有することが一般的で あるが,公開鍵暗号方式は計算量の複雑性に基づく方 式であるため,消費電力に制限のある移動通信に適用(More)
In this paper, an energy detection scheme based on the pseudo bit error rate (BER) estimation is investigated. In the proposed scheme, the basic strategy is to use the pseudo BER to estimate the signal-noise-ratio (SNR) of primary signal for energy detection at the cognitive users. Threshold and sensing length are updated with the estimated SNR afterward.(More)
We consider information reconciliation in secret key agreement from a fading channel where two legitimate parties utilize channel estimates of their fading channel as correlated random variables to generate a secret key. The information reconciliation is a process of correcting the discrepancies between the legitimate parties' keys by public discussion in(More)
This paper considers the problem of wireless secret key agreement based on radio propagation characteristics, where two legitimate parties generate and share a secret key by exploiting the radio propagation characteristics between them in the presence of an eavesdropper. We developed an experimental system using array antennas to implement the wireless(More)