This paper improves the performance of the revised-simplified verifiable re-encryption mixnet (R-SVRM) based e-voting scheme by introducing confirmation numbers (CNs) that are used in the CN based e-voting scheme. Although CN based and R-SVRM based schemes had made e-voting schemes more practical by excluding zero knowledge proof (ZKP) that requires large volume of computations, still they are not efficient enough. Namely, the CN based scheme adopts RSA encryption functions that are not probabilistic or commutative, therefore to satisfy essential requirements of elections, extra random factors are necessary for individual votes, election authorities must sign on votes and they must keep encryption keys as their secrets. On the other hand, although the R-SVRM based scheme uses ElGamal encryption functions that are probabilistic and commutative, vote forms in it is complicated, i.e., vote forms consist of at least 3 items and they include information about candidates as exponents. The improved scheme simplifies vote forms by exploiting CNs, and extensively reduces the number of operations required for individual votes. Also, the scheme successfully satisfies all essential requirements of e-voting systems, i.e., it is endowed with features about privacy, robustness, accuracy, incoercibility and fairness as CN based and R-SVRM based schemes are.

Off-line anonymous credit card systems are ones that enable card holders to make purchases anonymously while being disconnected from a card company, i.e. without using information maintained the by card company or other shops. This paper proposes one of components that are required for developing off-line anonymous credit card systems. The proposed component enables card holders to protect their tokens from being used by other entities.

An optimal resource allocation algorithm, Hungarian algorithm, is not directly applicable to manufacturing scheduling problems, because solutions of resource allocation problems may violate precedence constraints among processes that constitute individual manufacturing jobs. To apply Hungarian algorithm to scheduling problems, in this paper, several strategies for assigning prices to time slots of individual machines, which are allocated to processes, are proposed. Preliminary experimentation results showed that these strategies can generate near optimal schedules, i.e. when lengths of scheduling horizons were larger than 3 times of the maximum lengths of jobs, generated schedules could complete given jobs while maintaining the deterioration of the efficiency less than 5% from optimal schedules.

This paper discusses mechanisms to identify dishonest users of services provided by a server in environments where identities of honest users must be kept as their secrets. An anonymous token based mechanism enables the server to identify dishonest users when dishonest events are detected while the users are receiving services, and a homomorhic anonymous token based one enables that even dishonest events can be detected only after the server completed their services and the users had left from the server. A linear equation based encryption algorithm that is used for implementing the above methods is also enhanced.

This paper proposes a new electronic voting (e-voting) scheme that fulfills all the security requirements of e-voting. The key mechanism is the one that uses confirmation numbers involved in individual votes to make votes verifiable while disabling all entities including voters themselves to know the linkages between voters and their votes. Unlike complicated zero knowledge proof involved in many e-voting schemes, the confirmation numbers attain the verifiability requirement in a much more simple and intuitive way, then the scheme becomes scalable and practical.

Anonymous networks enable entities to send messages without disclosing their identities. Many anonymous networks had been proposed already, such as Mixnet, DC-net, Crowds, etc. However, they still have serious drawbacks. Namely, they require tremendous computation overheads to transmit messages over networks. That is because asymmetric key encryption algorithms are used. This paper proposes a new mechanism for anonymous communication that removes these drawbacks while exploiting symmetric key encryption algorithms.

This paper proposes a new mechanism for anonymous communication to promote recycling of goods. It can be considered that one of the major barriers that makes people reluctant to exchange their goods is the traceability of people who sell or buy goods to be recycled. In terms of this traceability the current Internet is not suitable, when it is used as a communication platform for exchanging products to be recycled, i.e. identities of message senders can be disclosed easily by tracing message paths back to their senders. Although many anonymous network mechanisms had been proposed already, such as mix-net, DC-net, crowds and so on, they still have drawbacks. The proposed mechanism remove these drawbacks.

Recycling is one of the most important solutions for reducing material and energy consumption, and that of end products is considered as the most effective one. To promote recycling of end products, this paper discusses the requirements for information systems, in which people exchange their owning end products through auctions, while assuming that the major barrier for people to participate these auctions is that people who sell or buy products to be recycled are traceable. It is also shown that these requirements can be satisfied by the state of the art technologies.

Anonymous credit card systems are ones, in which credit card holders can conceal individual transactions from card companies, while enabling card companies to calculate total expenditures of individual cardholders. Although an already proposed mechanism enables card companies also to detect dishonest transaction records, some of them are detected at the end of service periods, and losses caused by this detection delay may grow large to tolerate. To minimize risks caused by dishonest transactions, this paper proposes a mechanism to detect every dishonest transaction record at its occurrence time, and to limit total expenditures of individual cardholders while maintaining anonymity of their transactions.

This paper proposes a path-planning algorithm for multi-arm manipulators that calculates paths by searching grid points in Euclidean space directly instead of configuration space. The algorithm is back track free and resolution complete. Different from existing resolution complete algorithms, its computation time and memory space are proportional to the number of arms. Therefore paths can be calculated within practical time even for manipulators with many arms, and it becomes possible to apply it to manipulators that operate in complicated and fully automated environments. Effectiveness of the algorithm is evaluated by applying a preliminary prototype to path-planning in 2-dimensional space.