著者

佐々木 悠 王 磊 太田 和夫 青木 和麻呂 國廣 昇

出版者

一般社団法人電子情報通信学会

雑誌

電子情報通信学会ソサイエティ大会講演論文集

巻号頁・発行日

vol.2008, 2008-09-02

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本稿では,MD4を用いたチャレンジ&レスポンス型パスワード認証に対し,現実的な計算量のパスワード復元攻撃を提案する.これらの方式では,ユーザとサーバはパスワードPを事前共有する.認証の手順は以下の通り:1.サーバはチャレンジCを生成しユーザに送る.2.ユーザはレスポンスRとしてResponse(P,C)を計算しサーバに送る.3.サーバは自分でRを計算し,送られてきたRと一致したならば正規ユーザと判定する. 手順2.のRの計算方法として,MD4(P∥C)を用いるPrefix法とMD4(P∥C∥P)を用いるHybrid法が有力である.これらに対する攻撃結果を以下に示す.

著者

江村 超 熊谷 正朗 王 磊 郷古 倫央

出版者

The Society of Instrument and Control Engineers

雑誌

計測自動制御学会論文集 (ISSN:04534654)

巻号頁・発行日

vol.35, no.1, pp.17-23, 1999-01-31 (Released:2009-03-27)

参考文献数

7

被引用文献数

4 1

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Dynamically walking robots require attitude sensors of high resolution and wide-band frequency response. If these characteristics are not good enough, it is difficult to control the robots stably. Rate gyros are widely used attitude sensors in walking robots, but the rate gyro which has both characteristics of sufficiently high resolution and wide-band frequency response is heavy and expensive. Therefore, the authors tried to get a small, light and low-cost rate gyro which has excellent characteristics both in resolution and response frequency by using multiple sensors and subtraction type of filters.In this paper, first, a method to expand response frequency of rate gyros without reducing their resolution and an idea of subtraction type of filters which are useful for expanding frequency range are presented. The subtraction type of filter means the filter that has a transfer function obtained by subtracting another transfer function from 1 (unity). This filter provides flat response after composing two signals whose response frequency ranges are different each other. In this case, one is a signal obtained from a rate gyro whose resolution is high enough but response frequency is low, and the other is a signal obtained from a rate gyro whose resolution is low but response frequency is high enough.If we use an inclinometer together with rate gyros, we can sufficiently decrease zero-drift of gyros, because the inclinometer senses angular displacement by referencing gravity direction and its zero stability is high enough. However, the inclinometer is influenced by horizontal acceleration. This means that we have to use a low-pass filter whose cutoff frequency is extremely low to eliminate signal component induced by horizontal acceleration. Attitude sensor using two rate gyros mentioned above and one inclinometer showed good characteristics concerning zero stability, resolution and response frequency range.

著者

江村 超 熊谷 正朗 王 磊 郷古 倫央

出版者

計測自動制御学会

雑誌

計測自動制御学会論文集 (ISSN:04534654)

巻号頁・発行日

vol.35, no.1, pp.17-23, 1999-01

参考文献数

7

被引用文献数

4

著者

江村 超 熊谷 正朗 王 磊 郷古 倫央

出版者

公益社団法人 計測自動制御学会

雑誌

計測自動制御学会論文集 (ISSN:04534654)

巻号頁・発行日

vol.35, no.1, pp.17-23, 1999

被引用文献数

1

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Dynamically walking robots require attitude sensors of high resolution and wide-band frequency response. If these characteristics are not good enough, it is difficult to control the robots stably. Rate gyros are widely used attitude sensors in walking robots, but the rate gyro which has both characteristics of sufficiently high resolution and wide-band frequency response is heavy and expensive. Therefore, the authors tried to get a small, light and low-cost rate gyro which has excellent characteristics both in resolution and response frequency by using multiple sensors and subtraction type of filters.<br>In this paper, first, a method to expand response frequency of rate gyros without reducing their resolution and an idea of subtraction type of filters which are useful for expanding frequency range are presented. The subtraction type of filter means the filter that has a transfer function obtained by subtracting another transfer function from 1 (unity). This filter provides flat response after composing two signals whose response frequency ranges are different each other. In this case, one is a signal obtained from a rate gyro whose resolution is high enough but response frequency is low, and the other is a signal obtained from a rate gyro whose resolution is low but response frequency is high enough.<br>If we use an inclinometer together with rate gyros, we can sufficiently decrease zero-drift of gyros, because the inclinometer senses angular displacement by referencing gravity direction and its zero stability is high enough. However, the inclinometer is influenced by horizontal acceleration. This means that we have to use a low-pass filter whose cutoff frequency is extremely low to eliminate signal component induced by horizontal acceleration. Attitude sensor using two rate gyros mentioned above and one inclinometer showed good characteristics concerning zero stability, resolution and response frequency range.