Masaki Inamura

Tightly-Secure Identity-Based Structured Aggregate Signature Scheme under the Computational Diffie-Hellman Assumption.

An aggregate signature scheme is a primitive whereby each signer signs an individual document and combines them to compress data size. We propose an aggregate signature scheme which is an extension in two standpoints of structured signatures and ID-based signatures, i.e., we construct an identity-based structured aggregate signature scheme. The proposed scheme is expected to be used with consumer-generated media services. We prove the security of the proposed scheme with tight reduction under the computational Diffie-Hellman (CDH) assumption in the random oracle model. Tight reduction means that the cost of a reduction algorithm is independent of an adversarys capability, i.e., security is not downgraded by the adversarys capability. To the best of our knowledge, no structured signature scheme with tight reduction has been proposed to date because it contains complicated structures that make the reduction inefficient. Note that the security of our scheme captures the switching attack (CCS 2007, Boldyreva et al.) and the re-ordering attack (ISPEC 2007, Shao), which break several famous schemes.

Content Approval Systems with Expansions of a New Pair-Connected-Structured Aggregate Signature Scheme

In this study, the authors propose new aggregate signature schemes with pairing-based cryptography that can describe the pair-connected structure of signers and examples of new content approval systems with these schemes. Existing structured signature schemes are based on multisignature schemes, which are adapted for verification of a structure if all signers sign the same document. However, if each signer wants to sign a document different from those of other signers, another scheme that is based on an aggregate signature scheme is required. To resolve the above problem, a denoted connective signature is generated in this scheme and can be adapted for verification of variant structures with its expansion. In addition, the authors show examples of effective content approval systems, which can be realize with verifying not only who signs but also which division each of signers belongs to. Content Approval Systems with Expansions of a New Pair-Connected-Structured Aggregate Signature Scheme

Evaluation of Handwriting Characteristic for Two-factor Authentication Interface on Touch-pad Panel

Frequencies of user authentication increase and spread of smartphone and tablet advances rapidly in recent years. However, it is a great challenge that password authentication is easy to be attacked and must be solved. We assume authentication, which use touch panel and handwriting as an authentication element in this paper. As far as we know, there have few papers about generating a digital data from handwriting. Therefore, our contribution of this paper is to define handwriting characteristics of a letter that can convert into a digital data and evaluate possibility of the conversion.

Content Protection Scheme to Realize Edit Control Including Diversion Control and Composition Control

We have proposed a copyright protection technology suitable for editable contents, which can control the change, deletion, and addition of partial contents. In this paper, we propose a new scheme that can control the diversion of partial contents to other contents and composition of contents, in addition to control of the change, deletion, and addition of partial contents using digital signatures based on the author’s intention. This scheme realizes edit control between two or more contents, and is effective with Internet contents such as consumer generated media represented by YouTube. We also evaluate the security of our proposed scheme against various attacks.

Content control scheme to realize right succession and edit control

We propose a copyright protection technology suitable for consumer generated media such as You Tube and CLIP. This technology realizes right succession of and edit control by the previous works authors. In this technology, we use a digital signature to confirm the relation between the primary and secondary authors and to determine whether the contents may be edited. We propose to apply this technology to CLIP, which is a software used to operate a pre-set character three-dimensional (3D) model of a three-dimensional computer graphics (3DCG) for creating computer animation. In addition, we provide three security methods for the proposed technologies.

Surveillance camera system balancing privacy protection and effective surveillance image use

Privacy protection has been attracting considerable attention in recent years. Several instances of surveillance video recordings of famous people in public stores being uploaded to the Internet have been reported. Such instances of privacy infringement have become increasingly concerning. A simple solution to this problem is to obscure the facial features of individuals being recorded in surveillance camera systems. However, in some cases where surveillance camera recordings are required, such as criminal investigations, the solution fails. Therefore, we propose a new surveillance camera system that balances the requirements of privacy protection and those of cases in which unobscured images are required. Further, we present the protocol of the proposed system and evaluate the security of the system against attacks.

A LICENSE MANAGEMENT SYSTEM FOR CONTENT SEPARATE DELIVERY OVER P2P NETWORK

We propose a license management system for content separate delivery over P2P network. In trivial content delivery systems, a content file is delivered to a user bound license data within content-key simultaneously. However, a server needs to administer not only user license but also content files, and so servers load is heavy in these systems. In our proposed system, users can obtain a content file not only a content delivery server but also other and can be licensed for the content-key separated content delivery. Therefore, our proposed system is lightweight and scalable. Furthermore, for the purpose to show the feasibility, we have implemented a prototype system. As the result of the evaluation, we show our proposed system is secure and practical.

Anonymous Handover Mechanism for Service Mobility in Heterogeneous Wireless Networks

Various handover technologies for heterogeneous wireless networks have been proposed. Most of these technologies are based on mobile IP technology, which reduces the processing time of handovers, network authentication, and service authentication. However, guaranteeing continuity with real-time services and/or video-on-demand services is difficult, particularly when the processing time is reduced by separating the node and network sides. Cooperative processing is therefore needed between the node and network sides or network and service authentication. Moreover, the handover mechanism must provide anonymity to the users of content distribution services. We propose an anonymous handover mechanism and efficient authentication scheme that divides the content key into two data sets and transmits these data sets to the mobile node by way of two paths. We analyze this handover mechanism in this paper.