著者

繁富利恵 大塚玲 KeithMartin 今井 秀樹

出版者

一般社団法人情報処理学会

雑誌

情報処理学会研究報告コンピュータセキュリティ(CSEC) (ISSN:09196072)

巻号頁・発行日

vol.2004, no.75, pp.359-366, 2004-07-21

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現状のサービスにおいて、サービス提供者における利用履歴の収集は、よりきめ細やかなサービスを行う上においては、非常に重要な位置を占める。しかし、現状のプライバシ保護の匿名性における研究は、ユーザのlinkabilityを持たない匿名性のみを含んだものが多く、サービス提供者における情報収集を加味している研究が少ない。そこで本稿では、ユーザが認めた場合にのみ、サービス提供者が、匿名性を保ったままlinkabilityをつけることのできる方式について提案を行う。As more service are provided digitally and digital service providers collect more information about users, potential privacy problems are on the increase. This is particularly true when users have to present some form of electronic token in exchange for a digital service. One way to address privacy problems is to provide digital services anonymously. The problem with many previous anonymous token services is that once a token is issued, for a particular value, it cannot be modified in any way other than to decrease the amount of credit associated with the token as it is spent. In this paper we propose a system for "refreshing" tokens anonymously which allows the holder of a token to request that the issuing organization reissues a modified token in an anonymous way. the new (refreshed) token includes the same embedded user identification as the original token. Unlike most previous schemes, this allows anonymous tokens to be used for applications such as foreign exchange, where tokens may need to be exchanged for refreshed tokens issued in a different monetary value. This scheme also allows anybody to check the validity of the token (not just the token)