Kemal Bicakci

Kemal Bicakci
TOBB University of Economics and Technology · Deparment of Computer Engineering

PhD

About

84
Publications
24,700
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1,161
Citations

Publications

Publications (84)
Article
Purpose With the irresistible growth in digitization, data backup policies become essential more than ever for organizations seeking to improve reliability and availability of organizations' information systems. However, since backup operations do not come free, there is a need for a data-informed policy to decide how often and which type of backup...
Conference Paper
ModSecurity is an open-source web application firewall. The correct configuration is key to its effective operation but could be tricky since usability flaws could lead to errors and misconfiguration, threatening the security and availability. In this study, we first conduct the usability inspection of ModSecurity through a hybrid approach consisti...
Article
Full-text available
The F-layout was introduced in 1955 and eventually enforced as a national standard as a replacement to the popular QWERTY keyboard layout in Turkey. In a more recent work, another alternative (E-layout) was developed for Turkish language and argued to be faster and more comfortable than the F-layout. However, there has not been any empirical eviden...
Preprint
The F-layout was introduced in 1955 and eventually enforced as a national standard as a replacement to the popular QWERTY keyboard layout in Turkey. In a more recent work, another alternative (E-layout) was developed for Turkish language and argued to be faster and more comfortable than the F-layout. However, there has not been any empirical eviden...
Conference Paper
Full-text available
Vulnerability scanning is a fundamental step for assuring system security. It is also an integral component of IT system risk assessment to manage the identified vulnerabilities in a timely and prioritized way. It is critical that the tools for vulnerability scanning are usable so that cybersecurity practitioners get the most out of them. In this w...
Article
Full-text available
Key pre-distribution schemes accommodate secure connectivity by establishing pairwise keys between nodes. However, ensuring security for all communication links of a wireless sensor network is non-trivial due to the memory limitations of the nodes. If some of the links are not available due to the lack of a primary security association between the...
Article
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Human-interaction proofs (HIPs) are used to mitigate automated attacks. Security and usability have always been a critical problem for HIPs, especially when “accessibility” is a system requirement. Pure-text HIPs are more favorable from the usability perspective, but they are not secure. Audio HIPs usually cannot reliably distinguish attacks from l...
Article
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With the advent of cloud technologies, there is a growing number of easy-to-use services to store files and share them with other cloud users. Cloud service providers try to convince users to trust their services and encourage them to store personal files or corporate documents on their servers. However, both security conscious personal and coopera...
Article
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Even though purely text-based Human Interaction Proofs (HIPs) have desirable usability and accessibility attributes; they could not overcome the security problems yet. Given the fact that fully automated techniques to generate pure-text HIPs securely do not exist, we propose leveraging human computation for this purpose. We design and implement a s...
Article
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In a typical Wireless Sensor Network (WSN) application, the basic communication service is the transportation of the data collected from sensors to the base station. For prolonging the network lifetime, energy efficiency should be one of the primary attributes of such a service. The amount of data transmitted by a node usually depends on how much l...
Conference Paper
Android Lock Pattern is popular as a screen lock method on mobile devices but it cannot be used directly over the Internet for user authentication. In our work, we carefully adapt Android Lock Pattern to satisfy the requirements of remote authentication and introduce a new pattern based method called charPattern. Our new method allows dual-mode of...
Article
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Significant portion of contemporary computer users are children, who are vulnerable to threats coming from the Internet. To protect children from such threats, in this study, we investigate how successfully typing data can be used to distinguish children from adults. For this purpose, we collect a dataset comprising keystroke data of 100 users and...
Article
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Authentication proxies, which store users' secret credentials and submit them to servers on their behalf, offer benefits with respect to security of the authentication and usability of credential management. However, as being a service that is not in control of users, one important problem they suffer is the trust problem; how users trust that thei...
Conference Paper
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Human-Interaction Proof (HIP) systems are widely used to prevent malicious acts of abusers. Legitimate users, however, are not satisfied with their ease of use. The response of Google to the complaints of difficulty in solving audio reCAPTCHAs was to introduce a much simpler version. But now we are back at the position where we have an accessible a...
Article
Route diversity improves the security of Wireless Sensor Networks (WSNs) against adversaries attempting to obtain sensitive sensor data. By limiting the fraction of data relayed over each link and/or routed through each relay node, route diversity can be achieved, thus, extracting useful information from the network is rendered more challenging for...
Article
The paradigm of sensors organized in a multi-hop wireless network has been recognized as a cost effective way to satisfy the real-time sensing and communication needs of a smart grid. For wireless sensor networks, one of the most important design goals is the maximization of network lifetime. Scalability, on the other hand, is also of utmost import...
Conference Paper
Full-text available
Optimization of flows to maximize Wireless Sensor Network (WSN) lifetime is a problem already investigated in various aspects. However, most studies ignored the effects of finite bandwidth. As source data rate of sensor nodes increases, flow patterns that balance energy dissipation optimally might need more bandwidth than available. As a result, ig...
Conference Paper
Full-text available
Optimization of flows to maximize Wireless Sensor Network (WSN) lifetime is a problem already investigated in various aspects. However, most studies ignored the effects of finite bandwidth. As source data rate of sensor nodes increases, flow patterns that balance energy dissipation optimally might need more bandwidth than available. As a result, ig...
Article
Full-text available
Current mobile authentication solutions put a cognitive burden on users to detect and avoid Man-In-The-Middle attacks. In this paper, we present a mobile authentication protocol named Mobile-ID which prevents Man-In-The-Middle attacks without relying on a human in the loop. With Mobile-ID, the message signed by the secure element on the mobile devi...
Conference Paper
Full-text available
In wireless sensor networks, nodes having limited battery resources convey data to an energy-unconstrained base station. The amount of data transmitted by a node usually depends on how much local processing is performed. In other words, more computation on a node means less communication with the base station and vice versa. Hence improving energy...
Conference Paper
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Users generally choose weak passwords which can be easily guessed. On the other hand, adoption of alternatives to text passwords has been slow due to cost and usability factors. We acknowledge that incumbent passwords remain difficult to beat and introduce in this study Type&Click (T&C), a hybrid scheme supporting text passwords with the graphical...
Article
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Server-side authenticated key-establishment protocols are characterized by placing a heavy workload on the server. We propose LAKE: a new protocol that enables amortizing servers' workload peaks by moving most of the computational burden to the clients. We provide a formal analysis of the LAKE protocol under the Canetti-Krawczyk model and prove it...
Article
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In wireless sensor networks, multi-path routing is proposed for energy balancing which prolongs the network lifetime as compared to single-path routing where utilization of a single route between a source node and the base station results in imbalanced energy dissipation. While it is evident that increasing the number of routing paths mitigates the...
Conference Paper
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In this paper, we investigate the effects of mobility on the energy dissipation characteristics of wireless networks. We construct a Linear Programming (LP) framework that jointly captures data routing, mobility, and energy dissipation aspects and explore the design space by performing numerical analysis using the developed LP framework. Our result...
Article
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Transmission power control has paramount importance in the design of energy-efficient wireless sensor networks (WSNs). In this paper, we systematically explore the effects of various transmission power control strategies on WSN lifetime with an emphasis on discretization of power levels and strategies for transmission power assignment. We investiga...
Article
In this paper we consider neighbor sensor networks which are defined as multiple wireless sensor networks under the administration of different authorities but located physically on the same area or close to each other. We construct a Linear Programming framework to characterize the cooperation of neighbor sensor networks in comparison to non-coope...
Conference Paper
Full-text available
The occurrence of unidirectional links in wireless sensor networks (WSNs) is an inherent feature of wireless communication. Transceiver characteristics, asymmetric interference, and many other properties of the electromagnetic propagation environment result in link unidirectionality, however, transmission power heterogeneity is the dominant factor...
Conference Paper
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It is well-known that in wireless sensor networks using minimum-energy paths to transfer data from sensor nodes to base station is not an energy-balancing option and not the optimal solution if lifetime, defined as the duration till the first node in the network exhausts all its energy, is of concern. However, the net effect of minimum-energy routi...
Conference Paper
Full-text available
Maximization of lifetime is one of the most important design goals in Wireless sensor networks (WSN). On the other hand, for any given network design problem scalability is also of utmost importance. Yet, these two design goals are acting against each other. In this study, a characterization of achievable network lifetime as a function of the degre...
Conference Paper
Full-text available
Most of the data transfer mechanisms designed for wireless sensor networks (WSNs) work only on bidirectional links, yet, there are some mechanisms capable of utilizing unidirectional links which have been caused by transmission power heterogeneity. Employment of a multi-hop reverse path for acknowledgement delivery is the key concept in these desig...
Article
Keystroke Dynamics, which is a biometric characteristic that depends on typing style of users, could be a viable alternative or a complementary technique for user authentication if tolerable error rates are achieved. Most of the earlier studies on Keystroke Dynamics were conducted with irreproducible evaluation conditions therefore comparing their...
Article
Full-text available
Our agenda is two-fold. First, we introduce and give a technical description of gridWord, a novel knowledge-based authentication mechanism involving elements of both text and graphical passwords. It is intended to address a new research challenge arising from the evolution of Internet access devices, and which may arguably be viewed as motivating a...
Conference Paper
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Physical attacks, which aim to render one or more sensor nodes non-operational by physically capturing and destroying them, are among the most serious security threats in Wireless Sensor Networks (WSNs). In case of dense deployment (a desirable property in the design of WSNs) multiple sensor nodes acquire redundant (highly correlated) data. As a re...
Article
In the context of wireless sensor networks, computation/communication tradeoffs may appear in many aspects of the system design. In this paper, we present a linear programming framework to guide designers in effectively using these tradeoffs for prolonging network lifetime. To investigate the tradeoff in more concrete terms, as our representative p...
Article
Full-text available
One of the most popular aids adopted by users to reduce the pain suffered from the use of passwords is browsers' autocomplete feature. This feature, caching username and password after getting the user consent and using them later for automatic completion, is available in all modern browsers but communication with the user asking consent is impleme...
Article
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ecent developments in low-cost CMOS cameras have created the opportunity of bringing imaging capabilities to sensor networks. Various visual sensor platforms have been developed with the aim of integrating visual data to wireless sensor applications. The objective of this article is to survey current visual sensor platforms according to in-network...
Conference Paper
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We carry out a hybrid lab and field study of a password manager program, and report on usability and security. Our study explores iPMAN, a browser-based password manager that in addition uses a graphical password scheme for the master password. We present our findings as a set of observations and insights expected to be of interest both to those ex...
Article
Full-text available
The lifetime of wireless sensor networks (WSNs) is optimized if the traffic within the network is adjusted in a way that all nodes dissipate their energies in a balanced fashion. To balance the energy dissipation, nodes split their flows and these flows are forwarded to different nodes acting as relays. In consequence some nodes have too many incom...
Article
Full-text available
Wireless sensor networks (WSNs) are used to obtain information from the surrounding areas and collected data is reported to the base station through wireless links. In certain scenarios ongoing transmissions within the network need to be concealed so that no information is leaked beyond a vulnerable area. Such a concealment effort necessitates tran...
Conference Paper
In recent years phishing attacks have become one of the most important problems of online security. Aza Raskin, the creative lead of Mozilla Firefox team, proposed a new type of phishing attack, “tabnabbing attack” as he names it. The attack is different from classical phishing attacks; while classical attacks rely on deception of users with a simi...
Conference Paper
Full-text available
In some wireless sensor network applications like precision agriculture, the network area is divided into a number of well-defined regions (spatial granules) and for each spatial granule a separate measurement is made. In performing the task of collecting the data pertaining to these measurements, there is an inherent tradeoff between number of spa...
Article
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This is a position paper on our views on security aspects of Wireless Multimedia Sensor Networks (Secure WMSNs). It is meant to serve as a brief survey. But, more importantly, it gives a perspective on how we foresee the fu-ture of this research area, its main challenges, and its future trends. We believe that this paper will spur new discussions a...
Article
In wireless sensor networks nodes forward the data they acquire from the environment towards the base station by relaying through multiple intermediate sensor nodes used as relays. If multiple sensor networks are deployed in close proximity then they can help each others’ data forwarding so that all parties involved in such cooperation benefit from...
Article
Full-text available
A wireless sensor network consists of at least one base station and multiple sensor nodes. These nodes are battery powered and are expected to operate for a long time therefore energy efficiency becomes a crucial design objective. Optimization of network lifetime can be achieved by balancing the energy consumption within the network. This requires...
Article
Full-text available
In this letter, we present a mixed binary linear programming framework to investigate the impact of one-time energy costs on the overall system lifetime in wireless sensor networks. We use public-key cryptography as our representative one-time initialization operation. We show that the effect of public-key cryptography on optimal routes selection d...
Conference Paper
Full-text available
Today, most Internet applications still establish user authentication with tradi-tional text based passwords. Designing a secure as well as a user-friendly password-based method has been on the agenda of security researchers for a long time. On one hand, there are password manager programs which facilitate generating site-specific strong passwords...
Article
IEEE 802.11 access points deployed in shopping malls, university campuses, crowded streets, airports, and many other locations provide ubiquitous Internet access to millions of stations. However, these hot spots are vulnerable to Denial-of-Service (DoS) attacks due to the broadcast nature of wireless communication. It does not require specialized h...
Conference Paper
Full-text available
Click based graphical passwords that use background images suffer from hot-spot problem. Previous graphical password schemes based on recognition of images do not have a sufficiently large password space suited for most Internet applications. In this paper, we propose two novel graphical password methods based on recognition of icons to solve the h...
Conference Paper
Computational and security advantages of one-time signatures come together with their length restrictions. In most applications, one-time signature should be accompanied with one-time public key(s) to enable multiple signing with a single certified public key. This is why most of the time decreasing the size of one-time signature at a cost of large...
Article
Full-text available
In click-based graphical password schemes that allow arbitrary click locations on image, a click should be verified as correct if it is close within a predefined distance to the originally chosen location. This condition should hold even when for security reasons the password hash is stored in the system, not the password itself. To solve this prob...
Conference Paper
One of the most promising technologies to enhance the quality of life of quadriplegia patients is smart home environments. Security has a paramount importance for all health information systems, but it is generally overlooked until a major security breach occurs. Especially in an application specifically targeting people with disabilities, ignoring...
Article
Proxy signatures are useful constructions in grid computing, mobile agents and many other emerging applications. In a recent work [Huaxiong Wang and Josef Pieprzyk: Efficient One-Time Proxy Signatures. Proc. ASIACRYPT'03, LNCS 2894, Springer 2003.], Wang and Pieprzyk proposed a one-time signature scheme which allows full delegation to a proxy with...
Chapter
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How to Capture and Preserve Digital Evidence Securely? For the investigation and prosecution of criminal activities that involve computers, digital evidence collected in the crime scene has a vital importance. On one side, it is a very challenging task for forensics professionals to collect them without any loss or damage. On the other, there is th...
Conference Paper
Full-text available
We propose a secure one-time sensor scheme that is highly resistant to forged messages and replay message attacks. A sensor in a one-time sensor network transmits only a single message in its life time but retransmits messages from other sensors to provide message routing. The only security-specific computational capability required from a one-time...
Article
Full-text available
Common occurrence of server overload and the threat of denial-of-service (DoS) attacks makes highly desirable to improve the performance and DoS resistance of SSL handshakes. In this paper, we tackle these two related problems by proposing reverse SSL, an extension in which the server is relieved from the heavy public key decryption operation and a...
Conference Paper
Full-text available
The research area of very large scale wireless sensor net- works made of low-cost sensors is gaining a lot of interest as witnessed by the large number of published papers. The se- curity aspects of such networks are addressed as well, and in particular many security papers investigating the secu- rity aspects of such networks make important assump...
Conference Paper
Dealing with captured nodes is generally accepted as the most difficult challenge to wireless sensor network security. By utilizing the low-cost property of sensor nodes, we introduce the novel concept of one-time sensors to mitigate node-capture attacks. The basic idea is to load each sensor with only one cryptographic token so that the captured n...
Conference Paper
In the audit process of Internet activities of users in a local area network, one of the most difficult problems is the problem of source authentication i.e. establishing securely the identity of the owner of the records. The problem cannot be solved by user authentication only because of the inherited security deficiencies in the structure of Inte...
Conference Paper
Mobile and ad-hoc networks allow businesses to provide a new range of applications and services and at the same time they introduce new constraints that have important effects on the way in which security primitives must be designed. This is challenging because it translates to a demand of richer and more flexible security primitives that often nee...
Article
It is well known that excessive computational demands of public key cryptography have made its use limited especially when constrained devices are of concern. To reduce the costs of generating public key signatures one viable method is to employ a third party; the server. In open networks, getting help from a verifiable-server has an advantage over...
Conference Paper
Full-text available
In a traditional PKI, the trust associated with a public key is expressed in binary either by 0 or 1. Alternatively, several authors have proposed trust metrics to evaluate the confidence afforded by a public key. However their work has a static point of view and does not take into account the issue of public key revocation. In this paper, we make...
Conference Paper
Just like PKI, used to support public key certificates, Privilege Management Infrastructure (PMI) is built to provide a foundation Just like PKI, used to support public key certificates, Privilege Management Infrastructure (PMI) is built to provide a foundation to employ attribute certificates. Although most of the PKI ideas can be applied to PMI a...