Papers by Masayuki Hanadate
IFIP International Federation for Information Processing, 2004
Reliable electronic commerce systems must offer fairness. In this paper, we propose a fair exchan... more Reliable electronic commerce systems must offer fairness. In this paper, we propose a fair exchange protocol for trading electronic vouchers, which are the representation of rights to claim goods or services. This protocol enables two players to exchange vouchers stored in their smartcards fairly and efficiently. The players can exchange vouchers through a 4-round mutual communication protocol between their smartcards as long as the protocol is performed properly. If the protocol becomes unable to proceed due to misbehavior of the partner or for any other reason, the player that has fallen into the unfair condition (i.e. the player who sent its voucher but didn't receive the desired voucher) can recover fairness by performing a recovery protocol with a trusted third-party. Since the recovery protocol doesn't need the cooperation of the partner, fairness can be recovered without identifying or tracking the partner; one can trade vouchers securely even if the trading partner cannot be identified. 2.1 Electronic voucher An electronic voucher is a digital representation of the right to claim services or goods. In this context, the right is created by the issuer, such as a supplier of merchandise or provider of services, as a promise to the right holder. According to RFC3506[5], a voucher is defined as follows: Electronic voucher Let I be a voucher issuer, H be a voucher holder, and P be the issuer's promise to the right holder. An electronic voucher is defined as the 3-tuple of (I, P, H). Similar to paper tickets and current money, vouchers should be transferable. The voucher holder H can transfer the voucher (I, P, H) to another participant This transfer is represented as the rewriting of the tuple The right lapses from holder H as a result of the transfer. Vouchers must be protected from illegal acts like forgery, alteration, and reproduction. These security requirements are defined as follows:
This paper proposes FlexToken, a new copy prevention scheme for digital rights such as tickets or... more This paper proposes FlexToken, a new copy prevention scheme for digital rights such as tickets or coupons, which are circulated as pieces of paper in the real world. The important feature of this scheme is that digital rights are represented using two separate types of information: the contents and the token of the rights. The token represents the "genuineness" of the contents and distinguishes the genuine digital rights from copies. A token is stored and circulated using tamper-proof devices such as smartcards while the contents can be held in any storage medium. This approach decreases the amount of memory required of the tamper-proof devices. Furthermore, circulating the identity of the right issuer and accredited information, which specifies the tamperproof devices trusted by the issuer, along with a token makes it possible to protect any type of digital right, regardless of the issuer. Keywords: Electronic commerce, smartcard, copy prevention, rights trading, ticket, ...
2021 4th International Conference on Geoinformatics and Data Analysis, 2021
Recently, real-time geometric data retrieval is the key technology for real-time mobility service... more Recently, real-time geometric data retrieval is the key technology for real-time mobility services to extract spatial-temporal data of moving objects (e.g. self-driving car, connected car and people using augmented reality) inside a static area (e.g. roads, residential area). Also, the high-definition map provides the high precise geographic polygon data on the static area. In general, the system of the real-time geometric data retrieval consists in relational database managing geographic polygon data, key-value store managing spatial-temporal data of the moving objects, and points-in-polygon algorithm for the extraction described in above. However, the system to apply high-definition map for geographic polygon data has two problems; First, too much vertices of high-definition map deteriorates the performance of the points-in-polygon algorithm. Secondly, a user cannot give an appropriate search query since the user does not know the exact shape of geographic polygon data stored in S...
Lecture Notes in Computer Science, 2005
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Papers by Masayuki Hanadate