エスパアンテナを用いた無線秘密鍵共有方式における干渉信号送信に基づく盗聴耐性向上法

摘要

As a countermeasure scheme against an eavesdropper in wireless communications, a key agreement scheme using an ESPAR antenna has been proposed. In this method, there exist some positions where correlation of the RSSI (Received Signal Strength Indicator) profiles between the intended receiver and the eavesdropper is considerably high when it is evaluated in an indoor environment without obstacles. There remains a danger that the private key is estimated by the eavesdropper at such a position. To improve the wiretapping tolerance, this paper proposes a new private key agreement system using interference transmission. The interference signals are transmitted with weighting factors by which the interference is canceled at the intended receiver position. The performance of the proposed system is evaluated by computer simulations and it is shown that the correlation of the RSSI profiles is successfully decreased by the proposed system.%無線通信の盗聴対策として，エスパアンテナを用いた秘密鍵共有方式が提案されている．この方式で は，障害物の無い室内環境で正親局と盗聴局とのRSSI（受信信号強度）履歴の相関が高くなる位置が存在し，そのような位置において盗聴局に秘密鍵を推定される危険性があった．そこで本稿では，この方式の盗聴耐性の向上を目的とし，正規受信局の位置でキャンセルされるように制御された干渉信号をRSSI測定用信号と同時に送信する秘密鍵共有システムを提案する．計算機シミュレーションにより，提案方式がRSSI 履歴の相関を低減できることを示す．