記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

In digital fingerprinting schemes based on the spread spectrum technique, (quasi-) orthogonal sequences are assigned to users as their fingerprints, and they are embedded into digital contents prior to distribution. Owing to the (quasi-) orthogonality, we can uniquely identify the users from a pirated copy, even if dozens of users are involved in the collusion process. Because the number of users accommodated in a fingerprinting system is generally very large, the interference among the sequences involved in a pirated copy becomes non-negligible as the number of colluders increases. In this paper, we investigate the interference from the viewpoint of a communication channel, and we propose an effective removal operation to reduce the interference as far as possible. By iteratively operating the proposed detector, we can sequentially and successively detect colluders from a pirated copy. Furthermore, two kinds of thresholds are introduced in order to perform the removal operation adaptively for detected signals. Experimental results reveal a drastic improvement in the traceability and a reduction in the amount of interference by the removal operation.

DOI： 10.1109/TIFS.2011.2170421

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

In spread spectrum fingerprinting, it has been considered that the strength of the embedded signal is reduced to of its original value when copies are averaged by colluders. In this study, we analyze the model of the averaging attack by considering quantization that causes nonlinear changes in the fingerprint sequence. Our detailed analysis reveals that the attenuation of the signal energy strongly depends on the quantization performed during the embedding and averaging stages. We estimate the actual attenuation factor from the perspective of a stochastic model in the spatial domain and derive an attenuation factor that differs considerably from the conventional one. Our simulation result indicates that the actual attenuation factor is classified into the best and worst cases from the detector's perspective. Furthermore, we demonstrate that colluders can select the worst case by comparing their fingerprinted copies. A countermeasure for preventing the worst-case scenario is also proposed in this paper.

DOI： 10.1109/TIFS.2010.2082535

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

On the basis of the characteristics of cyclic codes, the codeword space can be partitioned into small subspaces where cyclically shifted codewords of a particular codeword occupy the same subspace. A cyclically permutable code generates codewords belonging to each subspace. However, no approach for the efficient construction of cyclically permutable code from binary cyclic codes has been proposed thus far. In this study, we propose an approach for the efficient and systematic construction of a cyclically permutable code from a cyclic code by utilizing an algebraic property. The proposed coding method improves the robustness of watermarking, particularly for video frames, against a clipping attack.

DOI： 10.1109/TIT.2006.881834

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

Homomorphic property of public-key cryptosystems is applied for several cryptographic protocols, such as electronic cash, voting system, bidding protocols, etc. Several fingerprinting protocols also exploit the property to achieve an asymmetric system. However, their enciphering rate is extremely low and the implementation of watermarking technique is difficult. In this paper, we propose a new fingerprinting protocol applying additive homomorphic property of Okamoto-Uchiyama encryption scheme. Exploiting the property ingenuously, the enciphering rate of our fingerprinting scheme can be close to the corresponding cryptosystem. We study the problem of implementation of watermarking technique and propose a successful method to embed an encrypted information without knowing the plain value. The security can also be protected for both a buyer and a merchant in our scheme.

DOI： 10.1109/TIP.2005.859383

Web of Science

researchmap

掲載種別：研究論文（学術雑誌）   出版者・発行元：MDPI AG  

The main goal of group testing is to identify a small number of specific items among a large population of items. In this paper, we consider specific items as positives and inhibitors and non-specific items as negatives. In particular, we consider a novel model called group testing with blocks of positives and inhibitors. A test on a subset of items is positive if the subset contains at least one positive and does not contain any inhibitors, and it is negative otherwise. In this model, the input items are linearly ordered, and the positives and inhibitors are subsets of small blocks (at unknown locations) of consecutive items over that order. We also consider two specific instantiations of this model. The first instantiation is that model that contains a single block of consecutive items consisting of exactly known numbers of positives and inhibitors. The second instantiation is the model that contains a single block of consecutive items containing known numbers of positives and inhibitors. Our contribution is to propose efficient encoding and decoding schemes such that the numbers of tests used to identify only positives or both positives and inhibitors are less than the ones in the state-of-the-art schemes. Moreover, the decoding times mostly scale to the numbers of tests that are significantly smaller than the state-of-the-art ones, which scale to both the number of tests and the number of items.

DOI： 10.3390/e24111562

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/jimaging8060152

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/info13050211

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.22667/JOWUA.2022.03.31.033

researchmap

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

DOI： 10.1109/LifeTech53646.2022.9754807

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/lifetech/lifetech2022.html#HtetFKZSAK22

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

DOI： 10.1109/LifeTech53646.2022.9754593

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/lifetech/lifetech2022.html#LuCFKU22

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

DOI： 10.1109/LifeTech53646.2022.9754790

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/lifetech/lifetech2022.html#PuspitaningayuF22

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1587/transinf.2021mup0005

researchmap

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1007/978-3-031-14463-9_16

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/cdmake/cdmake2022.html#KuribayashiKF22

掲載種別：研究論文（学術雑誌）  

DOI： 10.12720/jcm.17.8.592-599

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.4018/ijmcmc.301275

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.48550/arXiv.2208.07070

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3390/app112210928

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NEWSWOOD LTD  

Currently, Android smartphones have dominated the distribution of mobile devices around the world. Then, with high demands for Android programming jobs, large numbers of schools, universities, and professional training institutions offer related courses. The Android Programming Learning Assistance System (APLAS) has been developed to accommodate independent and automatic assisting learning for students to learn Android programming by adopting test-driven development (TDD) method. APLAS offers learning materials to systematically study Android programming through solving topics with four stages and provides features for automatic validation of the student's answers by running given test codes. However, a platform to support various activities of teachers for handling a lot of students in the courses is not implemented yet, and it made their load become very high. This paper presents the proposal of online platform in APLAS for distributing the learning materials, collecting the student's answers, and validating them, based on a web application system. By using Gradle, a validator program was developed for running the test codes automatically in the server when a new answer is submitted. A comprehensive evaluation has been applied by asking 60 undergraduate students in an Indonesian university to use the online platform, solve three APLAS learning topics, and submit the answers. The results showed that the three functions worked properly, and the validation process of 183 submissions from all students delivered correct results on the server. The stability, robustness, effectiveness, performance, and security of the online platform were confirmed by analyzing the data of users' activities and validation results. The significant reduction in processing time on all three functions also confirmed its effectiveness and improvement. Finally, the students' feedback proved its usability.

Web of Science

researchmap

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ACM  

DOI： 10.1145/3437880.3460402

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/ih/ihmmsec2021.html#KuribayashiTSYF21

掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s42979-021-00580-1

researchmap

掲載種別：研究論文（学術雑誌）  

researchmap

その他リンク： https://dblp.uni-trier.de/db/journals/ijnc/ijnc11.html#BriantoroFRMKK21

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Currently, the IEEE 802.11n wireless local-area network (WLAN) has been extensively deployed world-wide. For the efficient channel assignment to access-points (APs) from the limited number of partially overlapping channels (POCs) at 2.4GHz band, we have studied the throughput drop estimation model for concurrently communicating links using the channel bonding (CB). However, non-CB links should be used in dense WLANs, since the CB links often reduce the transmission capacity due to high interferences from other links. In this paper, we examine the throughput drop estimation model for concurrently communicating links without using the CB in 802.11n WLAN, and its application to the POC assignment to the APs. First, we verify the model accuracy through experiments in two network fields. The results show that the average error is 9.946% and 6.285% for the high and low interference case respectively. Then, we verify the effectiveness of the POC assignment to the APs using the model through simulations and experiments. The results show that the model improves the smallest throughput of a host by 22.195% and the total throughput of all the hosts by 22.196% on average in simulations for three large topologies, and the total throughput by 12.89% on average in experiments for two small topologies.

DOI： 10.1587/transinf.2020NTP0008

Web of Science

Scopus

researchmap

その他リンク： https://dblp.uni-trier.de/db/journals/ieicetd/ieicetd104.html#MuneneFBRAKK21

掲載種別：研究論文（学術雑誌）  

researchmap

その他リンク： https://dblp.uni-trier.de/db/journals/corr/corr2107.html#abs-2107-02961

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

Currently, we are studying the Programming Learning Assistant System (PLAS) to assist self-studies of C/C++/Java/JavaScript/Python programming. Previously, we implemented the offline answering function on a Web browser for the element fill-in-blank problem (EFP) in PLAS. EFP requests filling in the blank elements in a given source code, where the correctness of any answer element is validated through string matching using the JavaScript program. The code completion problem (CCP) is the generalization of EFP for coding and debugging study. CCP requests completing the code that has missing elements, where the correctness of any statement is validated. In this paper, we implement the offline answering function for CCP by modifying the one for EFP. The two-level marking function is newly adopted to encourage students to be aware of the correct usage of tabs and spaces in the source code for readable code. We verify the correctness of the implementation through solving various CCP instances.

DOI： 10.1109/LifeTech52111.2021.9391894

Web of Science

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/lifetech/lifetech2021.html#KyawFK21

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jisa.2021.102875

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ACM  

DOI： 10.1145/3465481.3470088

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/IEEEares/ares2021.html#MegiasKRM21

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER INTERNATIONAL PUBLISHING AG  

Currently, the IEEE 802.11n wireless local-area network (WLAN) has been broadly deployed world-wide for flexible and high-speed Internet access communications. Since it uses the limited number of partially overlapping channels (POCs) at 2.4 GHz band, the throughput performance is often degraded by interferences from signals of other WLANs. Thus, we have studied throughput drop estimation models for concurrently communicating multiple links under interferences, where the 40 MHz channel bonding (CB) and 20 MHz non-CB are considered separately. We have observed that the simultaneous use of CB and non-CB can improve the performance by enhancing the channel capacity while reducing the interference. In this paper, we study the throughput drop estimation model for concurrently communicating links under coexistence of CB and non-CB in IEEE 802.11n WLAN. The model accuracy is verified by comparing the estimated throughput with the measured one under various network topologies.

DOI： 10.1007/978-3-030-79725-6_71

Web of Science

Scopus

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/cisis/cisis2021.html#MuneneFBRRK21

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ACM  

DOI： 10.1145/3479162.3479176

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/icccm/icccm2021.html#HtetFKZK21

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

DOI： 10.1109/ICCE-TW52618.2021.9603037

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/icce-tw/icce-tw2021.html#PuspitaningayuF21

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

C programming has been the fundamental subject to a lot of university students for studying programming languages, algorithms, and computer architecture. Currently, we are developing C programming learning assistant system (CPLAS) for its self-study by extending our works of JPLAS for Java programming. JPLAS provides the code completion problem (CCP) to offer practical programming exercises. A CCP instance asks the completion of the given source code by filling in the missing elements. The correctness of the answer is marked through string matching by comparing each answer statement with the correct one. In this paper, we present the CCP by extending our works of the element fill-in-blank problem (EFP) in CPLAS. For evaluations, we generated 10 CCP instances and assigned them to 54 undergraduate students in Myanmar and Japan. Their solution results show that the CCP instances are generally suitable for C programming study by novice students, but those on pointer need improvements for better solutions.

DOI： 10.1109/ICIET51873.2021.9419621

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

researchmap

その他リンク： https://dblp.uni-trier.de/rec/conf/apsipa/2021

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

DOI： 10.1109/CANDARW53999.2021.00051

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/ic-nc/candar2021w.html#KamoyedjiFHK21

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

researchmap

その他リンク： https://dblp.uni-trier.de/rec/conf/apsipa/2021

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

その他リンク： https://dblp.uni-trier.de/rec/conf/apsipa/2021

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

その他リンク： https://dblp.uni-trier.de/rec/conf/apsipa/2021

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：EMERALD GROUP PUBLISHING LTD  

PurposeWith rapid increase of Android devices and application systems, there is a strong demand for Android application programmers. A lot of schools are offering Android programming courses to meet this demand. However, Android programming can be different from the conventional one because it needs interactive functions through interfaces with users, which makes the study more difficult. This paper aims to propose an Android Programming Learning Assistance System, namely, APLAS, to assist the Java-based Android programming study and education.Design/methodology/approachBy adopting the test-driven development method, APLAS is designed to achieve independent learning without the presence of teachers. Using JUnit and Robolectric, the answers from the students are automatically marked in APLAS. To cover extensive materials in Android programming, APLAS offers four stages where each stage involves several topics.FindingsTo evaluate the effectiveness of APLAS, we implemented the Unit Converter assignment that covers the first two topics, namely, Basic user interface in the first stage and basic activity in the second stage. Through solving the assignment, it is expected to learn basic application development. Forty novice students of an IT department in Indonesia were asked to solve both topics separately.Originality/valueThe results show that APLAS is useful and helpful for the self-study of Android programming, as they could complete codes with good execution performances.

DOI： 10.1108/IJWIS-08-2019-0038

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IGI GLOBAL  

The IEEE802.11n wireless local-area network (WLAN) has been widely adopted due to the flexible coverage and lower installation cost. However, the TCP throughput unfairness was detected when multiple hosts concurrently communicate with a single access-point (AP). Previously, the authors proposed the TCP fairness control method for only two hosts in the elastic WLAN system using Raspberry Pi AP, which dynamically adapts the topology according to the traffic demand. The delay is introduced in the packet transmission to the faster host from the AP, which is optimized by the PI feedback control such that the measured throughput becomes equal between the hosts. In this paper, the authors proposed a generalization of this method for any number of hosts by newly introducing the target throughput as the equal goal among the hosts. It is dynamically updated using the measured throughputs. The effectiveness of the proposal is verified through experiments using the elastic WLAN system testbed with one AP and up to four hosts.

DOI： 10.4018/IJMCMC.2020040102

Web of Science

Scopus

researchmap

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)  

DOI： 10.1007/978-3-030-43575-2_14

Scopus

researchmap

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Lecture Notes in Networks and Systems  

DOI： 10.1007/978-3-030-61108-8_15

Scopus

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/bwcca/bwcca2020.html#HudaFKSIK20

掲載種別：研究論文（学術雑誌）   出版者・発行元：Advances in Intelligent Systems and Computing  

DOI： 10.1007/978-3-030-29029-0_23

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MDPI  

Copyright protection is one of the most relevant challenges in the network society. This paper focuses on digital fingerprinting, a technology that facilitates the tracing of the source of an illegal redistribution, making it possible for the copyright holder to take legal action in case of copyright violation. The paper reviews recent digital fingerprinting solutions that are available for two particularly relevant scenarios: peer-to-peer distribution networks and broadcasting. After analyzing those solutions, a discussion is carried out to highlight the properties and the limitations of those techniques. Finally, some directions for further research on this topic are suggested.

DOI： 10.3390/computers9020026

Web of Science

Scopus

researchmap

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

DOI： 10.1109/ICCE46568.2020.9043042

Scopus

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/iccel/icce2020.html#HudaFKK20

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

DOI： 10.1109/CANDARW51189.2020.00015

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/ic-nc/candar2020w.html#BriantoroFMRAKK20

掲載種別：研究論文（学術雑誌）  

DOI： 10.1108/IJWIS-07-2019-0032

Scopus

researchmap

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

researchmap

その他リンク： https://dblp.uni-trier.de/conf/apsipa/2020

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

researchmap

その他リンク： https://dblp.uni-trier.de/conf/apsipa/2020

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

researchmap

その他リンク： https://dblp.uni-trier.de/conf/apsipa/2020

掲載種別：研究論文（学術雑誌）  

DOI： 10.4018/IJMCMC.2020100101

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ASSOC COMPUTING MACHINERY  

With the growing popularity of smartphone devices, the demand for mobile application programmers has been increasing, particularly for the most popular mobile platform Android. Then, Android application programming has become one of the most important subjects that students should learn in professional schools and universities in IT departments. To assist self-studies of students, we have developed Android Programming Learning Assistance System (APLAS). To guide students to reach correct answers for given assignments, APLAS adopts the Test-Driven Development (TDD) method to validate student answers automatically using JUnit and Robolectric. The learning model for APLAS consists of four stages where each stage has several topics. In this paper, we implement Advanced Widgets as the second topic in the Interactive Application stage and evaluate it through applications to students in an IT department in Indonesia.

DOI： 10.1145/3395245.3396198

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

researchmap

掲載種別：研究論文（学術雑誌）  

researchmap

掲載種別：研究論文（学術雑誌）  

researchmap

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

DOI： 10.1109/APSIPAASC47483.2019.9023302

Scopus

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/apsipa/apsipa2019.html#KuribayashiF19

掲載種別：研究論文（学術雑誌）  

DOI： 10.25046/aj040411

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

The IEEE802.11 wireless local-area network (WLAN) has been extensively deployed as inexpensive and flexible Internet access services. We have studied the elastic WLAN system that dynamically optimizes the network configuration depending on traffic demands. Our testbed experiments using Raspberry Pi revealed that concurrent TCP communications of multiple hosts with a single AP cause the unfairness in throughput performances. In this paper, we propose the TCP fairness control method for two-host concurrent communications. The delay is introduced in the AP at the packet transmissions to the faster host, to increase transmission opportunities with the slower host. The delay is initially estimated by the received signal strength (RSS) from each host, and then, is dynamically optimized using the PI controller. For evaluations, we implement the proposal in the elastic WLAN system testbed, and conduct extensive experiments, where the TCP throughput fairness is achieved.

DOI： 10.25046/aj040602

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

In the contemporary world of information technology, PDF (Portable Document Format) has become the de facto document standard which allows users to exchange and view electronic documents across various platforms. PDF is the most widely exchanged document format since Internet gained popularity. Although PDF has a good authenticity system by making use of digital signatures, the file format is still susceptible to copyright infringement as there are many libraries available on the Internet to bypass the digital signature of a PDF. Therefore, claiming ownership for PDF has become a paramount issue that needs to be addressed. This paper proposes the idea of hiding data in the glyph positioning coordinate value. To suppress bit stream size increment, the reverse zero-run length coding technique is adopted. Experiments are conducted to verify the basic performance of the proposed data hiding method. In the best case scenario, 0.62 bits of data can be embedded into each Byte of the PDF file. The injected leading zeros can be removed to restore the original PDF file.

DOI： 10.1109/APSIPAASC47483.2019.9023310

Web of Science

researchmap

その他リンク： https://dblp.uni-trier.de/db/conf/apsipa/apsipa2019.html#NursiahWK19

掲載種別：研究論文（学術雑誌）  

DOI： 10.12720/jcm.14.11.1009-1016

Scopus

researchmap

掲載種別：研究論文（学術雑誌）   出版者・発行元：Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)  

DOI： 10.1007/978-3-030-17982-3_19

Scopus

researchmap

掲載種別：研究論文（学術雑誌）  

researchmap

その他リンク： https://dblp.uni-trier.de/db/journals/ijnc/ijnc9.html#KoderaKKN19

掲載種別：研究論文（学術雑誌）  

DOI： 10.1587/transinf.2018MUP0003

Scopus

researchmap

その他リンク： https://dblp.uni-trier.de/db/journals/ieicet/ieicet102d.html#KuribayashiFF19

掲載種別：研究論文（学術雑誌）  

DOI： 10.2197/ipsjjip.27.245

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：INDERSCIENCE ENTERPRISES LTD  

As a flexible and cost-efficient internet access network, the IEEE 802.11 wireless local-area network (WLAN) has been broadly deployed around the world. Previously, to improve the IEEE 802.11n WLAN performance, we proposed the four-step minimax access-point (AP) setup optimisation approach: 1) link throughputs between the AP and hosts in the network field are measured manually; 2) the throughput estimation model is tuned using the measurement results; 3) the bottleneck host suffering the least throughput is estimated using this model; 4) the AP setup is optimised to maximise the throughput of the bottleneck host. Unfortunately, this approach has drawbacks: 1) a lot of manual throughput measurements are necessary to tune the model; 2) the shift of the AP location is not considered; 3) IEEE 802.11ac devices at 5 GHz are not evaluated, although they can offer faster transmissions. In this paper, we present the three enhancements: 1) the number of measurement points is reduced while keeping the model accuracy; 2) the coordinate of the AP setup is newly adopted as the optimisation parameter; 3) the AP device with IEEE 802.11ac at 5 GHz is considered with slight modifications. The effectiveness is confirmed by extensive experiments in three network fields.

DOI： 10.1504/IJSSC.2019.100017

Web of Science

researchmap

掲載種別：研究論文（学術雑誌）   出版者・発行元：Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)  

DOI： 10.1007/978-3-030-14812-6_7

Scopus

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.17706/jsw.14.5.200-208

researchmap

掲載種別：研究論文（学術雑誌）  

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

To advance Java programming educations, Java Programming Learning Assistant System (JPLAS) has been developed and used in universities in Japan and Myanmar. JPLAS offers several types of programming exercises to cover different learning levels, including the element fill-in-blank problem (EFP) and the code completion problem (CCP). In CCP, an incomplete source code made by removing some elements is given to a student, and its completion is requested by filling in the missing elements properly. The answer is marked by comparing each statement with the corresponding one in the original code. In contrast to EFP, CCP does not show the locations of missing elements. In the trial, CCP has been implemented on offline JPLAS. Data exchange between a teacher and students in a Java programming course is made using USB memories, which takes large loads. In this paper, we implement CCP on the Web server for online JPLAS by extending the implementation of EFP. As well, the evaluations have confirmed the effectiveness of this implementation.

Web of Science

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.1587/transfun.E101.A.119

Web of Science

Scopus

researchmap

出版者・発行元：IEEE  

DOI： 10.1109/ITW.2018.8613319

researchmap

掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE Computer Society  

DOI： 10.1109/CANDARW.2018.00061

researchmap

出版者・発行元：IEEE  

DOI： 10.1109/ISIT.2018.8437847

Web of Science

researchmap

researchmap

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s11042-017-5230-8

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

DOI： 10.23919/APSIPA.2018.8659681

Web of Science

researchmap

researchmap

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.1504/IJSSC.2018.097286

researchmap

掲載種別：研究論文（学術雑誌）   出版者・発行元：Smart Innovation, Systems and Technologies  

DOI： 10.1007/978-3-319-63856-0_47

Web of Science

Scopus

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.jisa.2018.06.002

Web of Science

Scopus

researchmap

掲載種別：研究論文（学術雑誌）  

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

In conventional spread spectrum (SS) watermarking schemes, random sequences are used for the modulation of watermark information. However, because of the mutual interference among those sequences, it requires complicated removal operation to improve the performance. In this paper, we propose an efficient spread spectrum watermarking scheme by introducing the orthogonal frequency divisiion multiplexing (OFDM) technique at the modulation of watermark information. The SS sequences in the proposed method are the DCT basic vectors modulated by a pseudo-random number (PN) sequence. We investigate the SS-based method considering the host interference at the blind detection scenario and analyze the noise caused by attacks. Because every operation is invertible, the quantization index modulation (QIM)-based method is applicable for the OFDM modulated signals. We also consider the property of watermark extracting operation in SS-based and QIM-based method and formalize their models of noisy channel in order to employ an error correcting code. The performance of their methods with error correcting code is numerically evaluated under the constraints of same distortion level in watermarked content. The experimental results indicated a criteria for the selection of SS-based and QIM-based methods for given content, which is determined by the amount of host interference. In case that the host interference is 0.8 times smaller than a watermark signal, the SS-based method is suitable. When it is 1.0 times larger, the QIM-based method should be selected.

DOI： 10.1587/transfun.E100.A.944

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Within information hiding technology, digital watermarking is one of the most important technologies for copyright protection of digital content. Many digital watermarking schemes have been proposed in academia. However, these schemes are not used, because they are not practical; one reason for this is that the evaluation criteria are loosely defined. To make the evaluation more concrete and improve the practicality of digital watermarking, watermarking schemes must use common evaluation criteria. To realize such criteria, we organized the Information Hiding and its Criteria for Evaluation (IHC) Committee to create useful, globally accepted evaluation criteria for information hiding technology. The IHC Committee improves their evaluation criteria every year, and holds a competition for digital watermarking based on state-of-the-art evaluation criteria. In this paper, we describe the activities of the IHC Committee and its evaluation criteria for digital watermarking of still images, videos, and audio.

DOI： 10.1587/transinf.2016MUI0001

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Quick Response (QR) code is a two dimensional barcode widely used in many applications. A standard QR code consists of black and white square modules, and it appears randomized patterns. By modifying the modules using certain rule, it is possible to display a logo image on the QR code. Such a QR code is called an aesthetic QR code. In this paper, we change the encoding method of the Reed-Solomon (RS) code to produce an aesthetic QR code without sacrificing its error correcting capability. The proposed method randomly produces candidates of RS blocks and finds the best one during encoding. Considering an image to be displayed, we also introduce a weighting function during random selection that classifies the visually important regions in the image. We further investigate the shape of modules which represents the image and consider the trade-off between the visual quality and its readability. As a result, we can produce a beautiful aesthetic QR code, which still can be decoded by standard QR code reader.

DOI： 10.1587/transinf.2016MUP0002

Web of Science

Scopus

researchmap

出版者・発行元：IEEE  

DOI： 10.1109/APSIPA.2017.8282268

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

To improve Java programming educations, we have developed a Web-based Java Programming Learning System (JPLAS). To deal with students at different levels, JPLAS provides three levels of problems, namely, element fill-in-blank problems, statement fill-in-blank problems, and code writing problems. Unfortunately, since JPLAS has been implemented by various students who studied in our group at different years, the code has become complex and redundant, which makes further extensions of JPLAS extremely hard. In this paper, we propose the software architecture for JPLAS to avoid redundancy to the utmost at implementations of new functions that will be continued with this JPLAS project. Following the MVC model, our proposal basically uses Java for the model (M), JavaScript/CSS for the view (V), and JSP for the controller (C). For the evaluation, we implement JPLAS by this architecture and compare the number of code files with the previous implementation.

DOI： 10.1109/AINA.2017.56

Web of Science

researchmap

researchmap

出版者・発行元：IEEE Computer Society  

DOI： 10.1109/CANDAR.2017.20

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER INTERNATIONAL PUBLISHING AG  

An aesthetic 2D-barcode, e.g. QR code, carries a given message in the payload and yet its visual appearance resembles another given logo image. The requirement of embedding a message in a "cover" image is similar to digital watermarking but with a crucial difference that, for the aesthetic 2D-barcode, the decoder is predetermined and fixed. Hence the designs and performances of the aesthetic 2D-barcode heavily rely on the predetermined decoder. In this paper, we focus on the underlying systematic encoding function in QR code. We first formulate a framework that optimizes the visual appearance of the codeword and yet meets the coding requirement. Since finding such an optimal codeword is computationally expensive, we next propose a heuristic to search for a feasible solution, and incorporate image processing operations to enhance the visual appearance. Although our method is designed for QR code, our approach can be applied to other 2D-barcodes that employ similar coding mechanisms of error correction code.

DOI： 10.1007/978-3-319-53465-7_28

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER INTERNATIONAL PUBLISHING AG  

An aesthetic 2D-barcode, e.g. QR code, carries a given message in the payload and yet its visual appearance resembles another given logo image. The requirement of embedding a message in a "cover" image is similar to digital watermarking but with a crucial difference that, for the aesthetic 2D-barcode, the decoder is predetermined and fixed. Hence the designs and performances of the aesthetic 2D-barcode heavily rely on the predetermined decoder. In this paper, we focus on the underlying systematic encoding function in QR code. We first formulate a framework that optimizes the visual appearance of the codeword and yet meets the coding requirement. Since finding such an optimal codeword is computationally expensive, we next propose a heuristic to search for a feasible solution, and incorporate image processing operations to enhance the visual appearance. Although our method is designed for QR code, our approach can be applied to other 2D-barcodes that employ similar coding mechanisms of error correction code.

DOI： 10.1007/978-3-319-53465-7_28

Web of Science

researchmap

記述言語：英語   出版者・発行元：IJNC編集委員会  

Recently, an IEEE 802.11n access point (AP) prevailed over the wireless local area network (WLAN) due to the high-speed data transmission using the multiple input multiple output (MIMO) technology. Unfortunately, the signal propagation from the 802.11n AP is not uniform in the circumferential and height directions because of the multiple antennas for MIMO. As a result, the data transmission speed between the AP and a host could be significantly affected by their relative setup conditions. In this paper, we propose a minimax approach for optimizing the 802.11n AP setup condition in terms of the angles and the height in an indoor environment using throughput measurements. First, we detect a bottleneck host that receives the weakest signal from the AP in the field using the throughput estimation model. To explore optimal values of parameters for this model, we adopt the versatile parameter optimization tool. Then, we optimize the AP setup by changing the angles and the height while measuring throughput. For evaluations, we verify the accuracy of the model using measurement results and confirm the throughput improvements for hosts in the field by our approach.

DOI： 10.15803/ijnc.7.2_187

CiNii Article

researchmap

その他リンク： http://dblp.uni-trier.de/db/journals/ijnc/ijnc7.html#journals/ijnc/LwinFTZMKK17

DOI： 10.1504/IJICOT.2017.10004711

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

In this paper, we focus on auditing for users' operation behaviors, which is significant for the avoidance of potential crimes in the cloud and equitable accountability determination in the forensic. We first present a public model for operation behaviors in cloud storage, in which a trusted third party is introduced to verify the integrity of operation behavior logs to enhance the credibility of forensic results as well as alleviate the burden of the forensic investigator. Further, we design a block-based logging approach to support selective verification and a hash-chain-based structure for each log block to ensure the forward security and append-only properties for log entries. Moreover, to achieve the tamper resistance of log blocks and non-repudiation of auditing proofs, we employ Merkle hash tree (MHT) to record the hash values of the aggregation authentication block tags sequentially and publish the root of MHT to the public once a block has been appended. Meanwhile, using the authentication property of MHT, our scheme can provide log-less verification with privacy preservation. We formally prove the security of the proposed scheme and evaluate its performance on entry appending and verification by concrete experiments and comparisons with the state-of-the-art schemes. The results demonstrate that the proposed scheme can effectively achieve secure auditing for log files of operation behaviors in cloud storage and outperforms the previous ones in computation complexity and communication overhead.

DOI： 10.1007/s00500-016-2311-y

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Based upon the Kerckhoffs' principle, illegal users can get to know the embedding and detection algorithms except for a secret key. Then, it is possible to access to a host signal which may be selected from frequency components of a digital content for embedding watermark signal. Especially for a fingerprinting scheme which embeds user's information as a watermark, the selected components can be easily found by the observation of differently watermarked copies of a same content. In this scenario, it is reported that some non-linear collusion attacks will be able to remove/modify the embedded signal. In this paper, we study the security analysis of our previously proposed spread-spectrum (SS) fingerprinting scheme [1], [2] under the Kerckhoffs' principle, and reveal its drawback when an SS sequence is embedded in a color image. If non-linear collusion attacks are performed only to the components selected for embedding, the traceability is greatly degraded while the pirated copy keeps high quality after the attacks. We also propose a simple countermeasure to enhance the robustness against non-linear collusion attacks as well as possible signal processing attacks for the underlying watermarking method.

DOI： 10.1587/transinf.2015MUP0005

Web of Science

researchmap

researchmap

その他リンク： http://dblp.uni-trier.de/db/journals/ijnc/ijnc6.html#journals/ijnc/MamunIFKL16

掲載種別：研究論文（学術雑誌）   出版者・発行元：Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)  

DOI： 10.1007/978-3-319-31960-5_14

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Verlag  

The digital watermark is used for copyright protection, and the methods should have the robustness against various attacks such as JPEG compression, clipping, rotation, and scaling attacks. Based on the DCT-OFDM based watermarking method presented at IWIHC2014, we propose a method enhancing the performance in this paper. There are two ideas in the proposed method. One idea is to reduce the computational costs required for the synchronization recovery. The other idea is to encode watermark information by error correcting code and to decode it by maximum likelihood algorithm. As the result, our method has high robustness against the IHC evaluation criteria with less degradation of quality and less computational costs.

DOI： 10.1007/978-3-319-31960-5_23

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Springer Verlag  

Quick Response (QR) code is a two dimensional barcode widely used in many applications. Similar to a visible watermarking technique, the visual appearance can be modified to display an image while a standard QR code reader can decode the data contained in such a QR code. In this paper, we consider the characteristic of images to be displayed on a QR code, and propose an effective method to produce a visually better aesthetic QR code without sacrificing its error correcting capability. We also investigate the shape of modules to represent the image to be displayed and consider the trade-off between the visual quality and its readability.

DOI： 10.1007/978-3-319-31960-5_18

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

Currently, high-speed IEEE802.11n interfaces using MIMO have become common in access points (APs) and personal computers (PCs) for wireless local-area networks (WLANs). This trend leads to further expand the application areas for WLANs. In this paper, we present throughput measurement results of IEEE802.11n devices with various placement orientations in indoor environments. They show that measured throughputs are strongly affected by the roll and yaw angles at the installation of AP due to the multiple antennas in MIMO, which should be considered in optimizing the installation of APs in indoor fields.

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

The User-PC computing system (UPC) has been studied to provide a parallel computing platform for members in a group using idling computing resources in personal computers (PCs) of them. UPC adopts the master-worker model where we have implemented the programs for the master on Linux and for the worker on Linux and Windows. However, the current job scheduling method does not consider the real performance of a worker PC. In this paper, we implement a function to measure the performance of a worker PC using two benchmark programs. The experiment results for six PCs in our group show that there are three times difference in the CPU performance and eight times difference in the disk performance.

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

To assist Java programming educations, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). JPLAS provides fill-in-blank problems to let students study Java grammar and basic programming skills by filling the blanked elements in a given Java code. To generate the feasible problems, we have proposed a blank element selection algorithm using the constraint graph to select as many blanks as possible such that they have grammatically correct and unique answers. In this paper, to further increase the number of blanks and control the difficulty of the generated problem, we extend this algorithm by 1) adding operators in conditional expressions for blank candidates, 2) improving the edge generation method in the constraint graph to increase the number of blanks, and 3) introducing two parameters to change the frequency of selecting blanks. To verify the effectiveness, we apply the extended algorithm to 55 Java codes for fundamental data structure or algorithms, and confirm that these extensions can increase the number of blanks and change the problem difficulty.

DOI： 10.1109/GCCE.2016.7800312

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

Recently, Java has been educated in many universities and professional schools due to reliability, portability, and scalability. However, because of its limited time in Java programming courses, coding rules arc rarely educated. As a result, codes made by students become far from readable codes. In this paper, we propose a coding rule learning function using static code analyzers in Java Programming Learning Assistant System (JPLAS), targeting students who have accomplished the grammar learning and are going to write practical codes for final projects. Coding rules for this function consist of naming rules, coding styles, and potential problems. We evaluate the improvement of readability in four codes refined by this function and the usability of this function through the questionnaires completed by five students. In future studies, we expect that this function will be employed in Java programming courses.

DOI： 10.1109/CISIS.2016.94

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

The study of universal detector for fingerprinting code is strongly dependent on the design of scoring function. The best detector is known as the MAP detector that calculates an optimal correlation score, but the number of colluders and their collusion strategy are inevitable. Although there are some scoring functions under some collusion strategies and asymptotic analyses, their numerical evaluation has not been done. In this study, their performance is evaluated for some typical collusion strategies using a discretized bias-based binary fingerprinting code. We also propose a simple but efficient scoring function based on a heuristic observation.

DOI： 10.1109/ICASSP.2016.7472035

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

Recently, an IEEE802.11n access point (AP) has become common in the wireless local-area network (WLAN) due to the high-speed data transmission using the multiple input multiple output (MIMO) technology. However, the signal propagation from the 802.11n AP may not be uniform in the circumferential direction because of multiple antennas in MIMO, in addition to the height direction. As a result, the data transmission speed between the AP and a host can be significantly affected by their relative setup conditions. In this paper, we propose a minimax approach for optimizing the 802.11n AP setup condition in terms of the angles and the height in an indoor environment using throughput measurements. First, we detect a bottleneck host that receives the weakest signal from the AP in the field using the throughput estimation model. Then, we optimize the AP setup by changing the orientation and height while measuring throughputs. For evaluations, we confirm the accuracy of the model using measurement results and the throughput improvements at most hosts including the bottleneck one in the field by our approach.

DOI： 10.1109/CANDAR.2016.37

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

According to watermark security based on the Kerckhoffs' principle, we should mind that illegal users will be able to access to the host signal which is targeted for embedding in a fingerprinting system. In our system, each user's ID is encoded by a fingerprinting code, and then it is embedded into the host signal employing the obfuscation technique. Considering the operation in the obfuscation technique, we discover that the operation is equivalent to a simple spread spectrum (SS) watermarking method using longer sequences. Its effects are intensively evaluated by simulation in this paper.

DOI： 10.1109/ICIP.2015.7351175

Web of Science

researchmap

出版者・発行元：ACM  

DOI： 10.1145/2598908

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

In the spread spectrum (SS) fingerprinting technique, the averaging attack has been supposed to be the most damaging attack. It is because a number of nonlinear collusion strategies is supposed to be well approximated by averaging collusion plus additive noise. In this study, we intensively evaluate the conventional assumption, and reveal its drawbacks when a SS sequence is embedded in a digital image. Furthermore, we propose a simple and effective method to improve the drawbacks by introducing a spreading operation at the embedding. Our experimental results reveal that the damages caused by non-linear collusion strategies can be reduced in such a way that the host signal sampled from an image is kept secret.

Web of Science

researchmap

その他リンク： http://dblp.uni-trier.de/db/conf/isita/isita2014.html#conf/isita/Kuribayashi14

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ASSOC COMPUTING MACHINERY  

Robustness against various attacks involving lossy compression like JPEG and clipping is inevitable requirements for digital watermarking schemes. In this paper, we propose a watermarking scheme robust against the JPEG compression and a clipping attack using the DCT-OFDM based watermarking method. Robustness against the JPEG compression can be achieved by embedding watermark information into the low -frequency components. We employ the QIM method to the DCT-OFDM modulated signal. By embedding a synchronization signal, we attempt to recover the synchronization loss from a clipped image. In a preliminary experiment, we can detect the embedded synchronization signal around a correct synchronization point because the synchronization signal is mainly embedded into the low frequency components in a spread form. Then, we determine the center among the detected points as the correct synchronization point. We evaluate the performance of our method by computer simulation. It is revealed that our method satisfies the evaluation criteria determined by IHC Committee, while maintaining high image quality.

DOI： 10.1145/2598908.2598914

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Springer-Verlag  

In conventional spread spectrum watermarking schemes, random sequences are used for the modulation of watermark information. However, because of the mutual interference among those sequences, it requires complicated removal operation to improve the performance. In this paper, we propose an efficient spread spectrum watermarking scheme by introducing the CDMA technique at the modulation of watermark information. In order to control the energy assigned to spread spectrum sequences, we propose a coded method that encodes watermark information into a constant weight codeword. If the weight and its code-length are properly selected, the performance of the method could outperform the conventional methods. © 2013 Springer-Verlag.

DOI： 10.1007/978-3-642-40099-5_15

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Springer-Verlag  

In binary probabilistic fingerprinting codes, the number of symbols "0" and "1" is generally balanced because of the design of the codeword. After a collusion attack, the balance of symbols is not always assured in a pirated codeword. It is reported in [8] that if the number of symbols in a pirated codeword is unbalanced, then a tracing algorithm can be improved by equalizing the unbalanced symbols. In this study, such a bias equalizer is customized for probabilistic fingerprinting codes utilizing the encoding parameters. Although the proposed bias equalizer is highly dependent on collusion strategies, it can improve the performance of traceability for some typical strategies to which the conventional bias equalizer can not be applied. © 2013 Springer-Verlag.

DOI： 10.1007/978-3-642-36373-3_18

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ACM  

When a binary fingerprinting codeword is embedded into digital contents using a spread-spectrum (SS) watermarking scheme, the marking assumption is not valid anymore because it is difficult for colluders to perform the symbol-wise attack for their codewords. As discussed in the SS-type fingerprinting schemes, veraging their copies is the cost-effective attack from the signal processing point of view. In this paper, we propose an optimal detector under the averaging attack and addition of white Gaussian noise. If the detector knows the number of colluders in advance, it first estimates the variance of additive noise, and then calculates the correlation scores using a log-likelihood-based approach. However, the number of colluders is not given in a real situation. We discover in this study that the characteristic of parameters for generating codewords enables us to eliminate the number of colluders as well as the estimation of the variance of noise at the calculation of correlation score, and propose a simplified detector by analyzing the scoring function in the optimal detector. We evaluate the performance of the simplified detector through simulation using not only codewords, but also a digital image. © 2013 ACM.

DOI： 10.1145/2482513.2482521

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

The traceability of the spread spectrum fingerprinting has been improved by an iterative detection method combined with an interference removal operation. However, the false-positive probability is slightly increased when the length of fingerprint sequence is rather small. In this study, the iterative detection procedure is adaptively calibrated to maximize the effect of the interference removal operation.

DOI： 10.1109/ICASSP.2012.6288244

Web of Science

researchmap

出版者・発行元：Springer  

DOI： 10.1007/978-3-642-40099-5_15

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

There are many studies on the performance of binary fingerprinting codes under a well-known marking assumption. Among many fingerprinting codes, we focus on Tardos codes and Nuida's variants. From the signal processing point of view, the relaxation of the assumption is required for the analysis. In this paper, we consider the averaging attack which has been studied in the spread-spectrum-based fingerprinting schemes, and propose an optimal detector based on a maximum likelihood decoding. From our theoretical analysis about the effect on a pirated codeword caused by the averaging attack, it is revealed that the false-positive probability is strongly dependent on the number of colluders.

Web of Science

researchmap

その他リンク： http://dblp.uni-trier.de/db/conf/isita/isita2012.html#conf/isita/Kuribayashi12

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER-VERLAG BERLIN  

The performance of fingerprinting codes has been studied under the well-known marking assumption. In a realistic environment, however, a pirated copy will be distorted by an additional attack. Under the assumption that the distortion is modeled as AWGN, a soft decision method for a tracing algorithm has been proposed and the traceability has been experimentally evaluated. However, the previous soft decision method works directly with a received signal without considering the communication theory. In this study, we calculate the likelihood of received signal considering a posterior probability, and propose a soft decision tracing algorithm considering the characteristic of Gaussian channel. For the estimation of channel, we employ the expectation-maximization algorithm by giving constraints under the possible collusion strategies. We also propose an equalizer to give a proper weighting parameter for calculating a correlation score.

DOI： 10.1007/978-3-642-25141-2_1

Web of Science

researchmap

記述言語：英語   出版者・発行元：Hindawi Publishing Corporation  

DOI： 10.1155/2011/502782

CiNii Article

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.1155/2011/502782

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

The iterative detection method was proposed in IH2008 specified for the CDMA-based fingerprinting scheme which embedding procedure was additive watermarking method. Such a detection method is applicable for the multiplicative watermarking method that modulates a fingerprint using the characteristic of a content. In this study, we study the interference among fingerprints embedded in a content in the hierarchical version of Cox's scheme, and propose the effective detection method that iteratively detects colluders combined with a removal operation. By introducing two kinds of thresholds, the removal operation is adaptively performed to reduce the interference without causing serious false detection.

Web of Science

researchmap

掲載種別：研究論文（学術雑誌）  

DOI： 10.1109/IIHMSP.2010.126

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Digital fingerprinting is used to trace back illegal users. where unique ID known as digital fingerprints is embedded into a content before distribution. On the generation of such fingerprints, one of the important properties is collusion-resistance. Binary codes for fingerprinting with a code length of theoretically minimum order were proposed by Tardos, and the related works mainly focused on the reduction of the code length were presented. In this paper, we present a concrete and systematic construction of the Tardos's fingerprinting code using a chaotic map. Using a statistical model for correlation scores, the actual number of true-positive and false-positive detection is measured. The collusion-resistance of the generated fingerprinting codes is evaluated by a computer simulation.

DOI： 10.1587/transfun.E93.A.508

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER-VERLAG BERLIN  

The estimation of the false-positive probability has been an important concern for fingerprinting codes, and the formula of the probability has been derived under a restricted assumption and statistic model. In this paper, we first analyze the statistic behavior of the value of score derived from the correlation between a pirated codeword and codewords of all users when some bits are flipped. Then, the derivation of the score is adaptively designed to consider the attack model such that a pirated codeword is distorted by additive white Gaussian noise. The traceability and probability of false-positive are estimated by Monte-Carlo simulation, and the validity of the Gaussian approximation for the distribution of score is evaluated for probabilistic fingerprinting codes.

DOI： 10.1007/978-3-642-16825-3_9

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE Computer Society  

In the CDMA-based fingerprinting scheme, a fingerprint sequence is composed of two kinds of spread spectrum sequences generated from DCT basic vectors and PN sequences. In this study, the DCT basic vectors are randomly permuted in order to reduce the interference among colluders' fingerprint sequences, which effect is similar to the interleaver used in Turbo codes. Our experimental results reveal that the false-positive probability is reduced without degrading the traceability. © 2010 IEEE.

DOI： 10.1109/IIHMSP.2010.126

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Hindawi Publishing Corporation  

Digital fingerprinting of multimedia contents involves the generation of a fingerprint, the embedding operation, and the realization of traceability from redistributed contents. Considering a buyer's right, the asymmetric property in the transaction between a buyer and a seller must be achieved using a cryptographic protocol. In the conventional schemes, the implementation of a watermarking algorithm into the cryptographic protocol is not deeply discussed. In this paper, we propose the method for implementing the spread spectrum watermarking technique in the fingerprinting protocol based on the homomorphic encryption scheme. We first develop a rounding operation which converts real values into integer and its compensation, and then explore the tradeoff between the robustness and communication overhead. Experimental results show that our system can simulate Cox's spread spectrum watermarking method into asymmetric fingerprinting protocol. Copyright © 2010 Minoru Kuribayashi.

DOI： 10.1155/2010/694797

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER-VERLAG BERLIN  

Binary fingerprinting codes with a length of theoretically minimum order were proposed by Tardos, and the traceability has been estimated under the well-known marking assumption. In this paper, we estimate the traceability and the false-positive probability of the fingerprinting code over AWGN channel, and propose a new accusation algorithm to catch more colluders with less innocent users. The design of our algorithm is based on the symmetric accusation algorithm proposed by Skorie et al. that focuses on the characteristic of the p.d.f. of the correlation scores. The proposed algorithm first estimates the strength of noise added to the code, and then calculates the specific correlation scores among candidate codewords using the characteristic of the noisy channel. The scores are finally classified into guilty and innocent by the threshold obtained from the p.d.f. The performance of the proposed tracing algorithm is evaluated by Monte Carlo simulation.

DOI： 10.1007/978-3-642-16435-4_9

Web of Science

researchmap

DOI： 10.1155/2010/694797

researchmap

掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1145/1655925.1656089

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

On the spread spectrum fingerprinting, it has been considered that the energy of embedded signal is dropped to 1/c of its original value when c copies are averaged. In this study, we analyze the effects of rounding error occurred at the embedding and averaging. The truncation of the number of decimals causes non-linear changes on the frequency components of fingerprint sequence. We estimate the actual attenuation factor through our simulation, and provide the best and worst case. In order to avoid the worst case, the countermeasure is proposed in this paper. © 2009 IEEE.

DOI： 10.1109/IIH-MSP.2009.47

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：ACM  

We have proposed the CDMA-based fingerprinting scheme in IWSEC2007, and the detector is improved by reducing the interference among colluders' fingerprint signals in IH2008. In this study, we evaluate the false-positive detection when the number of colluders is more than 100, and show the bugs in the design of threshold for the determination of guilty. We fix the bugs and further improve the performance by adaptively calculating proper thresholds. Copyright © 2009 ACM.

DOI： 10.1145/1655925.1656089

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE Computer Society  

On the spread spectrum fingerprinting, it has been considered that the energy of embedded signal is dropped to 1/c of its original value when c copies are averaged. In this study, we analyze the effects of rounding error occurred at the embedding and averaging. The truncation of the number of decimals causes non-linear changes on the frequency components of fingerprint sequence. We estimate the actual attenuation factor through our simulation, and provide the best and worst case. In order to avoid the worst case, the countermeasure is proposed in this paper. © 2009 IEEE.

DOI： 10.1109/IIH-MSP.2009.47

Scopus

researchmap

掲載種別：研究論文（国際会議プロシーディングス）  

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

A reversible watermark algorithm with large capacity has been developed by applying the difference expansion of a generalized integer transform. In this algorithm, a watermark signal is inserted in the LSB of the difference values among pixels. In this paper, we apply the prediction errors calculated by a predictor in JPEG-LS for embedding watermark, which contributes to increase the amount of embedded information with less degradation. As one of the drawbacks. discovered in the above conventional method is the large size of the embedded location map introduced to make it reversible, we decrease the large size of the location map by vectorization, and then modify the composition of the map using the local characteristics. We also exclude the positions such that the modification in the embedding operation cannot increase the capacity but merely degrade the image quality, which can be applicable to the conventional methods.

DOI： 10.1093/ietfec/e91-a.7.1780

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER-VERLAG BERLIN  

Digital fingerprinting of multimedia data involves embedding information in the content signal and offers the traceability of illegal users who distribute unauthorized copies. One potential threat to fingerprinting system is collusion, whereby a group of users combines their individual copies in an attempt to remove the underlying fingerprints. Hayashi et. al have proposed hierarchical fingerprinting scheme using the CDMA technique which designed a fingerprint signal by a combination of quasi-orthogonal sequences to increase the allowable number of users. In this paper, we formalize the model of collusion from the viewpoint of a communication channel, and propose a removal operation considering the interference among fingerprints. We also explore the characteristic of the proposed detector and the effects of the removal operation on a detection sequence. By introducing two kinds of thresholds for the determination of the presence of fingerprints, the performance of the proposed detector is enhanced effectively.

DOI： 10.1007/978-3-540-88961-8-25

DOI： 10.1007/978-3-540-88961-8_25

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

This paper presents an improved method of the reversible data hiding for JPEG images proposed by Xuan, et al. The conventional method embeds data into the JPEG quantized 8 x 8 block DCT coefficients. In this method, we found that the blocks, located in the noisy part of the image, are not suitable for embedding data. The proposed method can judge whether a block consisted of 8 x 8 DCT coefficients is located in smooth part of image by using the DC coefficient of neighboring blocks. Our method can avoid the noisy part for embedding. It results in a better performance in terms of capacity-distortion behavior.

DOI： 10.1109/ISITA.2008.4895529

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

Tardos proposed binary codes for fingerprinting with a code length of theoretically minimum order, and the related works mainly focused on the reductio of the code length were presented. We presented a. concrete and systematic construction of the Tardos's fingerprinting code using a chaotic map. We also introduced a. hierarchical structure to the codewords for the reduction of computational costs. However, there were room for improvement of the code-length of this structure.
In this paper, we present the optimized hierarchical structure considering appropriate parameters under the assumption that the distribution of correlation scores follows Gaussian. In a computer simulation, we evaluate the collusion-resistance of optimized Tardos code and that of original non-layered Tardos code under theoretically equal condition.

DOI： 10.1109/ISITA.2008.4895496

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

Digital fingerprinting is to embed information into multimedia contents in order to trace illegal users who distribute pirated copies. One of the serious problems in a fingerprinting system is collusion attack such that several users combine individual copies to remove/modify the embedded fingerprints. As a technique for resisting collusion attacks, Kuribayashi et. al have proposed hierarchical spread spectrum fingerprinting scheme based on the CDMA technique. In this paper, we focus on the number of IDs assigned to each layer, and adjust the assignment for each layer. By optimizing the number of IDs from the theoretical viewpoint, we can effectively decrease the number of elements to be examined, which result in the decrease of the number of false-positive detection without degrading collusion resistance.

DOI： 10.1109/ISITA.2008.4895498

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

Digital fingerprinting is used to trace back illegal users, where unique ID known as digital fingerprints is embedded into a content before distribution. On the generation of such fingerprints, one of the important properties is collusion-resistance. Binary codes for fingerprinting with a code length of theoretically minimum order were proposed by Tardos, and the related works mainly focused on the reduction of the code length were presented. In this paper, we present a concrete and systematic construction of the Tardos's fingerprinting code using a chaotic map. Using a statistical model for correlation scores, a proper threshold for detecting colluders is calculated. Furthermore, for the reduction of computational costs required for the detection, a hierarchical structure is introduced on the codewords. The collusion-resistance of the generated fingerprinting codes is evaluated by a computer simulation.

DOI： 10.1109/MMSP.2008.4665174

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

One of the serious problems in a fingerprinting system is the collusion attack such that several users combine their copies of a same content to modify/delete the embedded fingerprints. In IWSEC2007, we have proposed a collusion-resilient fingerprinting scheme based on the CDMA technique. In this paper, we formalize the model of collusion from the viewpoint of a communication channel, and design an effective detector considering the hierarchically embedded signals as a fingerprint.

DOI： 10.1109/ICME.2008.4607443

Web of Science

researchmap

出版者・発行元：IEEE  

researchmap

その他リンク： http://dblp.uni-trier.de/db/conf/eusipco/eusipco2008.html#conf/eusipco/KuribayashiM08

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：一般社団法人情報処理学会  

ディジタルコンテンツを提供する情報関連サービスにおいて，コンテンツの利用を期間限定とする時限付き鍵管理システムが考案されている．短いビット系列で長い有効期間を実現させるためには，カオス写像を用いる方式では有効期間を離散値に，木構造を用いる方式では冗長な時間鍵を与えなければならなかった．本論文では木構造を用いる方式に改良を加え，一方向性関数の特性を利用する方式を提案する．その結果，短いビット系列で長い有効期間を実現でき，特定の条件が揃わない限りは冗長性のない任意の有効期間を設定することできる．On a broadcast-type contents distribution, a time-limited key management scheme has been proposed, which enables a broadcaster to provide contents to each user with each period. In order to realize a long expiration date with a short bit-sequence, chaotic map based schemes must design the allowable period by discrete values and tree-structured schemes must allow a user for the access of extra period. In this paper, based on tree-structured scheme we propose a new time-limited key management scheme applying one-way function. In this scheme, we realize a long expiration date with a short bit-sequence, and make it possible to design arbitrary expiration date without redundancy unless a specific condition is satisfied.

CiNii Article

CiNii Books

researchmap

その他リンク： http://id.nii.ac.jp/1001/00009831/

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER-VERLAG BERLIN  

Digital fingerprinting is a scheme to insert user's own ID information into digital contents in order to identify illegal users who distribute unauthorized copy. One of the important problems is a collusion attack such that several users combine their copies of a same content to modify/delete the embedded fingerprint. In this paper, we propose a collusion-resilient fingerprinting scheme based on the CDMA technique. By combining spread spectrum sequence with orthogonal transform, we allocate the combination of spectrum components to users as their fingerprints. At a detector side, a threshold for the detection of colluded users is determined considering the false positive probability. We then estimate the parameters in the scheme for both optimal embedding and detection, and improve the accuracy of the detection of colluders. Experimental results show the effectiveness of proposed scheme.

DOI： 10.1007/978-3-540-75651-4_3

Web of Science

researchmap

掲載種別：研究論文（国際会議プロシーディングス）  

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

For the construction of a large fingerprinting system, conventional protocols need many computations to provide each fingerprinted contents to each user. In order to reduce the computational cost, we introduce a new concept of distributed providers in the fingerprinting protocol. Before a sale. our practical fingerprinting protocol using a concept of secure oblivious transfer is performed between a contents supplier and each provider. Then each provider obtains fingerprinted contents such that each bit of fingerprinting information is embedded in each segment of the contents. When a user orders some contents to the supplier, each segment of the contents is distributed from each provider specified by the supplier. The selection of providers who distribute the segments of contents is executed based on the user's identity so that the sequence of embedded bits in the collected segments may indicate the user's identity.

DOI： 10.1093/ietfec/e89-a.10.2597

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

The homomorphic property of the public key cryptosystem has been exploited in order to achieve asymmetric fingerprinting such that only a buyer can obtain fingerprinted content. However, this requires many computations and a wide-band network channel because the entire uncompressed content must be encrypted based on the public key cryptosystem. In this paper, instead of the homomorphic property, we introduce the management of the enciphering keys for the symmetric cryptosystem. Based on a buyer's identity, a trusted center issues the buyer a partial sequence which is one of the two elements in the entire sequence. Although a merchant shares the entire sequence with the center, he cannot extract the buyer's key sequence from it. Such an information gap enables our protocol to be asymmetric and efficient. For each packet of content, the merchant produces two marked packets that contains a "0" or '"1" information bit, and they are enciphered using the two elements from the entire sequence. Subsequently, the buyer obtains the two ciphertexts (the encrypted marked packets) containing the information bits of his identity. Since the merchant does not know the ciphertext decrypted by the buyer, an asymmetric property is achieved. In our protocol, before trade between a buyer and a merchant, the merchant can produce and compress the marked packets; this enables the reduction of both the computational costs for the encryption and the amount of data for transmission. Since only the enciphering operation is performed by a merchant in the on-line protocol, real-time operation may be possible.

DOI： 10.1093/ietfec/e89-a.4.1108

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

Homomorphic property of public-key cryptosystems is applied for several cryptographic protocols, such as electronic cash, voting system, bidding protocols, etc. Several fingerprinting protocols also exploit the property to achieve an asymmetric system. However, their enciphering rate is extremely low and the implementation of watermarking technique is difficult. In this paper, we propose a new fingerprinting protocol applying additive homomorphic property of Okamoto-Uchiyama encryption scheme. Exploiting the property ingenuously, the enciphering rate of our fingerprinting scheme can be close to the corresponding cryptosystem. We study the problem of implementation of watermarking technique and propose a successful method to embed an encrypted information without knowing the plain value. The security can also be protected for both a buyer and a merchant in our scheme.

DOI： 10.1109/TIP.2005.859383

Web of Science

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER-VERLAG BERLIN  

A reversible watermarking algorithm with large capacity has been developed by applying the difference expansion of a generalized integer transform. In this algorithm, a watermark signal is inserted in the LSB of the difference values among pixels. In this paper, we apply the prediction errors calculated by a predictor in JPEG-LS for embedding a watermark signal, which contributes to increase the amount of embedded information with less degradation. As one of the drawbacks discovered in the above conventional method is a large size of the embedded location map introduced to make it reversible, we decrease the large size of the location map by vectorization, and then modify the composition of the map using the local characteristic in order to enhance the performance of JBIG2.

DOI： 10.1007/11602897_37

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER-VERLAG BERLIN  

A reversible watermarking algorithm with large capacity has been developed by applying the difference expansion of a generalized integer transform. In this algorithm, a watermark signal is inserted in the LSB of the difference values among pixels. In this paper, we apply the prediction errors calculated by a predictor in JPEG-LS for embedding a watermark signal, which contributes to increase the amount of embedded information with less degradation. As one of the drawbacks discovered in the above conventional method is a large size of the embedded location map introduced to make it reversible, we decrease the large size of the location map by vectorization, and then modify the composition of the map using the local characteristic in order to enhance the performance of JBIG2.

DOI： 10.1007/11602897_37

Web of Science

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER-VERLAG BERLIN  

Fingerprinting protocol applies a watermarking techniques to embed a fingerprinting information in a digital content such as music, image, movie, etc.. The cryptographic protocol is studied by many researchers, but how to apply watermarking techniques is not remarked. In this paper, we study the problem to implement the watermarking techniques in the fingerprinting protocol, and then propose an ingenious method to embed a fingerprinting information in a digital image. The alteration of the embedded information is difficult for a hostile buyer in our scheme.

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER-VERLAG BERLIN  

Fingerprinting protocol applies a watermarking techniques to embed a fingerprinting information in a digital content such as music, image, movie, etc.. The cryptographic protocol is studied by many researchers, but how to apply watermarking techniques is not remarked. In this paper, we study the problem to implement the watermarking techniques in the fingerprinting protocol, and then propose an ingenious method to embed a fingerprinting information in a digital image. The alteration of the embedded information is difficult for a hostile buyer in our scheme.

DOI： 10.1007/978-3-540-24624-4_43

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

One of the important topics of watermarking technique is a robustness against geometrical transformations. In the previous schemes, a template matching is performed or an additional signal is embedded for the recovery of a synchronization loss. However, the former requires the original template, and the latter degrades the quality of image because both a watermark and a synchronization signal must be embedded. In the proposed scheme only a synchronization signal is embedded for the recovery of both a watermark and a synchronization loss. Then the embedded information depends on the distance between two embedded signal positions. The distance is not changed seriously by random geometrical transformations like StirMark attack unless the embedded signal is disturbed. Therefore, a watermark can be extracted correctly from such geometrically transformed image if the synchronization signal can be recovered.

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SCRIPTA TECHNICA-JOHN WILEY & SONS  

In general, a signal embedded in the low-frequency components of an image is less likely to be affected by attack. However, there is a problem of substantial degradation of image quality. In particular, if each divided block is processed, the blocking effects generated between adjacent blocks is more easily perceived. In this paper, an embedding method without blocking effects is proposed, making effective use of the superposition of the low-frequency components in the two-dimensional DCT basis images. Due to the effect of superposition of the two-dimensional DCT bases, the watermark information is not detected directly from the block with embedding, but extraction is performed from the subblocks in the block. In the proposed method, in order to provide robustness against geometrical transformation, the synchronization is recovered prior to extracting the watermark information. The robustness can be further enhanced by means of error correcting code. (C) 2003 Wiley Periodicals, Inc.

DOI： 10.1002/ecjc.10048

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Generally, the wavelet transform is applied for watermarking, where a whole image is transformed to the frequency domain. However, many schemes which adopt the wavelet transform are weak for StirMark attack designed to affect locally such as rotation, extension, reduction, etc. In this paper, we propose a new scheme which applies the wavelet transform locally and has a tolerance for StirMark attack. How to maintain the quality of the watermarked image is also shown.

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER-VERLAG BERLIN  

Generally, low frequency domain may be useful to embed a watermark in an image. However, if a watermark is embedded into low frequency components, blocking effects may occur in the image. Then considering blocking effects, we study some characteristics among DCT coefficients and find some interesting mutual relations. Here, the robustness of many schemes based on the orthogonal transformations such as DCT may be doubtful against geometric transformations. For the distortions produced by some geometric transformations, we propose a searching protocol to find the watermarked block which is rotated and shifted. In the proposed scheme, a watermark can remain in the attacked image with very high probability in our scheme. Further, the watermark becomes more robust than the above scheme using error-correction.

DOI： 10.1007/3-540-44456-4_1

Web of Science

researchmap

出版者・発行元：Springer  

DOI： 10.1007/3-540-45311-3_3

CiNii Article

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

その他リンク： https://dblp.uni-trier.de/rec/conf/apsipa/2021

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

その他リンク： https://dblp.uni-trier.de/rec/conf/apsipa/2021

J-GLOBAL

researchmap

記述言語：日本語   出版者・発行元：日本音響学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：映像情報メディア学会  

CiNii Article

CiNii Books

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

記述言語：日本語  

CNNを用いた画像分類器の研究が盛んに進められている一方で，その画像分類器を欺くことができる敵対的事例の存在が指摘されている．敵対的事例とは，意図的に造られた小さな摂動を元の画像に加えることで，画像分類器の識別結果が元の画像と異なるクラスを指す画像である．人間の目では元の画像との差異を判別することが困難であるため，敵対的事例を検知することが一般的には難しい．本研究では，敵対的事例と正常な画像を識別することを目的とする．画像分類器が誤った結果を出力する理由は，敵対的事例の微小なノイズが影響しているためである．提案手法では，ノイズ除去を目的としてJPEG圧縮によるフィルタ処理をすることで，画像分類器の識別結果の変動を解析する．JPEG圧縮の品質パラメータの変化に伴う識別結果の違いを特徴成分として，単純なしきい値を用いることにより敵対的事例と正常な画像を高精度で識別することができた．
While the research on image classifiers using CNN has been actively investigated, the study of adversarial example which can fool the image classifiers has been a potential threat in this research field. The adversarial example is created by intentionally adding small perturbations to an image so that an image classifier identifies a different class from the original class. It is not easy to detect adversarial example because the human eye cannot distinguish the difference from the original image. The objective of this study is to distinguish adversarial examples from natural images. The reason why an image classifier outputs an incorrect result is the tiny noise added to an original image. In this study, we analyse the fluctuation of the classification result by filtering with JPEG compression for the purpose of noise removal. By using a simple threshold, it is possible to discriminate adversarial examples and natural images with high accuracy from the characteristics of the fluctuations.

CiNii Article

researchmap

記述言語：日本語  

撮影されただけのオリジナル画像は通常，JPEG圧縮が1回行われている．一方，改ざんされた画像は再度圧縮が行われ2重圧縮となる．そこで，画像から2重圧縮の特徴を抽出し，ニューラルネットワークで分類することによって，画像の改ざんを検知する方法を本研究では扱う．その特徴は，1回目と2回目のJPEG圧縮時における量子化テーブルの相違により，DCT係数値の統計的な頻度分布の偏りとして現れる．本研究では，量子化テーブルの特徴を考慮した2重JPEG圧縮を検知する方式を提案する．1回目の圧縮時に量子化する際の品質パラメータ(QF)が2回目の圧縮時より大きい場合，DCT係数の頻度分布の値が偏る．その特徴を検知するために，量子化テーブルにおいて収集しやすいDCT係数値を複数扱う．収集したDCT係数値の頻度分布を入力とし，畳み込みニューラルネットワーク(CNN)に学習させることで，1回圧縮と2重圧縮を分類する．
Detection of double JPEG compression plays an important role in digital forensics. As we can find some clues from a given image about the history of JPEG compression, it is possible to classify the image if it is tampered or not. The characteristic of double compression appears at the statistical distribution of histogram in DCT coefficients because of quantization with different QFs. Unfortunately, such characteristics in the histogram are distorted by the rounding operation occurred at the process of decompression. In this study, considering the value of quantization table, we select some of them to collect useful statistical information as possible. We propose a CNN-based classifier suitable for the analysis of this histogram in order to classify a given image into single compression or double compression.

CiNii Article

researchmap

記述言語：日本語  

電子指紋符号に対して結託攻撃を行った結託者を検出する最適な検出器が提案されている．しかし，この検出器では，結託攻撃戦略と結託者数の情報が必要となる．従来研究では，符号語のシンボルの偏りに注目することでパラメータを高精度で推定し，最適な検出器に近い性能を達成している．一方で，複数の結託者を検出するために符号語生成用パラメータの値が増加した場合，この推定器では推定のためのベクトル空間の次元が増加することが考えられる．本研究では，推定に必要な特徴ベクトルのドミナントな成分に着目し，ベクトル空間の次元の増加に依存せず一定の次元で推定が行えるように，推定のための高次元ベクトル空間の次元削減法を提案する．また，従来研究で考慮されていなかった，異なる符号語生成パラメータでの推定器を実装し，計算機シミュレーションによって検出性能の比較を行った．計算機シミュレーションの結果，次元削減を行った状態でも高い性能を達成し，最適な検出器に近い性能を有することが確認できた．
The optimal detector against colluders in fingerprinting codes has been proposed.However, this detector requires information about the collusion attack strategy and the number of colluders.In the previous studies, the estimator using the bias of symbols of codewords made it possible to estimate these parameters with high accuracy and the performance of detection almost achieved the optimal detector.On the other hand, assuming multiple colluders attack and the parameter for generation of codewords is increased, it may be necessary to reduce dimensions for estimation because it depends on the parameters for generation.This study shows a detector for large colluders using low dimension estimator which uses dominant features and the computational simulation compared with previous studies.As a result of simulation, it reveal that our proposed detector reached the optimal detector and previous estimator without a large scale dimension.

CiNii Article

researchmap

記述言語：日本語  

本グループでは，Javaプログラミング教育の高度化を狙いとして，Webを用いたJavaプログラミング学習支援システムJPLASを開発している．JPLASでは，学習者の作成した解答コードに対し，テストコードを用いたソフトウェアテストによる自動採点を行っている．その際，学習者は，テストコード中の情報（クラス，メソッド，変数の名称，アクセス修飾子，データ型など）を読み取り，解答コードに反映する必要がある．そのため，テストコードと誤りのある問題コードを与え，後者の修正を求める，コード修正問題を提案している．また，問題コード生成のために，ソースコードに誤りを施すアルゴリズムを提案している．本研究では，コード修正問題において，1)問題コードの多様化のための誤り情報の追加，2)テストコードを用いた問題コードの検証による正当性検証，3)問題コードの難易度の制御機能，の3つの改良を提案する．それらをJPLASに実装し，本学科Javaプログラミング授業での利用により，本提案の有効性を検証する．
To enhance Java programming educations, we have developed the Web-based Java Programming Learning Assistant System (JPLAS). JPLAS automatically marks the answer code of a student through software test using the test code. Thus, a student has to extract the necessary information from the test code to implement the answer code. To help a novice student, we proposed the code correction problem in the previous study, where a source code with errors, called a problem code, is given to a student with a test code, and is requested to be corrected to pass the test. We also proposed the algorithm to generate the problem code by making errors in the source code. In this study, we propose three improvements in the code correction problem: 1) to allow additional code items for errors for variation of the problem code, 2) to verify the correctness of the problem code by testing it, and 3) to implement the problem difficulty control function. We verify the effectiveness through applications in the Java programing course in our department.

CiNii Article

CiNii Books

researchmap

記述言語：日本語  

Javaは，可搬性，堅牢性，安全性に優れたプログラミング言語として，業務系システム，組み込みシステムなどに幅広く利用されており，そのプログラミング教育が重要である．そこで本研究室では，Webを用いたJavaプログラミング学習支援システムJPLAS（Java Programming Learning Assistant System）を開発し，授業での運用を行っている．現状のJPLASでは，教員がそれぞれの学生の問題解答状況を一覧で把握するための機能を有していない．また，全学生に同一の問題が出されており，個々の学生の学習レベルに適した問題が出題されていない．本発表では，以上の課題を解決するために，JPLASにおいて，エレメント補充問題を対象として，学生の解答状況の可視化機能，および，各学生に次に解くべき問題の推薦機能を実装する．特に後者では，これまでの学生の解答結果の分析により，各問題の難易度の算出法を提案し，各学生の解答履歴から，その学生に適した難易度の問題を次に解くべき問題として推薦する．評価として，教員に対して，解答状況可視化機能を用いたプログラミング演習を行ってもらう．また，学生に対して，問題推薦機能を用いた問題演習を行ってもらう．その後，アンケートの実施および解答結果の分析を行い，有効性を検証する．今後の課題として，問題難易度設定方法の再検討，エレメント補充問題以外の問題も対応可能な問題推薦機能への拡張があげられる．
As a portable, solid, secure programming language, Java is used widely such as business system and embedded system, thus its programming education is important. Therefore, we have developed the Web-based Java Programming Learning Assistant System (JPLAS) and used it in the Java programming course. JPLAS has no function which teacher can follow answering status of problems for each student. Additionally, it set the same problems to all of students, thus, it doesn't set the suitable problems corresponding to learning level for each student. In this presentation, we implement the answering status visualization function for each student and the recommendation function which recommend problems each student should solve the next for element fill in blank problems in JPLAS. In particular in the latter one, according to analysis of students' answering results so far, we propose the calculation method of problem difficulty and the system recommend the suitable problem to solve the next with learning level and answering history of each student. As an evaluation, we apply the answering status visualization function to the teacher in the programming exercise. Furthermore, we inspect the effectiveness by conducting a questionnaire survey and analyzing the answering results after students solve some of problems using problem recommendation function. In the future works, revision of the way to set up the problem level of difficulty and extension of problem recommendation function to follow other type of problems are some important tips.

CiNii Article

CiNii Books

researchmap

記述言語：英語  

CiNii Article

CiNii Books

researchmap

担当区分：筆頭著者,　責任著者   記述言語：英語  

担当区分：筆頭著者,　責任著者   記述言語：英語  

担当区分：筆頭著者,　責任著者   記述言語：英語  

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

記述言語：英語  

記述言語：英語  

記述言語：英語  

記述言語：英語  

記述言語：日本語   出版者・発行元：日本音響学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：日本音響学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語  

記述言語：日本語   出版者・発行元：映像情報メディア学会  

CiNii Article

CiNii Books

researchmap

記述言語：英語  

記述言語：英語  

記述言語：英語  

記述言語：英語  

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：英語  

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：英語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

J-GLOBAL

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

J-GLOBAL

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

J-GLOBAL

researchmap

J-GLOBAL

researchmap

記述言語：英語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：英語   出版者・発行元：Graphy Publications  

For advancements of Java programming educations, we have developed a Web-based Java Programming Learning System (JPLAS). JPLAS provides four problems with different levels, namely, element fill-inblank problem, value trace problem, statement fill-in-blank problem, and code writing problem, to cover students at different learning stages. Unfortunately, since JPLAS has been implemented by a number of students who studied in our group at different years, the code has become complex and redundant, which makes further extensions of JPLAS extremely hard. In this paper, we propose a software architecture for JPLAS to avoid redundancy. Based on the MVC model, our proposal uses Java for the model (M), HTML/CSS/JavaScript for the view (V), and JSP for the controller (C). Besides, adopting a design pattern, the marking functions of the four problems are implemented uniformly. For evaluations, after JPLAS is implemented with this architecture, the number of code files is compared with that of the previous implementation, and the number of additional files is examined for two new functions.

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

researchmap

記述言語：日本語  

J-GLOBAL

researchmap

J-GLOBAL

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：英語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：英語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：英語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：英語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：英語   出版者・発行元：電子情報通信学会  

CiNii Article

CiNii Books

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap

記述言語：日本語   出版者・発行元：電子情報通信学会  

CiNii Article

researchmap