Kensuke Baba

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As pervasive computing environments become popular, RFID devices, such as contactless smart cards and RFID tags, are introduced into our daily life. However, there exists a privacy problem that a third party can trace user's behavior by linking device's ID.The concept of unlinkability, that a third party cannot recognize whether some outputs are from the(More)
This paper focuses on authentication with three types of entities: a user who sends an authentication request, an authentication-server who receives and verifies the request, and a database who supplies the authentication-server with information for verifying the request. This paper presents novel authentication protocols that satisfy the following(More)
Atallah et al. [ACD01] introduced a randomized algorithm for string matching with mismatches, which utilized fast Fourier transformation (FFT) to compute convolution. It estimates the score vector of matches between text string and a pattern string, i.e. the vector obtained when the pattern is slid along the text, and the number of matches is counted for(More)
The typed λµ-calculus is known to be strongly normalizing and weakly Church-Rosser, and hence becomes confluent. In fact, Parigot formulated a parallel reduction to prove confluence of the typed λµ-calculus by " Tait-and-Martin-Löf " method. However, the diamond property does not hold for his parallel reduction. The confluence for type-free λµ-calculus(More)
This paper proposes a door access control system with mobile phones which allows off-line delegations of an access. A model of door access control with mobile phones is introduced, and then the delegation is formalized as a copy of a door-key. On the previous model, secure copy by off-line is realized using the essential idea of the proxy signature.(More)
Since Grin's work in 1990, classical logic has been an attractive target for extracting computational contents. However, the classical principle used in Grin's type system is the double-negation-elimination rule, which prevents one to analyze the intuitionistic part and the purely classical part separately. By formulating a calculus with J (for the(More)