A Group Signature Scheme with Easy Membership Canceling

In the group signature scheme with a trusted party, a verifier can determine whether or not a signature is made by a member of the group, but cannot identify the member who signed the signature. In case of dispute later on, the signer can be identified by the trusted party. However, for efficient group signature schemes proposed so far, removing a member from the group can be not efficiently performed. In this paper, a group signature scheme with an easy membership canceling is proposed. By sending a request to use a resource together with the group signature on it to the manager of the resource, the manager can control anonymous accesses to the resource. In such an application, the proposed group signature scheme is suitable for canceling of the access privilege

Toward Security Verification against Inference Attacks on Data Trees

This paper describes our ongoing work on security verification against inference attacks on data trees. We focus on infinite secrecy against inference attacks, which means that attackers cannot narrow down the candidates for the value of the sensitive information to finite by available information to the attackers. Our purpose is to propose a model under which infinite secrecy is decidable. To be specific, we first propose tree transducers which are expressive enough to represent practical queries. Then, in order to represent attackers' knowledge, we propose data tree types such that type inference and inverse type inference on those tree transducers are possible with respect to data tree types, and infiniteness of data tree types is decidable.Comment: In Proceedings TTATT 2013, arXiv:1311.505

Impact of Tax Cuts on the Purchasing Behavior of Low-Pollution Vehicles, Fuel-Efficient Vehicles (Japanese)

This paper focuses on anti-warming measures in the passenger vehicle sector and estimates the impacts of three policies in the green car taxation plan on consumer behavior with respect to car purchases. The three policies refer specifically to, first, preferential taxation for green vehicles; second, special treatment of the vehicle acquisition tax when acquiring fuel-efficient vehicles; and third, special treatment of the vehicle acquisition tax when acquiring low-pollution vehicles. Our estimates are based on fiscal 2004 data, following the introduction of these policies. According to our findings, as far as the effect of the change in pricing structure alone is concerned, the policies contributed slightly to the objective of promoting motor vehicles with less harmful impact on the environment. However, the tax cuts lower the purchase cost and thus create incentives for consumers who otherwise might not purchase these vehicles without such tax cuts. Accordingly, such policies could be contributing to carbon dioxide emissions. Even so, our study has also revealed that the impacts themselves are limited, given that the ratio of tax abatements to total vehicle cost is limited. As a hypothetical policy, our study simulates a package in which the tax cut rate for hybrid vehicles is expanded considerably and the reduction in vehicle acquisition tax on gasoline-powered vehicles is abolished, to reduce the price disparity between the two types of vehicles. This suggests that to ensure that tax cuts have an effect, it is necessary to, first, make a very substantial tax cut for hybrid vehicles and to, second, terminate tax cuts for gasoline powered vehicles, for the purposes of ensuring that the cuts do not motivate consumers who would otherwise not buy a car to purchase a vehicle and narrowing the price gap between gasoline powered and hybrid vehicles.

Drinking, Texting, or Getting Old : Which One is the Most Dangerous While Driving?

The causes of car accidents can be attributed to the types of driving: e.g., impaired, distracted, and cognitively declined. This study attempts to measure the risk of drinking, texting, and aging while driving. Drinking has been a major factor in causing serious accidents and there is a growing concern with the other two types. We find that drink driving is the riskiest among these three types; it is at least three times more dangerous than sober driving. However, texting and aging are also more than 2.6 times more dangerous. This suggests that similar stringent regulations for these types of driving are required and the need for advanced safety systems such as automatic brakes is urgent

Constructions of Generalized Concatenated Codes and Their Trellis-Based Decoding Complexity

In this correspondence, constructions of generalized concatenated (GC) codes with good rates and distances are presented. Some of the proposed GC codes have simpler trellis omplexity than Euclidean geometry (EG), Reed–Muller (RM), or Bose–Chaudhuri–Hocquenghem (BCH) codes of approximately the same rates and minimum distances, and in addition can be decoded with trellis-based multistage decoding up to their minimum distances. Several codes of the same length, dimension, and minimum distance as the best linear codes known are constructed

Uncorrectable Errors of Weight Half the Minimum Distance for Binary Linear Codes

A lower bound on the number of uncorrectable errors of weight half the minimum distance is derived for binary linear codes satisfying some condition. The condition is satisfied by some primitive BCH codes, extended primitive BCH codes, Reed-Muller codes, and random linear codes. The bound asymptotically coincides with the corresponding upper bound for Reed-Muller codes and random linear codes. By generalizing the idea of the lower bound, a lower bound on the number of uncorrectable errors for weights larger than half the minimum distance is also obtained, but the generalized lower bound is weak for large weights. The monotone error structure and its related notion larger half and trial set, which are introduced by Helleseth, Kl{\o}ve, and Levenshtein, are mainly used to derive the bounds.Comment: 5 pages, to appear in ISIT 200

Structural Analysis of Minimum Weight Codewords of the (32, 21, 6) and (64, 45, 8) Extended BCH Codes Using Invariance Property

Two typical examples, the (32, 21, 6) and (64, 45, 8) extended code of primitive permuted BCH codes, are considered. The sets of minimum weight codewords are analyzed in terms of Boolean polynomial representation. They are classied by using their split weight structure with respect to the left and right half trellis sections, and for each class, the standard form is presented. Based on the results, we can generate a proper list of the minimum weight codewords of the codes

Realistic rainbow rendering considering light attenuation due to scattering and absorption in the atmosphere

情報処理学会 グラフィクスとCAD研究会 第134回研究発表会 発表資料 ; 開催場所:NHK放送技術研究所, 東京 ; 開催日:2009年2月16-17