移动智能终端安全即时通信方法

针对移动智能终端即时通信安全问题,提出了一种不可信互联网条件下移动智能终端安全通信方法。该方法设计并实现了一种在服务器和通信信道均不可信情况下的可信密钥协商协议。理论分析表明,所提出的密钥协商协议可以确保通信双方所协商会话密钥的真实性、新鲜性和机密性等诸多安全特性。密钥协商完成之后,基于透明加解密技术即可以确保即时通信双方语音/视频通信信息的机密性和完整性。真实移动互联网环境下的测试也表明该方法是高效和安全的,密钥协商可以在1~2 s完成,攻击者无法获取即时通信的明文信息。     

Gratifications for using CMC technologies: A comparison among SNS,IM, and e-mail

Why and how people choose to use a particular computer-mediated communication (CMC) technology is a major concern. This study seeks to address the issues by applying the uses and gratifications theory, and attempts to explore the general and specific gratifications sought from the use of three CMC technologies. Three separate empirical surveys were conducted to investigate the gratifications sought from social networking sites, instant messaging, and e-mail. Then factor analysis was undertaken to extract the gratifications sought from each CMC technology. The extracted gratifications sought were then compared among the three technologies for concluding the general and specific gratifications. Four general gratifications were extracted among the three CMC technologies, including relationship maintenance, information seeking, amusement, and style. Two gratifications were specific: the sociability gratification sought from using instant messaging and social networking sites; and the gratification of kill time sought from using instant messaging. Moreover, the important levels of gratifications sought from the three CMC technologies were found to be different. Our findings provide evidence to explain why not all traditional CMC technologies are replaced by innovative and advanced ones. The results of this study may be applied to CMC technology design and provide implications for future research.     

Working with tweets vs. working with chats: An experiment on collaborative problem solving

This papers aims to explore how “working with tweets” differs from “working with chats”. With eight experimental sessions involving 120 Italian students, we investigate how the well known 140-characters limit and other subtle differences between Twitter and a typical instant messenger affect group problem solving performances. In our laboratory experiment, teams of the same size carry out a problem solving task communicating via Twitter or Skype instant messaging. Comparative group performance is measured in terms of successful task completion time. Our results show that the lower number and volume of text messages exchanged via Twitter does not negatively affect group performance: Twitter teams are just as effective as Skype instant messaging teams. These results can be interpreted in accordance with the latest developments in multiple media choice and virtual team effectiveness theories, disclosing interesting windows of opportunities for “working with tweets” in the forthcoming organizational settings.     

RU mad @ me? Social anxiety and interpretation of ambiguous text messages

Increasingly, young adults' social interactions are taking place via computer-mediated communication (CMC). Recent research suggests that socially anxious youth, in particular, may prefer interacting via CMC and show less inhibition and greater self-disclosure in such contexts. However, cognitive features of social anxiety, such as interpretation bias, have not been studied in this context. The goal of this research was to examine the phenomenon of interpretation bias (tendency to ascribe threatening interpretations to ambiguous social situations) in response to text messages. In Study 1, a new vignette measure of interpretation bias in the context of text messaging (IB-CMC) was developed and piloted with a sample of N = 215 undergraduates. This new measure displayed good psychometric properties and evidence of construct validity. For example, negative interpretation bias in CMC was associated with two established measures of interpretation bias in face-to-face situations and symptoms of social anxiety. In Study 2, the effects of sender characteristics (specifically, gender of sender) were examined in a sample of N = 353 undergraduates. Overall, participants interpreted ambiguous text messages from female senders as more negative and less benign than messages from male senders, and this effect was particularly pronounced among male participants.     

On the Performance of Permutation Codes for Multi-User Communication

Permutation coding for multi-user communication schemes that originate from the Fast Frequency Hopping/Multiple Frequency Shift Keying modulation is investigated. Each sender is either passive or sends some signal formed as the concatenation of M elementary signals having M different specified frequencies. There is also a jammer, who can introduce disturbances. A single disturbance is either sending the signal that contains all M frequencies at a certain time instant or sending some elementary signal at all time instants. Each receiver receives a vector of M sets, where a set at each time instant contains a fixed frequency if and only if the corresponding elementary signal was sent by either some sender or the jammer. The task of the receiver is to uniquely decode the message of his sender. We present regular constructions of permutation codes for this scheme given the following parameters: the number of frequencies, number of pairs (sender, receiver), number of messages per sender, and maximum number of disturbances of the jammer.     

A Three-Layer Secure Architecture for IP Multimedia Subsystem-Based Instant Messaging

ABSTRACT

A packet-based network to provide telecommunication services independent from the underlying access and transport technologies is known as a next generation network. An IP multimedia subsystem (IMS) provides an architectural framework for the next generation networks and includes variety of services such as presence, instant messaging, push-to-talk over cellular, multiparty conference, and so forth. IMS-based instant messaging is available in two flavors (immediate messaging and session-based messaging). Both flavors are subject to different types of security threats. An attacker can generate an immediate messaging flood by sending enormous number of messages to deny the services to a group of users or to an individual. Session-based messaging is facing threats such as invite flooding attack, session modification attack, and session teardown attack. In this paper, we developed a security mechanism, consisting of three layers, to secure the messaging service from flooding attacks and session-based attacks and the like. The simulation results show a good improvement in the existing security mechanism of the IMS-based instant messaging service.     

Perceived academic effects of instant messaging use

College students use information and communication technologies at much higher levels and in different ways than prior generations. They are also more likely to multitask while using information and communication technologies. However, few studies have examined the impacts of multitasking on educational outcomes among students. This study fills a gap in this area by utilizing a large-sample web-based survey of college student technology usage to examine how instant messaging and multitasking affect perceived educational outcomes. Since multitasking can impede the learning process through a form of information overload, we explore possible predictors of academic impairment due to multitasking. Results of this study suggest that college students use instant messaging at high levels, they multitask while using instant messaging, and over half report that instant messaging has had a detrimental effect on their schoolwork. Higher levels of instant messaging and specific types of multitasking activities are associated with students reporting not getting schoolwork done due to instant messaging. We discuss implications of these findings for researchers studying the social impacts of technology and those in higher education administration.     

Towards an open protocol for secure online presence notification

It is important to know the presence of other concurrently online users before real-time communication can be established with them. While many instant messaging (IM) systems are available, there is no standard protocol for online presence notification due to the proprietary nature of such systems. These systems generally have many security weaknesses such as anonymous messaging, message spoofing, account hijacking and authorization overriding because they depend heavily on client-side operations. This paper proposes an open protocol for online presence notification that also provides negotiation support for real-time communication services. The open nature of the protocol promotes interoperability, but demands higher levels of security than proprietary ones. The separation of instant messaging from online presence notification also distinguishes this open protocol from others. Furthermore, a relatively secure presence notification system based on the proposed protocol has been implemented with its performance evaluated.     

Computer mediated communication for social and academic purposes: Profiles of use and University students’ gratifications

The present study approaches the Internet as a social space, where university students make use of computer mediated communication (CMC) applications, i.e. e-mail, instant messaging and social network sites, in order to satisfy social and academic needs. We focus on university students, because they represent one of the most avid groups of CMC users and additionally, because they are expected to carry their perceptions of media with them into the work place and their social life. In order to investigate this issue, we conducted an empirical research using, as a target group, a sample of students from a specific Greek University. Grounded in the “uses and gratifications” perspective, we investigated the various profiles of CMC use by students along with (a) the students’ perceptions about social and academic usefulness of CMC applications, (b) the extent up to which these perceptions are correlated with students’ prior experience with the use of CMC applications, and (c) how both of these factors can predict the frequency of present use of CMC for social or academic purposes respectively. The results reveal that although these three CMC applications constitute “functional alternatives” (media that satisfy similar needs) they are different to the degree of their “functionality” for the gratification of social and academic needs. Furthermore, the degree of CMC use by students is not correlated with the years of CMC experience, but with the profile of use that students dynamically adopt according to their daily needs and preferences. The results provide evidence for the current CMC use by university students and can be useful for the implementation of further academic policies regarding CMC use in Higher Education settings.     

基于JXTA的P2P即时通信系统设计

课题研究使用JXTA搭建P2P网络,完成即时通信系统。即时通信系统分为发送、中继转发和接收三部分。其中中继转发部分在启动时加入P2P网络,并且在P2P网络中发布提供即时通信服务的通告。发送部分加入P2P网络,通过查找P2P网络通告寻找提供服务的即时通信结点,选择结点形成P2P网络通道。发送端在这个通道基础上建立与接收端的SOCKET连接,将信息传递到接收端。     

基于身份的多接收者(多消息)匿名混合签密机制

为满足广播环境下通信数据的机密性和认证性需求以及消息收发双方的匿名性,本文提出基于身份的多接收者匿名混合签密机制,满足收发双方的匿名性保护需求,并且接收者具有解密独立性;正确性分析及安全性证明表明本文机制是安全、有效的多接收者匿名混合签密机制;相较与现有方案而言,除具有保密性和不可伪造性之外,本文机制具有更优的性能,如更高的匿名性、公开验证性等.同时,将本文机制改进后,提出具有收发双方匿名性、公开验证性、不可否认性等安全属性的多接收者多消息混合签密机制,实现广播通信环境下用户的多消息发送需求.     

“What do they snapchat about?” Patterns of use in time-limited instant messaging service

The use of Snapchat – a time-limited instant messaging service – has been rapidly rising amongst adolescents. However, the exact nature of Snapchat use remains difficult to examine due to the self-destructive nature of content sent and received via this service. We report an online survey conducted with the use of a memory sampling method to enquire about the specific details of the very last image or video each participant sent and received via Snapchat. We found that users mainly share ‘selfies’, typically embed text and ‘doodles’ with photos they share, use it mostly at home, and primarily for communication with close friends and family as an ‘easier and funnier’ alternative to other instant messaging services. We also found that high intensity of Snapchat use was more associated with bonding rather than bridging social capital. We discuss those findings in the context of existing studies on the use of instant messaging services and social networking sites.     

Exploring the impact of instant messaging on subjective task complexity and user satisfaction

Instant messaging (IM) technologies are being rapidly deployed in the workplace. Current studies largely focus on the adoption of IM and how IM is used. Little research has been conducted to understand the potential impact of using IM in the workplace. This paper theorizes and empirically tests how the frequency of IM interruptions and the position power of message sender could interact with an individual’s polychronic orientation, that is, multitasking preference, and jointly influence employee satisfaction and subjective task complexity. The present study illustrates that polychronic knowledge workers are more satisfied with the multitasking work process deploying IM technology than monochronic ones. In addition, the effect of interruptions is dependent upon an individual’s polychronic orientation. The increase in interruption frequency only reduces the process satisfaction of monochronic individuals but not polychronic individuals. Further, the polychronic orientation of message receivers also influences how they process information. When IM messages are sent from their supervisors, monochronic individuals tend to prioritize tasks and perceive a lower level of overall task complexity. The information processing of polychronic individuals seem to be less influenced by the position power of message sender.     

Beyond Bandwidth: Dimensions of Connection in Interpersonal Communication

Computer-mediated communication (CMC) is a keystone of computer-supported collaborative work. Current CMC theory utilizes an information channel metaphor in which media vary according to how well they afford the transfer of messages in the channel, i.e., bandwidth. This paper draws attention to a different aspect of communication argued to be equally important: a relation between people that defines a state of communicative readiness in which fruitful communication is likely. Drawing on research on instant messaging (Nardi et al., 2000) and face to face communication (Nardi et al., 2002; Nardi and Whittaker, 2003), as well as related literature, three dimensions of connection that activate readiness are proposed: affinity, commitment, and attention. These dimensions comprise a field of connection between dyads. A field of connection is conceptualized as a labile, multidimensional space in which the values of the dimensions vary according to the history of communicative activity. Affinity, commitment, and attention are constantly monitored, negotiated, and managed through social bonding, expression of commitment, and capture of attention. The management of fields of connection requires significant interactional work to sustain communication over time.     

Understanding User Satisfaction With Instant Messaging: An Empirical Survey Study

The current article examines user satisfaction with instant messaging in building and maintaining social relationships with friends, family members, and others. The research model integrates motivation theory with media capacity theories to explain how the attributes of media capacity (e.g., social presence and media richness) and users' intrinsic and extrinsic motivations toward using instant messaging influence user satisfaction. Data were collected from a sample of 247 Chinese university students via an online survey. The results suggest that perceived enjoyment, perceived social presence, and perceived usefulness are key to user satisfaction. Perceived social presence and perceived media richness are positively associated with perceived enjoyment. It was also found that perceived enjoyment, perceived social presence, and perceived media richness have significant effects on perceived usefulness. Of interest, perceived enjoyment and perceived social presence have stronger effects on user satisfaction than perceived usefulness.     

Constant companions: Instant messaging conversations as sustainable supportive study structures amongst undergraduate peers

Universities are facing severe cuts in funding and a transformation of both the economic model underpinning higher education and the relationship between students, tutors and universities and the traditional forms of support for students’ learning may be eroded. At the same time, mobile communications, instant messaging and social networking are now widespread amongst students and offer possible opportunities for developing new models of support. This paper reports on the use of instant messaging amongst peers, as part of a study of digitally-mediated communication and collaborative activities, crossing formal and informal boundaries, amongst campus-based undergraduate students, at a large university in the UK. It is argued that instant messaging conversations offers a means of sustainable peer support for students by demonstrating how they emerge from everyday practices, drawing on existing relationships and shared histories and redrawing the boundaries between formal and informal settings and practices. The importance of time is highlighted, showing how longitudinal, dialogic conversations were important for both practical and empathetic support. The potential of the instant messaging conversations in supporting the co-creation of artefacts, meaning making, motivation and affective support are also demonstrated, drawing on detailed examples of authentic conversations. However, such peer support practices remain largely invisible and therefore need acknowledging, fostering and encouraging, working alongside students to understand and develop these ideas so that peer support in universities can build on the existing practices of students themselves.     

Exception handling for copyless messaging

Copyless messaging is a communication paradigm in which only pointers to messages are exchanged between sender and receiver processes. Because of its intrinsically low overhead, copyless messaging is suitable for the efficient implementation of communication-intensive software systems where processes have access to a shared address space. Unfortunately, the very nature of the paradigm fosters the proliferation of programming errors due to the explicit use of pointers and to the sharing of data. In this paper we study a type discipline for copyless messaging that, together with some minimal support from the runtime system, is able to guarantee the absence of communication errors, memory faults, and memory leaks in the presence of exceptions. To formalize the semantics of processes we draw inspiration from software transactional memories: in our case a transaction is a process that is meant to accomplish some exchange of messages and that should either be executed completely, or should have no observable effect if aborted by an exception.     

一种XMPP即时消息系统的动态模型的实现

针对用户在利用现有即时消息系统的在线感知模块所提供的感知信息寻找正确交互对象时碰到的问题,通过分析现有的基于XMPP即时消息系统结构和在线感知实现的基本方法,结合在现有XMPP客户端中加入收集用户事件信息组件进行数据的收集,并利用决策树的分类算法对收集数据进行处理,从而实现一种可以预测的用户回应可能性的动态在线感知模型,最后利用仿真实验的方式,对模型进行了仿真分析和验证,从而得出在XMPP协议的即时消息系统中实现这种可预测用户回应的动态的在线感知模型的是可行的(其准确率约为90%),与现有其他在线感知功能模块相比,运用该方法实现的模型由于引入了预测用户行为的动态感知,因此用户在利用该模型寻找正确交互对象时的效率更高,并被用于国家网络科技环境建设的多个项目中,收到了良好效果.     

Streaming XML with Jabber/XMPP

Jabber is an open alternative to closed instant messaging (IM) and presence services. At its core is the extensible messaging and presence protocol (XMPP), which defines how to stream XML content and is being used to build not only a large open IM network but also a wide range of XML applications. This article provides an overview of Jabber/XMPP protocols and technologies, as well as an introduction to XMPP-based applications.     

The computational power of population protocols

We consider the model of population protocols introduced by Angluin et al. (Computation in networks of passively mobile finite-state sensors, pp. 290–299. ACM, New York, 2004), in which anonymous finite-state agents stably compute a predicate of the multiset of their inputs via two-way interactions in the family of all-pairs communication networks. We prove that all predicates stably computable in this model (and certain generalizations of it) are semilinear, answering a central open question about the power of the model. Removing the assumption of two-way interaction, we also consider several variants of the model in which agents communicate by anonymous message-passing where the recipient of each message is chosen by an adversary and the sender is not identified to the recipient. These one-way models are distinguished by whether messages are delivered immediately or after a delay, whether a sender can record that it has sent a message, and whether a recipient can queue incoming messages, refusing to accept new messages until it has had a chance to send out messages of its own. We characterize the classes of predicates stably computable in each of these one-way models using natural subclasses of the semilinear predicates. James Aspnes was supported in part by NSF grants CNS-0305258 and CNS-0435201. David Eisenstat was supported in part by a National Defense Science and Engineering Graduate Fellowship and by a Gordon Y. S. Wu Graduate Fellowship. Eric Ruppert was supported in part by the Natural Sciences and Engineering Research Council of Canada.