Complexity of increasing the secure connectivity in wireless ad hoc networks

We consider the problem of maximizing the secure connectivity in wireless ad hoc networks, and analyze complexity of the post-deployment key establishment process constrained by physical layer properties such as connectivity, energy consumption and interference. Two approaches, based on graph augmentation problems with nonlinear edge costs, are formulated. The first one is based on establishing a secret key using only the links that are already secured by shared keys. This problem is in NP-hard and does not accept polynomial time approximation scheme PTAS since minimum cutsets to be augmented do not admit constant costs. The second one extends the first problem by increasing the power level between a pair of nodes that has a secret key to enable them physically connect. This problem can be formulated as the optimal key establishment problem with interference constraints with bi-objectives: (i) maximizing the concurrent key establishment flow, (ii) minimizing the cost. We prove that both problems are NP-hard and MAX-SNP with a reduction to MAX3SAT problem.

I-vector based speaker recognition using advanced channel compensation techniques

This paper investigates advanced channel compensation techniques for the purpose of improving i-vector speaker verification performance in the presence of high intersession variability using the NIST 2008 and 2010 SRE corpora. The performance of four channel compensation techniques: (a) weighted maximum margin criterion (WMMC), (b) source-normalized WMMC (SN-WMMC), (c) weighted linear discriminant analysis (WLDA), and; (d) source-normalized WLDA (SN-WLDA) have been investigated. We show that, by extracting the discriminatory information between pairs of speakers as well as capturing the source variation information in the development i-vector space, the SN-WLDA based cosine similarity scoring (CSS) i-vector system is shown to provide over 20% improvement in EER for NIST 2008 interview and microphone verification and over 10% improvement in EER for NIST 2008 telephone verification, when compared to SN-LDA based CSS i-vector system. Further, score-level fusion techniques are analyzed to combine the best channel compensation approaches, to provide over 8% improvement in DCF over the best single approach, (SN-WLDA), for NIST 2008 interview/ telephone enrolment-verification condition. Finally, we demonstrate that the improvements found in the context of CSS also generalize to state-of-the-art GPLDA with up to 14% relative improvement in EER for NIST SRE 2010 interview and microphone verification and over 7% relative improvement in EER for NIST SRE 2010 telephone verification.

Engaging students in authoring and playing computer games

Computer games have become a commonplace but engaging activity among students. They enjoy playing computer games as they can perform larger-than-life activities virtually such as jumping from great heights, flying planes, and racing cars; actions that are otherwise not possible in real life. Computer games also offer user interactivity which gives them a certain appeal. Considering this appeal, educators should consider integrating computer games into student learning and to encourage students to author computer games of their own. It is thought that students can be engaged in learning by authoring and using computer games and can also gain essential skills such as collaboration, teamwork, problem solving and deductive reasoning. The research in this study revolves around building student engagement through the task of authoring computer games. The study aims to demonstrate how the creation and sharing of student-authored educational games might facilitate student engagement and how ICT (information and communication technology) plays a supportive role in student learning. Results from this study may lead to the broader integration of computer games into student learning and contribute to similar studies. In this qualitative case study, based in a state school in a low socio-economic area west of Brisbane, Australia, students were selected in both junior and senior secondary classes who have authored computer games as a part of their ICT learning. Senior secondary students (Year 12 ICT) were given the task of programming the games, which were to be based on Mathematics learning topics while the junior secondary students (Year 8 ICT) were given the task of creating multimedia elements for the games. A Mathematics teacher volunteered to assist in the project and provided guidance on the inclusion of suitable Mathematics curricular content into these computer games. The student-authored computer games were then used to support another group of Year 8 Mathematics students to learn the topics of Area, Volume and Time. Data was collected through interviews, classroom observations and artefacts. The teacher researcher, acting in the role of ICT teacher, coordinated with the students and the Mathematics teacher to conduct this study. Instrumental case study was applied as research methodology and Third Generation Activity Theory served as theoretical framework for this study. Data was analysed adopting qualitative coding procedures. Findings of this study indicate that having students author and play computer games promoted student engagement and that ICT played a supportive role in learning and allowed students to gain certain essential skills. Although this study will suggest integrating computer games to support classroom learning, it cannot be presumed that computer games are an immediate solution for promoting student engagement.

An interpretative phenomenological analysis of participation in a pro-anorexia Internet site and its relationship to disordered eating

Pro-anorexia Internet sites aim to promote, support and discuss anorexia nervosa. Media coverage has raised concerns that sites may increase the level of eating disorders. This research examines the meaning of participation in a pro-anorexia Internet site and its relationship with disordered eating by using an interpretative phenomenological analysis of fifteen separate message ‘threads’ followed over a six-week period. Four themes were identified: (1) tips and techniques; (2) ‘ana’ v. anorexia nervosa; (3) social support; and (4) need for anorexia. Findings suggest participation was multi-purpose, providing a coping function in relation to weight loss, and the contribution of sites to increased levels of eating disorders is not inevitable.

Computer experiment – a case study for modelling and simulation of manufacturing systems

Deterministic computer simulation of physical experiments is now a common technique in science and engineering. Often, physical experiments are too time consuming, expensive or impossible to conduct. Complex computer models or codes, rather than physical experiments lead to the study of computer experiments, which are used to investigate many scientific phenomena. A computer experiment consists of a number of runs of the computer code with different input choices. The Design and Analysis of Computer Experiments is a rapidly growing technique in statistical experimental design. This paper aims to discuss some practical issues when designing a computer simulation and/or experiments for manufacturing systems. A case study approach is reviewed and presented.

The role for police in addressing alcohol-related harm inside and outside licensed premises

Alcohol consumption is enmeshed with Australian culture (Palk, 2008) and the use and misuse of alcohol contributes to considerable health and social harms (Barbor et al., 2010; English et al., 1995; Gutjahr, Gmel, & Rehm, 2001; Palk, 2008; Steenkamp, Harrison, & Allsop, 2002). Despite shifts in the way that alcohol is consumed and how it is used, it has been reported that one-third of all alcohol consumed is done so within licensed premises (Lang, Stockwell, Rydon, & Gamble, 1992). Consequently, licensed premises are over-represented as settings in which alcohol-related harms occur. These harms, particularly those related to violence, are associated with particular licensed premises operating in the night-time economy (Briscoe & Donnelly, 2001b; Chikritzhs, Stockwell, & Masters, 1997; Homel, Tomsen, & Thommeny, 1991; Stockwell, 1997). Police have a role in not only responding to the manifestation of harms, such as crime, injuries, assaults, domestic violence, stealing and sexual offences, but they also have a role in preventing problems, and thereby reducing alcohol and other drug-related harms (Doherty & Roche, 2003). Given the extent of alcohol consumption within licensed premises and the nature and extent of the harms, as well as the lack of opportunity to influence outcomes in other settings (e.g. the home), licensed premises offer police and other stakeholders a significant opportunity to influence positively the reduction of alcoholrelated harm. This research focuses specifically on the police role in policing licensed premises. Primarily, this research aims to investigate the factors which are relevant to why and how police officers respond to alcohol-related incidents inside and outside licensed premises. It examines the attitudes and beliefs of police and assesses their knowledge, capacity and ability to effectively police licensed premises. The research methodology uses three distinct surveys. Each contributes to understanding the motivations and practice of police officers in this important area of harm reduction. Study One involved a survey of police officers within a police district (Brisbane Central District) in Queensland, Australia and used a comprehensive questionnaire involving both quantitative and qualitative techniques. A key research outcome of Study One was the finding that officers had low levels of knowledge of the strategies that are effective in addressing alcohol-related harm both inside and outside licensed premises. Paradoxically, these officers also reported extensive recent experience in dealing with alcohol issues in these locations. In addition, these officers reported that alcohol was a significant contextual factor in the majority of matters to which they responded. Officers surveyed reported that alcohol increased the difficulty of responding to situations and that licensed premises (e.g. nightclubs, licensed clubs and hotels) were the most difficult contexts to police. Those surveyed were asked to self-assess their knowledge of the Liquor Act (Qld), which is the primary legislative authority in Queensland for regulating licensed premises. Surprisingly, well over half of the officers (65%) reported ‘no’ to ‘fair’ knowledge of the Act, despite officers believing that their skill level to police such premises was in the ‘good to very good range’. In an important finding, officers reported greater skill level to police outside licensed premises than inside such premises, indicating that officers felt less capable, from a skill perspective, to operate within the confines of a licensed premise than in the environment immediately outside such premises. Another key finding was that officers reported greater levels of training in responding to situations outside and around licensed premises than to situations inside licensed premises. Officers were also asked to identify the frequency with which they employed specified regulatory enforcement and community-based strategies. Irrespective of the type of response, ‘taking no action’ or passive policing interventions were not favoured by officers. The findings identified that officers favoured taking a range of strategies (sending home, releasing into the custody of friends, etc.) in preference to arrest. In another key finding, officers generally reported their support for operational stakeholder partnership approaches to policing licensed premises. This was evidenced by the high number of officers (over 90%) reporting that there should be shared responsibility for enforcing the provisions of the Liquor Act. Importantly, those surveyed also identified the factors which constrain or prevent them from policing licensed premises. Study Two involved interviewing a small but comprehensive group (n=11) of senior managers from within the Queensland Police Service (QPS) who have responsibility for setting operational and strategic policy. The aim of this study was to examine the attitudes, perceptions and influence that senior officers (at the strategy and policy-setting level) had on the officers at the operational level. This qualitative study was carried out using a purposive sampling (Denzin & Lincoln, 2005; Guba & Lincoln, 1989), focused interview and thematic analytic approach. The interview participants were drawn from three tiers of management at district, regional as well as the whole-of-organisational level. The first key theme emerging from the study related to role, in terms of both the QPS broader organisational role, and the individual officer role with respect to the policing of licensed premises. For the QPS organisational role, participants at all three strategic levels had a high degree of congruity as to the organisations service role; that is, to enhance public safety. With respect to participants’ beliefs as to whether police officers have knowledge and understanding of their individual roles concerning licensed premises (as opposed to the QPS role), participants reported most commonly that officers had a reasonable to clear understanding of their role. Participant comments also were supportive of the view that officers operating in the research area, Brisbane Central District (BCD), had a clearer understanding of their role than police operating in other locations. The second key theme to emerge identified a disparity between the knowledge and capability of specialist police, compared with general duties police, to police licensed premises. In fact, a number of the responses to a variety of questions differentiated specialist and general police in a range of domains. One such example related to the clarity of understanding of officer role. Participants agreed that specialist police (Liquor Enforcement & Proactive Strategies [LEAPS] officers) had more clarity of understanding in terms of their role than generalist police. Participants also were strongly of the opinion that specialist police had higher skill levels to deal with issues both inside and outside licensed premises. Some participants expressed the view that general duty police undertook purely response-related activities, or alternatively, dealt with lower order matters. Conversely, it was viewed that specialist police undertook more complex tasks because of their higher levels of knowledge and skill. The third key theme to emerge concerned the identification of barriers that serve to restrict or prevent police officers from policing licensed premises. Participant responses strongly indicated that there was a diversity of resourcing barriers that restrict police from undertaking their roles in licensed premises. Examples of such barriers were the lack of police and the low ratio of police to patrons, available officer time, and lack of organisational investment in skills and knowledge acquisition. However, some participants indicated that police resourcing in the BCD was appropriate and officers were equipped with sufficient powers (policy and legislation). Again, the issue of specialist police was raised by one participant who argued that increasing the numbers of specialist police would ameliorate the difficulties for police officers policing licensed premises. The fourth and last key theme to emerge from Study Two related to the perception of senior officers regarding the opportunity and capability of officers to leverage off external partnerships to reduce harms inside and outside licensed premises. Police working in partnership in BCD was seen as an effective harm reduction strategy and strongly supported by the participants. All participants demonstrated a high degree of knowledge as to who these partners were and could identify those government, non-government and community groups precisely. Furthermore, the majority of participants also held strong views that the partnerships were reasonably effective and worked to varying degrees depending on the nature of the partnership and issues such as resourcing. These senior officers identified better communication and coordination as factors that could potentially strengthen these partnerships. This research finding is particularly important for senior officers who have the capacity to shape the policy and strategic direction of the police service, not only in Queensland but throughout Australasia. Study Three examined the perceptions of those with links to the broader liquor industry (government, non-government and community but exclusive of police) concerning their understanding of the police role and the capacity of police to reduce alcohol-related harm inside and outside licensed premises, and their attitudes towards police. Participants (n=26) surveyed represented a range of areas including the liquor industry, business represenatives and government representatives from Queensland Fire and Rescue Service, Queensland Ambulance Service, Brisbane City Council and Queensland Health. The first key theme to emerge from Study Three related to participant understanding of the QPS organisational role, and importantly, individual officer role in policing licensed premises. In terms of participant understanding of the QPS role there was a clear understanding by the majority of participants that the police role was to act in ways consistent with the law and to otherwise engage in a range of enforcement-related activities. Participants saw such activities falling into two categories. The first category related to reactive policing, which included actions around responding to trouble in licensed premises, monitoring crowd controllers and removing trouble-makers. In the second category, proactive approaches, participants identified the following activities as consistent with that approach: early intervention with offenders, support of licensed premises operators and high visibility policing. When participants were asked about their understanding of individual officer roles in the policing of licensed premises, a range of responses were received but the consistent message that emerged was that there is a different role to be played by general duty (uniformed) police compared to specialist (LEAPS Unit) police, which reflects differences in knowledge, skill and capability. The second key theme that emerged from the data related to the external participants’ views of the knowledge and capability of specialist police, compared with general duty police, to police licensed premises. As noted in the first key theme, participants were universally of the view that the knowledge, skill and capability of police in specialist units (LEAPS Unit) was at a higher level than that of general duty police. Participants observed that these specialist officers were better trained than their colleagues in generalist areas and were therefore better able to intervene knowledgeably and authoritatively to deal with problems and issues as they emerged. Participants also reported that officers working within BCD generally had a positive attitude to their duties and had important local knowledge that they could use in the resolution of alcohol-related issues. Participants also commented on the importance of sound and effective QPS leadership, as well as the quality of the leadership in BCD. On both these measures, there was general consensus from participants, who reported positively on the importance and effectiveness of such leadership in BCD. The third key theme to emerge from Study Three concerned the identification of barriers that serve to restrict or prevent police officers from policing licensed premises. Overwhelmingly, external participants reported the lack of human resources (i.e. police officers) as the key barrier. Other resourcing limitations, such as available officer time, police computer systems, and the time taken to charge offenders, were identified as barriers. Some participants identified barriers in the liquor industry such as ‘dodgy operators’ and negative media attention as limitations. Other constraints to emerge related to government and policy barriers. These were reflected in comments about the collection by government of fees from licensees and better ‘powers’ for police to deal with offenders. The fourth and final key theme that emerged from Study Three related to the opportunities for and capability of police to leverage off external partnerships to reduce harms inside and outside licensed premises. Not surprisingly, participants had a comprehensive knowledge of a broad range of stakeholders, from a diversity of contexts, influential in addressing issues in licensed premises. Many participants reported their relationships with the police and other stakeholders as effective, productive and consistent with the objectives of partnering to reduce alcohol-related harm. On the other hand, there were those who were concerned with their relationship with other stakeholders, particularly those with a compliance function (e.g. Office of Liquor & Gaming Regulation [OLGR]). The resourcing limitations of partners and stakeholders were also raised as an important constraining factor in fulfilling the optimum relationship. Again, political issues were mentioned in terms of the impact on partnerships, with participants stating that there is at times political interference and that politicians complicate the relationships of stakeholders. There are some significant strengths with respect to the methodology of this research. The research is distinguished from previous work in that it examines these critical issues from three distinct perspectives (i.e. police officer, senior manager and external stakeholder). Other strengths relate to the strong theoretical framework that guides and informs the research. There are also some identified limitations, including the subjective nature of self-report data as well as the potential for bias by the author, which was controlled for using a range of initiatives. A further limitation concerns the potential for transferability and generalisability of the findings to other locations given the distinctive nature of the BCD. These limitations and issues of transferability are dealt with at length in the thesis. Despite a growing body of literature about contextual harms associated with alcohol, and specific research concerning police intervention in such contextual harms, there is still much to learn. While research on the subject of police engaging in alcohol-related incidents has focused on police behaviours and strategies in response to such issues, there is a paucity of research that focuses on the knowledge and understanding of officers engaged in such behaviours and practices. Given the scarcity of research dealing with the knowledge, skills and attitudes of police officers responding to harms inside and outside licensed premises, this research contributes significantly to what is a recent and growing body of research and literature in the field. The research makes a practical contribution to police agencies’ understanding of officer knowledge and police practice in ways that have the potential to shape education and training agendas, policy approaches around generalist versus specialist policing, strategic and operational strategy, as well as partnership engagements. The research also makes a theoretical contribution given that the research design is informed by the Three Circle

Crisis response planning in tunnel and road networks

Critical road infrastructure (such as tunnels and overpasses) is of major significance to society and constitutes major components of interdependent, ‘systems and networks’. Failure in critical components of these wide area infrastructure systems can often result in cascading disturbances with secondary and tertiary impacts - some of which may become initiating sources of failure in their own right, triggering further systems failures across wider networks. Perrow1) considered the impact of our increasing use of technology in high-risk fields, analysing the implications on everyday life and argued that designers of these types of infrastructure systems cannot predict every possible failure scenario nor create perfect contingency plans for operators. Challenges exist for transport system operators in the conceptualisation and implementation of response and subsequent recovery planning for significant events. Disturbances can vary from reduced traffic flow causing traffic congestion throughout the local road network(s) and subsequent possible loss of income to businesses and industry to a major incident causing loss of life or complete loss of an asset. Many organisations and institutions, despite increasing recognition of the effects of crisis events, are not adequately prepared to manage crises2). It is argued that operators of land transport infrastructure are in a similar category of readiness given the recent instances of failures in road tunnels. These unexpected infrastructure failures, and their ultimately identified causes, suggest there is significant room for improvement. As a result, risk profiles for road transport systems are often complex due to the human behaviours and the inter-mix of technical and organisational components and the managerial coverage needed for the socio-technical components and the physical infrastructure. In this sense, the span of managerial oversight may require new approaches to asset management that combines the notion of risk and continuity management. This paper examines challenges in the planning of response and recovery practices of owner/operators of transport systems (above and below ground) in Australia covering: • Ageing or established infrastructure; and • New-build infrastructure. With reference to relevant international contexts this paper seeks to suggest options for enhancing the planning and practice for crisis response in these transport networks and as a result support the resilience of Critical Infrastructure.

A social matching system : using implicit and explicit information for personalized recommendation in online dating service

Online dating websites enable a specific form of social networking and their efficiency can be increased by supporting proactive recommendations based on participants' preferences with the use of data mining. This research develops two-way recommendation methods for people-to-people recommendation for large online social networks such as online dating networks. This research discovers the characteristics of the online dating networks and utilises these characteristics in developing efficient people-to-people recommendation methods. Methods developed support improved recommendation accuracy, can handle data sparsity that often comes with large data sets and are scalable for handling online networks with a large number of users.

Development of a Remote Sensing Core Curriculum submitted for the sessions on educational initiatives in Geoscience and Remote Sensing

A Remote Sensing Core Curriculum (RSCC) development project is currently underway. This project is being conducted under the auspices of the National Center for Geographic Information and Analysis (NCGIA). RSCC is an outgrowth of the NCGIA GIS Core Curriculum project. It grew out of discussions begun at NCGIA, Initiative 12 (I-12): 'Integration of Remote Sensing and Geographic Information Systems'. This curriculum development project focuses on providing professors, teachers and instructors in undergraduate and graduate institutions with course materials from experts in specific subject matter for areas use in the class room.

Crypto Topics and Applications I

In this chapter, we discuss four related areas of cryptology, namely, authentication, hashing, message authentication codes (MACs), and digital signatures. These topics represent active and growing research topics in cryptology. Space limitations allow us to concentrate only on the essential aspects of each topic. The bibliography is intended to supplement our survey. We have selected those items which providean overview of the current state of knowledge in the above areas. Authentication deals with the problem of providing assurance to a receiver that a communicated message originates from a particular transmitter, and that the received message has the same content as the transmitted message. A typical authentication scenario occurs in computer networks, where the identity of two communicating entities is established by means of authentication. Hashing is concerned with the problem of providing a relatively short digest–fingerprint of a much longer message or electronic document. A hashing function must satisfy (at least) the critical requirement that the fingerprints of two distinct messages are distinct. Hashing functions have numerous applications in cryptology. They are often used as primitives to construct other cryptographic functions. MACs are symmetric key primitives that provide message integrity against active spoofing by appending a cryptographic checksum to a message that is verifiable only by the intended recipient of the message. Message authentication is one of the most important ways of ensuring the integrity of information that is transferred by electronic means. Digital signatures provide electronic equivalents of handwritten signatures. They preserve the essential features of handwritten signatures and can be used to sign electronic documents. Digital signatures can potentially be used in legal contexts.

Crypto topics and applications II

In this chapter we continue the exposition of crypto topics that was begun in the previous chapter. This chapter covers secret sharing, threshold cryptography, signature schemes, and finally quantum key distribution and quantum cryptography. As in the previous chapter, we have focused only on the essentials of each topic. We have selected in the bibliography a list of representative items, which can be consulted for further details. First we give a synopsis of the topics that are discussed in this chapter. Secret sharing is concerned with the problem of how to distribute a secret among a group of participating individuals, or entities, so that only predesignated collections of individuals are able to recreate the secret by collectively combining the parts of the secret that were allocated to them. There are numerous applications of secret-sharing schemes in practice. One example of secret sharing occurs in banking. For instance, the combination to a vault may be distributed in such a way that only specified collections of employees can open the vault by pooling their portions of the combination. In this way the authority to initiate an action, e.g., the opening of a bank vault, is divided for the purposes of providing security and for added functionality, such as auditing, if required. Threshold cryptography is a relatively recently studied area of cryptography. It deals with situations where the authority to initiate or perform cryptographic operations is distributed among a group of individuals. Many of the standard operations of single-user cryptography have counterparts in threshold cryptography. Signature schemes deal with the problem of generating and verifying electronic) signatures for documents.Asubclass of signature schemes is concerned with the shared-generation and the sharedverification of signatures, where a collaborating group of individuals are required to perform these actions. A new paradigm of security has recently been introduced into cryptography with the emergence of the ideas of quantum key distribution and quantum cryptography. While classical cryptography employs various mathematical techniques to restrict eavesdroppers from learning the contents of encrypted messages, in quantum cryptography the information is protected by the laws of physics.

Taxonomy and control measures of SPAM and SPIM

In this age of electronic money transactions, the opportunities for electronic crime expanded at the same rate as ever expanding rise of on-line services. With world becoming a global village, crime over the internet transcends no boundaries, borders or jurisdictions. This paper critically examines the available literature on spam, and the control measures available to control spam. This study is followed by the literature overview related to mobility of devices and how the application of mobile technologies as communication medium has impacted the handling of spam. The conclusion of this literature review with proposed direction of study is summarized.

Reversible and blind database watermarking using difference expansion

Database watermarking has received significant research attention in the current decade. Although, almost all watermarking models have been either irreversible (the original relation cannot be restored from the watermarked relation) and/or non-blind (requiring original relation to detect the watermark in watermarked relation). This model has several disadvantages over reversible and blind watermarking (requiring only watermarked relation and secret key from which the watermark is detected and original relation is restored) including inability to identify rightful owner in case of successful secondary watermarking, inability to revert the relation to original data set (required in high precision industries) and requirement to store unmarked relation at a secure secondary storage. To overcome these problems, we propose a watermarking scheme that is reversible as well as blind. We utilize difference expansion on integers to achieve reversibility. The major advantages provided by our scheme are reversibility to high quality original data set, rightful owner identification, resistance against secondary watermarking attacks, and no need to store original database at a secure secondary storage.

Precise relative clock synchronization for distributed control using TSC registers

Precise clock synchronization is essential in emerging time-critical distributed control systems operating over computer networks where the clock synchronization requirements are mostly focused on relative clock synchronization and high synchronization precision. Existing clock synchronization techniques such as the Network Time Protocol (NTP) and the IEEE 1588 standard can be difficult to apply to such systems because of the highly precise hardware clocks required, due to network congestion caused by a high frequency of synchronization message transmissions, and high overheads. In response, we present a Time Stamp Counter based precise Relative Clock Synchronization Protocol (TSC-RCSP) for distributed control applications operating over local-area networks (LANs). In our protocol a software clock based on the TSC register, counting CPU cycles, is adopted in the time clients and server. TSC-based clocks offer clients a precise, stable and low-cost clock synchronization solution. Experimental results show that clock precision in the order of 10~microseconds can be achieved in small-scale LAN systems. Such clock precision is much higher than that of a processor's Time-Of-Day clock, and is easily sufficient for most distributed real-time control applications over LANs.

Security and Privacy in Vehicular Ad-Hoc Networks : Survey and the Road Ahead

Vehicular Ad-hoc Networks (VANETs) can make roads safer, cleaner, and smarter. It can offer a wide range of services, which can be safety and non-safety related. Many safety-related VANETs applications are real-time and mission critical, which would require strict guarantee of security and reliability. Even non-safety related multimedia applications, which will play an important role in the future, will require security support. Lack of such security and privacy in VANETs is one of the key hindrances to the wide spread implementations of it. An insecure and unreliable VANET can be more dangerous than the system without VANET support. So it is essential to make sure that “life-critical safety” information is secure enough to rely on. Securing the VANETs along with appropriate protection of the privacy drivers or vehicle owners is a very challenging task. In this work we summarize the attacks, corresponding security requirements and challenges in VANETs. We also present the most popular generic security policies which are based on prevention as well detection methods. Many VANETs applications require system-wide security support rather than individual layer from the VANETs’ protocol stack. In this work we will review the existing works in the perspective of holistic approach of security. Finally, we will provide some possible future directions to achieve system-wide security as well as privacy-friendly security in VANETs.