Consider a scenario where a server S shares a symmetric key kU with each user U. Building on a 2-party solution of Bohli et al., we describe an authenticated 3-party key establishment which remains secure if a computational Bilinear Diffie Hellman problem is hard or the server is uncorrupted. If the BDH assumption holds during a protocol execution, but is invalidated later, entity authentication and integrity of the protocol are still guaranteed. Key establishment protocols based on hardness assumptions, such as discrete logarithm problem (DLP) and integer factorization problem (IFP) are vulnerable to quantum computer attacks, whereas the protocols based on other hardness assumptions, such as conjugacy search problem and decomposition search problem can resist such attacks. The existing protocols based on the hardness assumptions which can resist quantum computer attacks are only passively secure. Compilers are used to convert a passively secure protocol to an actively secure protoc ol. Compilers involve some tools such as, signature scheme and a collision-resistant hash function. If there are only passively secure protocols but not a signature scheme based on same assumption then the application of existing compilers requires the use of such tools based on different assumptions. But the introduction of new tools, based on different assumptions, makes the new actively secure protocol rely on more than one hardness assumptions. We offer an approach to derive an actively secure two-party protocol from a passively secure two-party protocol without introducing further hardness assumptions. This serves as a useful formal tool to transform any basic algebric method of public key cryptography to the real world applicaticable cryptographic scheme. In a recent preprint, Vivek et al. propose a compiler to transform a passively secure 3-party key establishment to a passively secure group key establishment. To achieve active security, they apply this compiler to Joux's / protoc ol and apply a construction by Katz and Yung, resulting in a 3-round group key establishment. In this reserach, we show how Joux's protocol can be extended to an actively secure group key establishment with two rounds. The resulting solution is in the standard model, builds on a bilinear Diffie-Hellman assumption and offers forward security as well as strong entity authentication. If strong entity authentication is not required, then one half of the participants does not have to send any message in the second round, which may be of interest for scenarios where communication efficiency is a main concern. / by Kashi Neupane. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.

IEEE 802.11 networks successfully satisfy high data demands and are cheaper compared to cellular networks. Modern mobile computers and phones are equipped with 802.11 and are VoIP capable. Current network designs do not dynamically accommodate changes in the usage. We propose a dynamic power control algorithm that provides greater capacity within a limited geographic region. Most other power algorithms necessitate changes in 802.11 requiring hardware changes. Proposed algorithm only requires firmware updates to enable dynamic control of APs transmit power. We use earlier studies to determine the limit of the number of users to optimize power. By lowering transmit power of APs with large number of users, we can effectively decrease the cell size. The resulting gap is then covered by dynamically activating additional APs. This also provides greater flexibility and reduces the network planning costs. / by Serkan Dural. / Thesis (M.S.C.S.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

University of Macau / Faculty of Science and Technology. / Department of Computer and Information Science

The Google Android mobile phone platform is one of the dominant smartphone operating systems on the market. The open source Android platform allows developers to take full advantage of the mobile operation system, but also raises significant issues related to malicious applications (Apps). The popularity of Android platform draws attention of many developers which also attracts the attention of cybercriminals to develop different kinds of malware to be inserted into the Google Android Market or other third party markets as safe applications. In this thesis, we propose to combine permission, API (Application Program Interface) calls and function calls to build a Heuristic-­Based framework for the detection of malicious Android Apps. In our design, the permission is extracted from each App’s profile information and the APIs are extracted from the packed App file by using packages and classes to represent API calls. By using permissions, API calls and function calls as features to characterize each of Apps, we can develop a classifier by data mining techniques to identify whether an App is potentially malicious or not. An inherent advantage of our method is that it does not need to involve any dynamic tracking of the system calls but only uses simple static analysis to find system functions from each App. In addition, Our Method can be generalized to all mobile applications due to the fact that APIs and function calls are always present for mobile Apps. Experiments on real-­world Apps with more than 1200 malwares and 1200 benign samples validate the algorithm performance. Research paper published based on the work reported in this thesis: Naser Peiravian, Xingquan Zhu, Machine Learning for Android Malware Detection Using Permission and API Calls, in Proc. of the 25th IEEE International Conference on Tools with Artificial Intelligence (ICTAI) – Washington D.C, November 4-­6, 2013. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2013.

A social network is a structure of individuals and organizations, which are connected by one or more types of interdependency, such as friendship, affinity, common interests or knowledge. Social networks use Web 2.0 technology, which is mostly based on a service-oriented architecture. We are studying patterns for social networks in this environment. A pattern is an encapsulated solution to a software problem in a given context, secure threats are possible in this context. We present a collection of patterns associated with the most important aspects of social networks, with emphasis on controlling the actions of the users of these networks. / by Carolina Marina. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.

Multi-hop wireless networks are infrastructure-less networks consisting of mobile or stationary wireless devices, which include multi-hop wireless mesh networks and multi-hop wireless sensor networks. These networks are characterized by limited bandwidth and energy resources, unreliable communication, and a lack of central control. These characteristics lead to the research challenges of multi-hop wireless networks. Building up routing schemes with good balance among the routing QoS (such as reliability, cost, and delay) is a paramount concern to achieve high performance wireless networks. These QoS metrics are internally correlated. Most existing works did not fully utilize this correlation. We design a metric to balance the trade-off between reliability and cost, and build up a framework of utility-based routing model in multi-hop wireless networks. This dissertation focuses on the variations with applications of utility-based routing models, designing new concepts, and developing new algorithms for them. A review of existing routing algorithms and the basic utility-based routing model for multi-hop wireless networks has been provided at the beginning. An efficient algorithm, called MaxUtility, has been proposed for the basic utility-based routing model. MaxUtility is an optimal algorithm that can find the best routing path with the maximum expected utility. / Various utility-based routing models are extended to further enhance the routing reliability while reducing the routing overhead. Besides computing the optimal path for a given benefit value and a given source-destination pair, the utility-based routing can be further extended to compute all optimal paths for all possible benefit values and/or all source-destination pairs. Our utility-based routing can also adapt to different applications and various environments. In the self-organized environment, where network users are selfish, we design a truthful routing, where selfish users have to tell the truth in order to maximize their utilities. We apply our utility-based routing scheme to the data-gathering wireless sensor networks, where a routing scheme is required to transmit data sensed by multiple sensor nodes to a common sink node. / by Mingming Lu. / Vita. / University Library's copy lacks signatures of Supervisory Committee. / Thesis (Ph.D.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, FL : 2008 Mode of access: World Wide Web.

To ensure that a system is robust and will continue operation even when facing disruptive or traumatic events, we have created a methodology for system architects and designers which may be used to locate risks and hazards in a design and enable the development of more robust and resilient system architectures. It uncovers design vulnerabilities by conducting a complete exploration of a systems’ component operational state space by observing the system from multi-dimensional perspectives and conducts a quantitative design space analysis by means of probabilistic risk assessment using Bayesian Networks. Furthermore, we developed a tool which automated this methodology and demonstrated its use in an assessment of the OCTT PHM communication system architecture. To boost the robustness of a wireless communication system and efficiently allocate bandwidth, manage throughput, and ensure quality of service on a wireless link, we created a wireless link management architecture which applies sensor fusion to gather and store platform networked sensor metrics, uses time series forecasting to predict the platform position, and manages data transmission for the links (class based, packet scheduling and capacity allocation). To validate our architecture, we developed a link management tool capable of forecasting the link quality and uses cross-layer scheduling and allocation to modify capacity allocation at the IP layer for various packet flows (HTTP, SSH, RTP) and prevent congestion and priority inversion. Wireless sensor networks (WSN) are vulnerable to a plethora of different fault types and external attacks after their deployment. To maintain trust in these systems and increase WSN reliability in various scenarios, we developed a framework for node fault detection and prediction in WSNs. Individual wireless sensor nodes sense characteristics of an object or environment. After a smart device successfully connects to a WSN’s base station, these sensed metrics are gathered, sent to and stored on the device from each node in the network, in real time. The framework issues alerts identifying nodes which are classified as faulty and when specific sensors exceed a percentage of a threshold (normal range), it is capable of discerning between faulty sensor hardware and anomalous sensed conditions. Furthermore we developed two proof of concept, prototype applications based on this framework. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2013.

The SSL/TLS is the main protocol used to provide secure data connection between a client and a server. The main concern of using this protocol is to avoid the secure connection from being breached. Computer systems and their applications are becoming more complex and keeping these secure connections between all the connected components is a challenge. To avoid any new security flaws and protocol connections weaknesses, the SSL/TLS protocol is always releasing newer versions after discovering security bugs and vulnerabilities in any of its previous version. We have described some of the common security flaws in the SSL/TLS protocol by identifying them in the literature and then by analyzing the activities from each of their use cases to find any possible threats. These threats are realized in the form of misuse cases to understand how an attack happens from the point of the attacker. This approach implies the development of some security patterns which will be added as a reference for designing secure systems using the SSL/TLS protocol. We finally evaluate its security level by using misuse patterns and considering the threat coverage of the models. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

In the design of two-party key exchange it is common to rely on a Die-Hellman type hardness assumption in connection with elliptic curves. Unlike the case of nite elds, breaking multiple instances of the underlying hardness assumption is here considered substantially more expensive than breaking a single instance. Prominent protocols such as SPEKE [12] or J-PAKE [8, 9, 10] do not exploit this, and here we propose a password-authenticated key establishment where the security builds on the intractability of solving a specied number of instances v of the underlying computational problem. Such a design strategy seems particularly interesting when aiming at long-term security guarantees for a protocol, where expensive special purpose equipment might become available to an adversary. In this thesis, we give one protocol for the special case when v = 1 in the random oracle model, then we provide the generalized protocol in the random oracle model and a variant of the generalized protocol in the standard model for v being a polynomial of the security parameter `. / by WeiZheng Gao. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2012. Mode of access: World Wide Web.

Fung Chun-Kan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 105-114). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.iv / List of Figures --- p.viii / List of Tables --- p.x / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivations and Objectives --- p.1 / Chapter 1.2 --- Authentication Protocol --- p.3 / Chapter 1.3 --- Security Technologies --- p.5 / Chapter 1.3.1 --- Cryptography --- p.5 / Chapter 1.3.2 --- Digital Certificate --- p.7 / Chapter 1.3.3 --- One-way Hash Function --- p.8 / Chapter 1.3.4 --- Digital Signature --- p.9 / Chapter 1.4 --- Thesis Organization --- p.9 / Chapter 2 --- Related Work --- p.11 / Chapter 2.1 --- Introduction --- p.11 / Chapter 2.2 --- Authentication and Key Establishment Protocols --- p.11 / Chapter 2.3 --- Denial-of-Service Attack Handling Methods --- p.15 / Chapter 2.4 --- Attacks on Authentication and Key Establishment Protocol --- p.18 / Chapter 2.4.1 --- Denial-of-Service Attack --- p.19 / Chapter 2.4.2 --- Replay Attack --- p.19 / Chapter 2.4.3 --- Man-in-the middle Attack --- p.21 / Chapter 2.4.4 --- Chosen-text Attack --- p.22 / Chapter 2.4.5 --- Interleaving Attack --- p.23 / Chapter 2.4.6 --- Reflection Attack --- p.25 / Chapter 2.5 --- Summary --- p.27 / Chapter 3 --- A DoS-resistant Authentication and Key Establishment Protocol --- p.29 / Chapter 3.1 --- Introduction --- p.29 / Chapter 3.2 --- Protocol Notations --- p.30 / Chapter 3.3 --- Protocol Descriptions --- p.30 / Chapter 3.4 --- An Improved Client Puzzle Protocol --- p.37 / Chapter 3.4.1 --- Review of Juels-Brainard Protocol --- p.37 / Chapter 3.4.2 --- Weaknesses of Juels-Brainard Protocol and Proposed Improvements --- p.39 / Chapter 3.4.3 --- Improved Client Puzzle Protocol --- p.42 / Chapter 3.5 --- Authentication Framework --- p.43 / Chapter 3.5.1 --- Client Architecture --- p.44 / Chapter 3.5.2 --- Server Architecture --- p.47 / Chapter 3.6 --- Implementations --- p.49 / Chapter 3.6.1 --- Software and Programming Tools --- p.49 / Chapter 3.6.2 --- The Message Formats --- p.50 / Chapter 3.5.3 --- Browser Interface --- p.51 / Chapter 3.6.4 --- Calculation of the Difficulty Level --- p.53 / Chapter 3.6.5 --- "(C, t) Non-Existence Verification" --- p.56 / Chapter 3.7 --- Summary --- p.57 / Chapter 4 --- Security Analysis and Formal Proof --- p.58 / Chapter 4.1 --- Introduction --- p.58 / Chapter 4.2 --- Security Analysis --- p.59 / Chapter 4.2.1 --- Denial-of-Service Attacks --- p.59 / Chapter 4.2.2 --- Replay Attacks.........； --- p.60 / Chapter 4.2.3 --- Chosen-text Attacks --- p.60 / Chapter 4.2.4 --- Interleaving Attacks --- p.61 / Chapter 4.2.5 --- Others --- p.62 / Chapter 4.3 --- Formal Proof Methods --- p.62 / Chapter 4.3.1 --- General-purpose Specification Languages and Verification Tools --- p.62 / Chapter 4.3.2 --- Expert System Approach --- p.63 / Chapter 4.3.3 --- Modal Logic Approach --- p.64 / Chapter 4.3.4 --- Algebraic Term-Rewriting Approach --- p.66 / Chapter 4.4 --- Formal Proof of the Proposed Protocol --- p.66 / Chapter 4.4.1 --- Notations --- p.67 / Chapter 4.4.2 --- The Proof --- p.68 / Chapter 4.5 --- Summary --- p.73 / Chapter 5 --- Experimental Results and Analysis --- p.75 / Chapter 5.1 --- Introduction --- p.75 / Chapter 5.2 --- Experimental Environment --- p.75 / Chapter 5.3 --- Experiments --- p.77 / Chapter 5.3.1 --- Computational Performance of the Puzzle Solving Operation at different Difficulty Levels --- p.77 / Chapter 5.3.2 --- Computational Performance of the Puzzle Generation and Puzzle Solution Verification --- p.79 / Chapter 5.3.3 --- Computational Performance of the Protocol Cryptographic Operations --- p.82 / Chapter 5.3.4 --- Computational Performance of the Overall Protocol Session --- p.84 / Chapter 5.3.5 --- Impact on the Server Load without Client Puzzles --- p.85 / Chapter 5.3.6 --- Impact on the Server Load with Client Puzzles --- p.88 / Chapter 5.3.7 --- Impact on the Server Response Time from the Puzzles --- p.97 / Chapter 5.4 --- Summary --- p.100 / Chapter 6 --- Conclusion and Future Work --- p.101 / Chapter 6.1 --- Concluding Remarks --- p.101 / Chapter 6.2 --- Contributions --- p.103 / Chapter 6.3 --- Future Work --- p.104 / Bibliography --- p.105