IoT malware is rapidly increasing due to variants easily generated from publicly available source codes. Malware image classification capable of fast and accurate malware identification attracts attention. Since the classification by imaging is affected by malware binary changes, a binary modification without behavioral changes can be a potential attacking method to the classification by imaging. There are concerns that by combining the publicly available malware source code with readily available source code obfuscation tools, it is possible to construct an effective attack that bypasses image classifiers relatively simply. In this study, we show the effectiveness of the attack by source code obfuscation and the possibility of defense against the attack. The contribution of this research is twofold. 1) We showed that Obfuscator-LLVM (oLLVM) code obfuscation could be used as an attack method on malware image classification. The obfuscated malware binaries made by oLLVM were misclassified by VGG16-based image classifier for all the attacked malware families including Mirai, Lightaidra, and Bashlite. 2) We showed that classifier training with obfuscated samples could address this attack method. We confirmed that the malware image classifier trained with obfuscated malware binaries made by oLLVM could classify with an accuracy of 100% the malware family with obfuscation as the obfuscated original malware family.

Internet of Things (IoT) systems are of paramount importance to provide ubiquitous wireless connectivity for smart cities. However, such systems are facing security challenges due to the broadcast and openness nature of wireless channels. This article studies the performance of covert communication under a scenario consisted of a source-destination pair, a passive warden, and multiple relays. We first propose two relay selection schemes, one is random selection and another is superior-link selection. Based on these two schemes, we then examine the transmission strategy design for the source and thus define the necessary condition that the source can transmit covert messages. We further derive the detection error probability of warden and covert capacity based on two relay selection schemes and also explore the covert capacity maximization through efficient numerical searches. Finally, numerical results are provided to illustrate our theoretical findings and the performance of covert communication in such systems. Remarkably, the superior-link selection scheme has 108% improved to the random selection scheme for the maximum covert capacity performance under the same transmission power at the source.

In Japan, early warnings such as the earthquake early warning and the tsunami warning are broadcast to cellular phones by using the Earthquake and Tsunami Warning System (ETWS) [1]. The connectivity of a LTE device (UE: user equipment) depends on the LTE base station (evolved Node B: eNB) which acts as a relay with the Internet. Therefore it is difficult to broadcast early warnings during large-scale disasters.

This paper investigates the security-delay trade-off of the buffer-aided relay selection scheme in a two-hop wireless system, which consists of a source-destination pair, one eavesdropper, and multiple relays each having a finite buffer. To evaluate the security and delay performances of the system, we derive analytical expressions for the end-to-end (E2E) secure transmission probability (STP) and the expected E2E delay under both perfect and partial eavesdropper channel state information (CSI) cases. These analytical expressions help us to explore the inherent trade-off between the security and delay performances of the concerned system. In particular, the results in this paper indicate that: 1) the maximum E2E STP increases as the constraint on the expected E2E delay becomes less strict, and such trend is more sensitive to the variation of the number of relays than that of the relay buffer size; 2) on the other hand, the minimum expected E2E delay tends to decrease when a less strict constraint on E2E STP is imposed, and this trend is more sensitive to the variation of the relay buffer size than that of the number of relays.

Traffic accidents involving bicycles are the second most common kind of traffic accident in Japan. In addition, 65.1% of cyclists who had an accident had committed a traffic violation. Although various laws and regulations have been put in place, bicycle-related traffic accidents are hardly decreasing. In this paper, we propose a method for distinguishing bicycle-related traffic violations through behavior detection of cyclists using the Kinect and a photodiode. We detect cyclists using a Kinect and distinguish traffic violations of the bicycle using Skeleton Tracking, distance information, tracking time, the bicycle's travelling location, and illuminance. As experiments, we set up the Kinect and photodiode to capture the front view of a cyclist, and acted out several bicycle traffic violations outdoors. We then evaluated the distinction precision of traffic violation.

Geofencing technology enables various location-based applications by detecting entrance to a predefined region and utilizes the event as a trigger to automatic communication or control of smart devices. In this paper, we implement the proposed geofencing system on Android based smartphone and evalua

A tag system is proposed that offers a practical approach to ubiquitous computing. It provides small and low-power tags that are easy to distribute; does not need a special device to read the tags (in the future), thus enabling their use anytime, anywhere; and has a wide reading range in angle and distance that extends the design space of tag-based applications. The tag consists of a kind of liquid crystal (LC) and a retroreflector, and it sends its ID by switching the LC. A depth sensing camera that emits infrared (IR) is used as the tag reader; we assume that it will be part of the user's everyday devices, such as a smartphone. Experiments were conducted to confirm its potential, and a regular IR camera was also tested for comparison. The results show that the tag system has a wide readable range in terms of both distance (up to 8m) and viewing angle offset. Several applications were also developed to explore the design space. Finally, limitations of the current setup and possible improvements are discussed.

The objective of this research is to realize a method that detects a user's entrance to predefined geographic area so that appropriate services are provided without explicit user action. Though such geofencing technology is gathering attention due to its wide range of applications, it is a challenge to overcome trade-off between power consumption and detection accuracy. Conventional variable interval positioning methods fall short on battery saving due to difficulties such as sparse and erroneous position measurement data, and the unpredictable speed and trajectory of the terminal. In this paper, we propose a method for position detection whose activation frequency is determined by speed toward the target spot. The method is robust against positioning error and fluctuation of the terminal's movement by leveraging the access angle to the target spot. Simulation results show that the proposed access speed correction method reduces power consumption from 42% to 52% against conventional method, while holding the false negative ratio to detect the target spot to less than 5%.

Many people in the modern world feel that they are poor at face-to-face communication.We have developed a topic-providing system that can infer daily life behavior and provides users with their conversation partner’s information, including hometown, hobbies and life log at the advent of face-to-face communication. The life logs are details about a user’s life, and are generated using Bayesian network on the basis of sensor values by our system. This system enables users to access other users’ behavior from the accumulated life logs and utilize this information to generate a topic for conversation.

Reducing the energy consumed in the use of smart phones has become a major challenge for application developers. While this problem can be addressed at various levels, it is important to reduce the energy consumption of individual applications which can vary greatly depending on the behavior of the application. Energy profiling methods are required in order to identify the points in which the applications are consuming excessive energy and to examine how to reduce overall energy consumption by applications.

This paper describes the design and prototype implementation of MIntOS (Mobile Interaction Optimization System), a system for improving mobile interaction in web-based activities. MIntOS monitors users' interactions both for gathering interaction history and for the runtime construction of interaction context. A simple approach based on interaction burstiness is used to break interaction sequences into Trails, which approximates user tasks. Such Trails are used to generate rules for online, context-sensitive prediction of future interaction sequences. Predicted user interaction sequences are then optimized to reduce the amount of user input and user wait time using techniques such as interaction short-cuts, automatic text copying and form-filling, as well as page pre-fetching. Such optimized interaction sequences are, at real-time, recommended to the user through UI enhancements in a non-intrusive manner.

The small form-factor of mobile handsets and the longer, variable latency of cellular networks negatively affect user experience in mobile web related activities. In this paper we describe the design and prototype implementation of a framework for improving mobile web interaction based on monitored interaction history and runtime interaction context. Our framework predicts future interaction sequences and optimizes predicted user interactions with navigation shortcuts and automatic text copying and formfilling

This paper describes an evolution and standardization trends of the wireless channel modeling activities towards IMT-Advanced. In particular, the new developed and standardized ITU-R IMT-Advanced multiple-input-multiple-output (MIMO) Channel Model (IMT-Adv MCM) is detailed. The IMT-Adv MCM is compared with the well-known the 3GPP/3GPP2 Spatial Channel Model (SCM), and their main similarities and differences are pointed out. The performance of MIMO systems is greatly influenced by the spatial-temporal correlation properties of the underlying MIMO channels. Here, we investigate the spatial-temporal correlation characteristics of the 3GPP/3GPP2 SCM and the IMT-Adv MCM in term of their spatial multiplexing and spatial diversity gains. The main goals of this paper are to summarize the current state of the art, as well as to point out the gaps in the wireless channel modeling works, and thus hopefully to stimulate research in these areas.

Web applications routinely handle sensitive data, and many people rely on them to support various daily activities, so errors can have severe and broad-reaching consequences. Unlike most desktop applications, many web applications are written in scripting languages, such as PHP. The dynamic features commonly supported by these languages significantly inhibit static analysis and existing static analysis of these languages can fail to produce meaningful results on realworld web applications.

We propose a secure route optimization mechanism for network mobility management. We also solve three problems to achieve the route optimization: Mobile Router’s security association, need of Correspondent Node’s Mobile IPv6-awareness, and location privacy. In order to solve the problems, we make a Mobile Router a secure proxy of a Mobile Network Node so that the Mobile Router can send a Proxy Binding Update to a Home Agent of the Mobile Network Node in a secure way. We also use Multi-key Cryptographically Generated Addresses (MCGA). By using MCGA, a Mobile Network Node can securely authorize a Mobile Router to use the same address. At the same time, a Home Agent of a Mobile Network Node can also verify that the Binding Update is from either an actual address owner or an authorized proxy. Having performed an analysis of our secure route optimization over rather realistic environment, we show we can save propagation path length between the Home Agent of the Mobile Network Node and the Mobile Router.

In this paper, we compare the downlink capacity and throughput between the variable spreading factor-orthogonal frequency and code division multiple access (VSF-OFCDMA) with one-cell frequency reuse, and the orthogonal frequency division multiple access (OFDMA) with conventional three-cell frequency reuse. Since the multiuser diversity gain in OFDMA systems can be achieved by approximately designing its access schemes, while it is non-trivial for the VSF-OFCDMA systems, the effect of both access schemes on the link capacity are investigated. Our simulation results reveal that although the multiuser diversity gain achieved by OFDMA systems can compensate the loss of low frequency reuse at low to mid range of signal-to-interference-plus-noise ratio (SINR) values, the achievable throughput of VSF-OFCDMA systems is much higher than the OFDMA systems. Furthermore, the impact of user’s location on the inter-cell-interference is also reported.

Linear least squares (LLS) estimation is a low complexity but sub-optimum method for estimating the location of a mobile terminal (MT) from some distance measurements. It requires selecting one of the fixed terminals (FTs) as a reference FT for obtaining a linear set of expressions. However, selection of the reference FT is commonly performed arbitrarily in the literature. In this paper, a method for selection of the reference FT is proposed, which improves the location accuracy compared to a fixed selection of the reference FT. Moreover, a covariance- matrix based LLS estimator is proposed in line of sight (LOS) and non-LOS (NLOS) environments which further improves accuracy since the correlations between the observations are exploited. Simulation results prove the effectiveness of the proposed techniques.

It is notoriously difficult to program a solid web application. Besides addressing web interactions, state maintenance, and whimsical user navigation behaviors, programmers must also avoid a minefield of security vulnerabilities. The problem is twofold. First, we lack a clear understanding of the new computation model underlying web applications. Second, we lack proper abstractions for hiding common and subtle coding details that are orthogonal to the business functionalities of specific web applications.

The purpose of this research is to realize a service discovery protocol that offers denial-of-service (DoS) attack resistance such that even devices with poor CPU resources can be protected from, attacks by more powerful clients. We propose a brand-new method that extends the existing Puzzle Auction, a general-purpose anti-DoS method, by combining it with our original risk-based priority control function. Risk is used as the criteria to evaluate the possibility that a received message is a part of a DoS attack. The server evaluates the risk from the difficulty of the puzzle attached to the client's message and the solution waiting time, which is the time the server has to wait until it receives a solution to the puzzle. CPU resource protection on the server and improved response to the client are achieved at the same time by the proposed priority control method. Experiments that examine six scenarios covering a wide range of situations show that the proposed method offers good performance for a wide range of scope S, which is the parameter used to define the granularity of the risk evaluation. The proposed method shows an improvement in response ratio, from, 18.2% to 51.2%, in the scenario that can not be well handled by the existing puzzle method. Also for the other scenarios, the proposed method approximately matches the performance of the existing puzzle method.

Wireless networks have the feature that the data-rate in a wireless link varies with the signal quality. TCP congestion control cannot handle such data-rate variation in the wireless link and its performance deteriorates. In this paper, we propose a TCP flow control scheme that suits 3G mobile communication systems. The proposed flow control scheme can rapidly respond to data-rate variations by having intermediate nodes provide explicit information about the data-rate in the wireless link. Simulations show that the proposed scheme improves TCP performance substantially in terms of throughput and delay over a wide range of data-rate variation.

The loss of retransmitted segments leads to sub-optimal TCP performance, because these segments, generated by the fast retransmit algorithm and the response of partial ACK under fast recovery, are not well handled in conventional TCP. This paper introduces an algorithm to recover these lost retransmissions for NewReno TCP and details the steps to implement it. It provides careful retransmission by considering the loss of unacknowledged segments. The algorithm is followed by two options for restoring the congestion control state; both reduce the moderate transmission rate which mitigates network congestion, ns2 simulations show that the algorithm can overcome the loss of retransmitted segments. Moreover, it also suppresses the unnecessary throughput degradation more effectively than NewReno TCP. The options for restoring the congestion control state also show adequate performance under retransmitted segment loss

We propose a new environment for testing the behavior of TCP. We analyze existing test methodologies and show that there is still a need to reduce the loads imposed on both the worker and the expert. The Auto Detector is extensible and so well supports both the automation of predefined tasks and the communication tools needed to ensure gradual refinement by the participants. To show the effectiveness of our proposal, actual software flaws found in HP/UX and the Windows operating system are taken as examples of how to realize the automation of reproduction and detection tasks; it is flexible enough to resolve real-world issues.

We address the interaction between TCP and RLC (Radio Link Control), the link layer retransmission protocol in W-CDMA, a 3rd generation cellular wireless network technology, in evaluating TCP performance in following points; l) Supress delay-jitter in link layer to avoid excess retransmissions. 2) Clarify the trade-off between jitter-suppression and link utilization to improve TCP throughput. 3) Optimize the link layer and TCP parameters. We show how to find the TCP and link ARQ parameters that yield optimum overall performance; simulations and emulation confirm their effectiveness. The coexistence of ARQ and TCP can lead to inefficient interaction; the delay-jitter on the link layer may trigger spurious TCP retransmission. The solution is to suppress jitter on the link layer. To manage the trade-off between this suppression and link utilization, we optimized with link parameter.

For mobile information access, client caching is widely used for coping with server unavailability due to temporary disconnection of the network. Cache-miss is the most visible phenomenon to users caused by the disconnection. When multiple clients are isolated from servers, cache-miss happening on a client can be fulfilled using cache contents on other clients. Using a mechanism called disconnected operation, clients of the Coda File System can continue to work without contacting servers; however, clients cannot pass files between them by themselves. This paper presents the design and implementation of two mechanisms: import/export and session server. These mechanisms add read-sharing capability for clean objects to clients disconnected from Coda servers with reasonable response time.