International Journal of Networking and Computing
Online ISSN : 2185-2847
Print ISSN : 2185-2839
ISSN-L : 2185-2839
10 巻 , 2 号
選択された号の論文の18件中1~18を表示しています
Special Issue on the Seventh International Symposium on Computing and Networking
  • Koji Nakano
    2020 年 10 巻 2 号 p. 61
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    The Seventh International Symposium on Networking and Computing (CANDAR 2019) was held in Nagasaki, Japan, from November 26th to 29th, 2019. The organizers of the CANDAR 2019 invited authors to submit the extended version of the presented papers. As a result, 21 articles have been submitted to this special issue. This issue includes the extended version of 17 papers that have been accepted. This issue owes a great deal to a number of people who devoted their time and expertise to handle the submitted papers. In particular, I would like to thank the guest editors for the excellent review process: Professor Hideharu Amano, Professor Akihiro Fujiwara, Professor Ikki Fujiwara,Professor Sayaka Kamei, Professor Susumu Matsumae, Professor Toru Nakanishi, Professor Yasuyuki Nogami, Professor Kouzou Ohara,Professor Tomoyuki Ohta, and Professor Minoru Uehara. Words of gratitude are also due to the anonymous reviewers who carefully read the papers and provided detailed comments and suggestions to improve the quality of the submitted papers. This special issue would not have been without their efforts.
  • Paola Flocchini, Eman Omar, Nicola Santoro
    2020 年 10 巻 2 号 p. 62-83
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    As most existing sensors are powered by batteries, the coverage provided by a sensor network degrades over time and eventually disappears if energy is not restored. A popular approach to energy restoration is to use a robot acting as a mobile battery charger/changer. The robot decides where to move next according to a predefined on-line energy restoration strategy. The effectiveness of such a strategy depends on the number of nodes it is able to maintain operational at any given time, as well as on for how long a node whose battery is depleted remains non-operational. The ideal optimal on-line strategy (called OPTIMAL) occurs when the robot knows at any time the current status of all sensors, and it computes the best request to satisfy next, based on this information. Although optimal in terms of effectiveness, this centralized strategy would constantly require up-to-date global information; hence its high computational and communication costs make it not feasible. We consider a drastically different on-line strategy (called LIC), which is simple and fully decentralized, uses only local communication, requires no computations, and is highly scalable. In our strategy, the robot visits the sensors in a predefined circular order, moving in a "clockwise" direction and only when aware of a pending request. A sensor whose battery is about to become depleted originates a recharging request and waits for the robot; the request is forwarded according to the circular order in a "counter-clockwise" direction until it reaches either the robot or another sensor waiting for the robot. We show the perhaps unexpected result that, once the system becomes stable, in most networks the effectiveness of LIC is equivalent to that of OPTIMAL. In other words, in most cases, in spite of its simplicity and its extremely small (communication and computation) costs, the proposed decentralized strategy is as effective as the optimal centralized one. We augment our theoretical results with experimental analysis, confirming all the analytical results and showing among other things that the system stabilizes very quickly.
  • Yuki Hirayama, Tetsuya Asai, Masato Motomura, Shinya Takamaeda
    2020 年 10 巻 2 号 p. 84-93
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    The main problems of deep learning are requiring a large amount of data for learning, and prediction with excessive confidence. A Bayesian neural network (BNN), in which a Bayesian approach is incorporated into a neural network (NN), has drawn attention as a method for solving these problems. In a BNN, the probability distribution is assumed for the weight, in contrast to a conventional NN, in which the weight is point estimated. This makes it possible to obtain the prediction as a distribution and to evaluate how uncertain the prediction is. However, a BNN has more computational complexity and a greater number of parameters than an NN. To obtain an inference result as a distribution, a BNN uses weight sampling to generate the respective weight values, and thus, a BNN accelerator requires weight sampling hardware based on a random number generator in addition to the standard components of a deep learning neural network accelerator. Therefore, the throughput of weight sampling must be sufficiently high at a low hardware resource cost. We propose a resource-efficient weight sampling method using inversion transform sampling and a lookup-table (LUT)-based function approximation for hardware implementation of a BNN. Inversion transform sampling simplifies the mechanism of generating a Gaussian random number from a uniform random number provided by a common random number generator, such as a linear feedback shift register. Employing an LUT-based low-bit precision function approximation enables inversion transform sampling to be implemented at a low hardware cost. The evaluation results indicate that this approach effectively reduces the occupied hardware resources while maintaining accuracy and prediction variance equivalent to that with a non-approximated sampling method.
  • Atsushi Ito, Kai Takahashi
    2020 年 10 巻 2 号 p. 94-110
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    In Japan, there is a high chance of getting damage from earthquakes, tsunamis, and typhoons, so we need to get information about where to evacuate quickly. However, in such situations, communication infrastructures such as base stations of 3G, LTE are broken. Even if they are available, many people try to access the Internet or make a phone call, network congestion occurs. As a result, their ways of communication are limited. Under such a situation, weak people at a disaster, who called CHECT (Children, Handicapped, Elderly people, Chronically ill, Tourists), usually receive a disadvantage. We have been developed a support system for hearing-impaired people in a disaster since 2007 because they are hard to get information because a lot of emergency information is delivered by sound. For them, information by vision is more suitable. Now, we are testing our disaster information delivery system in Miyagi-Prefectural School for the Deaf. The system is constructed by several LED displays and connected by the ad-hoc network. To install our system, we are now trying to use Bluetooth Low Energy (BLE) Advertisement. In this paper, we will explain the outline of our system and the result of the experiment of the performance of the ad-hoc network with BLE Advertisement. The performance includes the reachability of transmitted packets, the routability of the routing protocol we developed. As a result, we can conclude that BLE Advertisement based ad-hoc network is feasible to construct a disaster information system for hearing-impaired people.
  • Yang Sun, Guan-Shen Fang, Sayaka Kamei
    2020 年 10 巻 2 号 p. 111-126
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    In many online review sites or social media, each user is encouraged to assign a numeric rating and write a textual review as a feedback to each item that he had gotten, e.g., a product that he had bought, a place that he had visited, a service that he had received. Sometimes, feedbacks by some users would be affected by some contextual factors such as weather, distance, time, and season. Therefore, the context-aware approach is being developed by utilizing the user's contextual information to produce more precise recommendations than traditional approaches. Furthermore, previous works have already approved the drawback of the ignorance of textual reviews would bring mediocre performance for rating prediction. In this work, we propose a framework TF+ for rating prediction models based on Tensor Factorization (TF) which is an extended version of Matrix Factorization (MF) by adding another dimension. We consider seasonal context as the additional dimension. Firstly, in our framework, each of the reviews is characterized by a numeric feature vector. Secondly, it uses TF which is trained by the proposed first-order gradient descent method for TF named Feature Vector Gradient Descent (FVGD). For the training of TF in TF+, FVGD decides the learning rates based on the feature vectors of reviews. In our evaluation, we use pre-processed data of five cities in YELP challenge dataset, and apply one of LDA, Doc2Vec and SCDV to get numeric feature vectors of reviews. We conduct experimental comparisons, and the results show that methods by TF+ improve the performance significantly as compared to the basic TF model.
  • Kazuichi Oe, Takeshi Nanri
    2020 年 10 巻 2 号 p. 127-143
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    Automated tiered storage with fast memory and slow flash storage (ATSMF) is a hybrid storage system located between non-volatile memories (NVMs) and solid state drives (SSDs). ATSMF reduces the average response time for input-output (IO) accesses by migrating concentrated IO-access areas from an SSD to an NVM. However, the current ATSMF implementation cannot sufficiently reduce the average response time because of the bottleneck caused by the Linux brd driver, which is used for the NVM access driver. The response time of the brd driver is more than ten times longer than memory-access speed. To sufficiently reduce the average response time, we developed a block-level driver for an NVM called a "two-mode (2M) memory driver." This driver has a .map-access mode and direct-access mode to reduce the response time while maintaining compatibility with the Linux device-mapper framework. The direct-access mode has a drastically lower response time than the Linux brd driver because the ATSMF driver can directly execute the IO-access function of the 2M memory driver. Experimental results indicate that ATSMF using the 2M memory driver reduced the IO access response time to less than that of ATSMF using the Linux brd driver in most cases.
  • Keiji Yoshimoto, Yoshinori Uetake, Yuta Kodera, Takuya Kusaka, Yasuyuk ...
    2020 年 10 巻 2 号 p. 144-158
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    IoT devices contribute to improving the mechanism of a system as edge devices for data sharing and automation of industrials. However, such devices are often being a target of an attacker due to their simple architecture and the lack of resources so as to protect data confidentiality using cryptosystems. In addition, although Curve25519 has been used in various security protocols and known to work even on IoT devices efficiently, the curve inherits the low order points hidden inside of the Edward curves. In this paper, the authors demonstrate side-channel attacks against Curve25519 by focusing on the points of order 4 and 8. We choose the order 4 point which does not exist on Curve25519, that exists on the twisted curve of Curve25519. More precisely, the rational point used in this paper is given by (x,y)=(-1,0) in affine coordinates. In addition, the order 8 point appears to be a high order rational point. The results reveal that the rational points might be a threat to key extraction and it demands us to find further countermeasures.
  • Kotaro Umetsu, Akihiro Fujiwara
    2020 年 10 巻 2 号 p. 159-173
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    Membrane computing is a computational model based on activity of cells. Using the membrane computing, a number of computationally hard problems have been solved in a polynomial number of steps using an exponential number of membranes. However, the number of membranes denotes the number of cells from practical point of view, and the reduction of the number of membranes must be considered for using the membrane computing in real world. In this paper, we propose asynchronous P systems with branch and bound for reducing the number of membranes for two computationally hard graph problems. We first propose an asynchronous P system that solves Hamiltonian cycle problem for a graph with n vertices, and show that the proposed P system works in O(n^2) parallel steps. We next propose an asynchronous P system that solves the minimum graph coloring for a graph with n vertices, and also show that the P system works in O(n^2) parallel steps. In addition, we evaluate validity of the proposed P systems using computational simulations. The experimental results show the validity and efficiency of the proposed P systems with branch and bound.
  • Hiroshi Okano, Keita Emura, Takuya Ishibashi, Toshihiro Ohigashi, Tats ...
    2020 年 10 巻 2 号 p. 174-188
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    Identity-based encryption (IBE) is a powerful mechanism for maintaining security. However, systems based on IBE are unpopular when compared with those of the public-key encryption (PKE). In our opinion, one of the reasons is a gap between theory and practice. For example, a generic transformation of weakly/strongly robust IBE from any IBE has been proposed by Abdalla et al., no robust IBE scheme is explicitly given. This means that, theoretically, anyone can construct a weakly/strongly robust IBE scheme by employing this transformation. However, this seems not easily applicable to non-cryptographers. In this paper, we first introduce the Gentry IBE scheme constructed over Type-3 pairings by employing the transformation proposed by Abe et al., and second we explicitly give strongly/weakly robust Gentry IBE schemes by employing the Abdalla et al. transformation. Finally, we show its implementation result and show that we can add strong robustness to the Gentry IBE scheme with a very few additional costs. We employ the mcl library to support a Barreto-Naehrig curve defined over the 462-bit prime. The encryption requires about 5 ms, whereas the decryption requires about 9 ms.
  • Rie Shigetomi YAMAGUCHI, Toshiyuki Nakata, Ryosuke Kobayashi
    2020 年 10 巻 2 号 p. 189-199
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    While the use of intelligent devices such as smartphones is spreading rapidly, for the most part, people continue to rely on old ID/password methods for authentication purposes, and the modernization of authentication technology is recognized as an ongoing challenge for society. In the face of this challenge, one form of authentication technology that has been attracting significant attention recently promotes the use of information technology (IT) to identify people based on information about their habits. In application, this technology obtains information about users from smartphones and wearable devices and thus performs authentication without requiring them to perform any verification operations. This is accomplished by redefining and organizing a fourth personal authentication factor, behavior. Herein, we discuss the recent trends of this technology as part of smartphone society, define the technical issues that must be resolved for realizing behavior authentication, and describe measures for resolving them.
  • Jubee Tada, Ryosuke Higashi
    2020 年 10 巻 2 号 p. 200-212
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    In recent computer systems, a high-performance memory system is required for improving the computing performance. To improve the performance of the memory system, the capacity and the associativity of cache memories tend to be enlarged in all the memory hierarchy. Therefore, a high-performance cache replacement policy is required, which can be implemented with a small overhead and can adapt the behavior of various applications. Under such a situation, the adaptive demotion policy with considering global fluctuations of priority values (ADP-G) is proposed. ADP-G is based on the adaptive demotion policy (ADP) which can adapt the behavior of various applications by changing its insertion, promotion, demotion and selection (IPDS) policies. ADP-G selects the appropriate IPDS policies from two alternatives, one is suitable for a temporal locality and the other has a scan/thrashing tolerant. For this selection, ADP-G uses the global fluctuations of priority values of all the blocks in the cache. Although ADP-G is a high-performance cache replacement policy as compared with conventional ones, it causes a problem when the performance of the scan/thrashing tolerant IPDS policies is higher than that of the temporal locality IPDS policies. This paper discusses a novel cache replacement policy to solve this problem. At first, the fluctuation patterns of total priority value in several benchmarks are analyzed. As a result, two characteristics are observed which are useful to detect that the running application the suitable for the temporal locality IPDS policies or the scan/thrashing tolerant IPDS policies. Based on this analysis, a cache replacement policy with considering fluctuation patterns of total priority value is proposed, and it is called ADP-P. ADP-P has two states which suitable for the temporal locality and the scan/thrashing tolerant. To detect the suitable state, ADP-P uses the total of the priority values of all the blocks in the cache, and the value is stored in the global total register (GTR). When the state is for the temporal locality, the state is changed to the scan/thrashing tolerant state if the reduction of GTR is larger than the threshold value. When the state is for the scan/thrashing tolerant, the state is changed to the temporal locality state if the fluctuation of GTR which is larger than the threshold value is not caused for a fixed number of cache accesses. Experimental results show the proposed cache replacement policy achieves a reduction of cache misses compared to LRU policy and ADP-G. When the L3 cache size is 4MB, in the geometric mean of all the benchmarks, the proposed cache replacement policy achieves a 6.0% and 11% MPKI reduction compared to ADP-G and LRU policy, respectively.
  • Zhao Hao, Yaokai Feng, Hiroshi Koide, Kouichi Sakurai
    2020 年 10 巻 2 号 p. 213-226
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    With rapidly increasing cyber attacks, network security has become an important issue. To protect ourselves against cyber attacks, the Intrusion Detection System (IDS) has been introduced. In such systems, different kinds of machine learning algorithms play a more and more important role, such as support vector machine(SVM), artificial neural network(ANN), etc. False positive rate and false negative rate, in addition to accuracy, are widely used for the evaluation of IDSs. These indices, however, are often related to each other, which makes it is difficult for us to improve all the indices at the same time. For example, when we try to make the false negative rate decrease to prevent from missing attacks, more normal communications tend to be classified into attacks and the false positive rate may increase, and vice versa. In this study, we propose an ANN based sequential classifier method to mitigate this problem. We design each subclassifier with a low false positive rate, which may lead to high false negative rate. To decrease the false negative rate, the reported negative instances from the former subclassifier are sent to the next one to further check (reclassification). In this way, it can be expected that the false negative rate can also reach an acceptable level. The results of our experiment shows that our proposed method can bring lower false negative rate and higher accuracy, in the mean time the false positive rate is kept at an acceptable level. We also investigated the effect of the number of subclassifiers on detection performance and found that the detection system performed best when using four subclassifiers.
  • Yuki Nanjo, Masaaki Shirase, Takuya Kusaka, Yasuyuki Nogami
    2020 年 10 巻 2 号 p. 227-241
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    It is well-known that quadratic extension fields (QEFs) based on optimal extension fields (OEFs) are typically used for supersingular isogeny Diffie-Hellman (SIDH) key exchange protocol. On the other hand, there is a possibility of the performance improvement of SIDH by employing other attractive choices of QEFs with efficient performing arithmetics which are based on all-one polynomial extension fields (AOPFs) and extension fields with normal basis representation (EFNs). Thus, the authors confirm that the applicability of the new candidates of QEFs for SIDH and evaluate SIDH applied the possible choices of QEFs. As a result of the experiment, the authors found that the performances of SIDH applied the QEFs based on AOPF and EFN are comparable to that of the previous QEF. Moreover, one of the QEFs based on EFN result in a new efficient implementation of the SIDH with SIDH-friendly prime given as p= 2^{e_A}3^{e_B}f+1 where e_A, e_B and $f$ are positive integers.
  • Naoki Kamikawa, Hiroshi Umeo
    2020 年 10 巻 2 号 p. 242-258
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    A cellular automaton (CA) is a well-studied non-linear computational model of complex systems in which an infinite one-dimensional array of finite state machines (cells) updates itself in a synchronous manner according to a uniform local rule. A sequence generation problem on the CA model has been studied for a long time and a lot of generation algorithms has been proposed for a variety of non-regular sequences such as { 2^n | n = 1, 2, 3, ... }, primes, Fibonacci sequences etc. In this paper, we study a real-time sequence generation algorithm for k-th powers of natural numbers on a CA . In the previous studies, Kamikawa and Umeo (2012, 2019) showed that sequences { n^2 | n = 1, 2, 3, ...}, { n^3 | n = 1, 2, 3, ... } and { n^4 | n = 1, 2, 3, ... } can be generated in real-time by one-dimensional CA s. We extend the generation algorithm for { n^4 | n = 1, 2, 3, ... } shown by Kamikawa and Umeo, and present a generation algorithm for the sequence { n^k | n = 1, 2, 3, ... } implemented.
  • Taito Manabe, Koki Tomonaga, Koki Fujita, Yuichiro Shibata, Taiichiro ...
    2020 年 10 巻 2 号 p. 259-276
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    Laparoscopic surgery, a less invasive camera-aided surgery, is now performed commonly. However, it requires a camera assistant who holds and maneuvers a laparoscope. By controlling the laparoscope automatically using a robot, a surgeon can perform the operation without a camera assistant, which would be beneficial in areas suffering from lack of surgeons. In this paper, a prototype image segmentation architecture based on a convolutional neural network (CNN) is proposed to realize an automated laparoscope control for cholecystectomy. Since a training dataset is annotated manually by a few surgeons, its scale is limited compared to common CNN-based systems. Therefore, we built a recursive network structure, with some sub-networks which are used multiple times, to mitigate overfitting. In addition, instead of the common transposed convolution, the flip-based subpixel reconstruction is introduced into upsampling layers. Furthermore, we applied stochastic depth regularization to the recursive structure for better accuracy. Evaluation results revealed that these improvements bring better classification accuracy without increasing the number of parameters. The system shows a throughput sufficient for real-time laparoscope robot control with a single NVIDIA GeForce GTX 1080 GPU.
  • Yusuke Takemura, Keisuke Hakuta, Naoyuki Shinohara
    2020 年 10 巻 2 号 p. 277-292
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    Various side-channel attacks against elliptic curve cryptography (ECC) have been proposed so far, including simple power analysis, horizontal collision correlation analysis, improving the Big Mac attack, and differential power analysis. Developing countermeasures against such attacks is considered as an important research task in cryptography. They are executed by analyzing power consumption while a device implemented in a cryptosystem performs cryptographic processing. To address this problem, we propose using three atomic blocks serving as the countermeasures against such attacks on ECC over finite fields of characteristic two. Two of them are basic atomic blocks, while the third one is an improved version of these two, having lower computational cost. In this paper, concerning the possibility of more sophisticated side-channel attacks appearing in the future, we propose a threat model based on the atomic blocks that is constructed to be secure for strong side-channel attacks with more powerful abilities.
  • Kenta Inoue
    2020 年 10 巻 2 号 p. 293-307
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    One of the reasons why neural networks are used in machine learning is their high expressive power, that is, the ability to express functions. Expressive power of neural networks depends on its structures and is measured by some indices. In this paper, we focus on one of these measures named "expressive number", which is based on the number of data that can be expressed. Expressive numbers enable us to see whether the size of a neural network is suitable for the given training data before we conduct machine learning. However, existing works on expressive numbers mainly target single hidden layer neural networks, and little is known about those with two or more hidden layers. In this paper, we give a lower bound of the maximum expressive number of two hidden layer neural networks and an upper bound of that of multilayer neural networks with ReLU activation function. This result shows the expressive number of two hidden layer neural networks is in O(a_1a_2) where a_1 and a_2 are the numbers of each hidden layer's neurons.
  • Hiroki Furue, Dung Hoang Duong, Tsuyoshi Takagi
    2020 年 10 巻 2 号 p. 308-324
    発行日: 2020年
    公開日: 2020/07/20
    ジャーナル オープンアクセス
    At PKC 2018, Chen et al. proposed SOFIA, the first MQ-based digital signature scheme having tight security in the quantum random oracle model (QROM). SOFIA is constructed by applying an extended version of the Unruh transform (EUROCRYPT 2015) to the mathcal MQ-based 5-pass identification scheme (IDS) proposed by Sakumoto et al. (CRYPTO 2011). In this paper, we propose an MQ-based 3-pass IDS with impersonation probability of 1/2 and apply the original version of the Unruh transform to it to obtain a more efficient MQ-based digital signature scheme tightly secure in the QROM. The signature size of our digital signature scheme decreases by about 35% compared with SOFIA in the level I of NIST PQC security category, and is supposed to be the shortest among that of MQ-based signatures tightly secure in the QROM.
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