2014 |
Kocsis, Jin (Wei) A Biologically Inspired Hierarchical Cyber-Physical Integrated Security Analysis Framework for Smart Grids PhD Thesis University of Toronto, 2014. Abstract | BibTeX | Tags: CPS, PhD thesis, smart grid, thesis @phdthesis{WeiPhDThesis14, title = {A Biologically Inspired Hierarchical Cyber-Physical Integrated Security Analysis Framework for Smart Grids}, author = {Jin (Wei) Kocsis}, year = {2014}, date = {2014-06-18}, address = {Toronto, Ontario}, school = {University of Toronto}, abstract = {The last few years have witnessed the radical transformation in structure and functionality of electrical energy systems. Such systems were traditionally executed in the physical world and are now also cyber-enabled. This cyber-enabled energy system, called smart grid, can be envisioned as the marriage of information technology with the electricity network. While its increased dependence on cyber infrastructure aims to enable greater reliability, efficiency and capacity of power delivery, this reliance also creates a host of unfamiliar vulnerabilities. Due to the highly integrated and connected nature of smart grids, it is important to account for their salient cyber-physical coupling when making critical design decisions and identifying solutions to promote security. In this dissertation, we present a flocking-theory inspired dynamical systems paradigm to model smart grid cyber-physical interactions related to smart grid stability. Such a biologically-inspired framework enables the convenient description of (discrete) cyber and (analog) physical couplings. Through this paradigm, we demonstrate real-time cyber-physical integrated control and communication strategies using “wisely”-placed phasor measurement units and energy storages to re-stabilize a smart grid system under various forms of cyber and physical attacks. Our research has evolved in three stages. We first propose a multi-agent dynamical systems paradigm to model the cyber-physical interactions related to smart grid stability. In our multi-agent framework each node, representing both electrical and information system components, is modeled as having dynamics that synergistically describe physical and information couplings with neighboring agents. Inspired by the analogy between the flocking behavior in the nature and the stability of the cyber-enabled synchronous generators, We develop a flocking-based scheme to formulate the cyber-physical integrated action for each agent. It is clear from our analysis framework that redundant cyber information acquisition and use increases risks of cyber-attack whereby indiscriminate cyber-dependence and -connectivity increases attack scope and impact. To address this problem, in the second stage, we extend the multi-agent paradigm to a two-tier hierarchical framework by effectively leveraging physical couplings between the agents and identifying the critical ones that increase vulnerability to cyber- or physical- attack. With the developed hierarchical framework, the cyber information redundancy is reduced by only leveraging cyber coupling at critical agents. In the context of the hierarchical framework, we analyze the physical impact of cyber attack. We focus on two major attacks widely effecting the smart grid, attacks on timely data delivery, such as Denial-of-Service (DoS) attacks, and attacks on information accuracy, such as false data injection attacks. The DoS attack can cause communication delay of critical cyber information and result in significant power delivery disruption. To defend against the DoS attacks, we propose an intelligent multicast routing strategy, called Goal-Seeking Obstacle and Collision Evasion (GOALiE), which is appropriate to smart grids and resilient to DoS attacks. We also develop a novel witness-based cyber-physical protocol whereby physical coherence is leveraged to probe and identify the false data injection on Phasor Measurement Unit (PMU) data and estimate the true information values for attack mitigation.}, keywords = {CPS, PhD thesis, smart grid, thesis}, pubstate = {published}, tppubtype = {phdthesis} } The last few years have witnessed the radical transformation in structure and functionality of electrical energy systems. Such systems were traditionally executed in the physical world and are now also cyber-enabled. This cyber-enabled energy system, called smart grid, can be envisioned as the marriage of information technology with the electricity network. While its increased dependence on cyber infrastructure aims to enable greater reliability, efficiency and capacity of power delivery, this reliance also creates a host of unfamiliar vulnerabilities. Due to the highly integrated and connected nature of smart grids, it is important to account for their salient cyber-physical coupling when making critical design decisions and identifying solutions to promote security. In this dissertation, we present a flocking-theory inspired dynamical systems paradigm to model smart grid cyber-physical interactions related to smart grid stability. Such a biologically-inspired framework enables the convenient description of (discrete) cyber and (analog) physical couplings. Through this paradigm, we demonstrate real-time cyber-physical integrated control and communication strategies using “wisely”-placed phasor measurement units and energy storages to re-stabilize a smart grid system under various forms of cyber and physical attacks. Our research has evolved in three stages. We first propose a multi-agent dynamical systems paradigm to model the cyber-physical interactions related to smart grid stability. In our multi-agent framework each node, representing both electrical and information system components, is modeled as having dynamics that synergistically describe physical and information couplings with neighboring agents. Inspired by the analogy between the flocking behavior in the nature and the stability of the cyber-enabled synchronous generators, We develop a flocking-based scheme to formulate the cyber-physical integrated action for each agent. It is clear from our analysis framework that redundant cyber information acquisition and use increases risks of cyber-attack whereby indiscriminate cyber-dependence and -connectivity increases attack scope and impact. To address this problem, in the second stage, we extend the multi-agent paradigm to a two-tier hierarchical framework by effectively leveraging physical couplings between the agents and identifying the critical ones that increase vulnerability to cyber- or physical- attack. With the developed hierarchical framework, the cyber information redundancy is reduced by only leveraging cyber coupling at critical agents. In the context of the hierarchical framework, we analyze the physical impact of cyber attack. We focus on two major attacks widely effecting the smart grid, attacks on timely data delivery, such as Denial-of-Service (DoS) attacks, and attacks on information accuracy, such as false data injection attacks. The DoS attack can cause communication delay of critical cyber information and result in significant power delivery disruption. To defend against the DoS attacks, we propose an intelligent multicast routing strategy, called Goal-Seeking Obstacle and Collision Evasion (GOALiE), which is appropriate to smart grids and resilient to DoS attacks. We also develop a novel witness-based cyber-physical protocol whereby physical coherence is leveraged to probe and identify the false data injection on Phasor Measurement Unit (PMU) data and estimate the true information values for attack mitigation. |
2013 |
Liu, Shan Coordinated Variable Structure Switching Attacks for Smart Grid PhD Thesis Texas A&M University, 2013. Abstract | BibTeX | Tags: CPS, PhD thesis, smart grid, thesis @phdthesis{LiuPhDThesis13, title = {Coordinated Variable Structure Switching Attacks for Smart Grid}, author = {Shan Liu}, year = {2013}, date = {2013-05-01}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {The effective modeling and analysis of large-scale power system disturbances especially those stemming from intentional attack represents an open engineering and research problem. Challenges stem from the need to develop intelligent models of cyber-physical attacks that produce salient disruptions and appropriately describe meaningful cyber-physical interdependencies such that they balance precision, scale and complexity. In our research, we present a foundation for the development of a class of intelligent cyber-physical attacks termed coordinated variable structure switching attacks whereby opponents aim to destabilize the power grid through controlled switching sequence. Such switching is facilitated by cyber attack and corruption of communication channels and control signals of the associated switch(es). We provide methods and theorems to construct such attack models and demonstrate their utility in the simulation of extensive system disturbances. Our proposed class of cyber-physical switching attacks for smart grid systems has the potential to disrupt large-scale power system operation within a short interval of time. Through successful cyber intrusion, an opponent can remotely apply a state dependent coordinated switching sequence on one or more relays and circuit breakers of a power system to disrupt operation. Existence of this switching vulnerability is dependent on the local structure of the power grid. Variable structure systems theory is employed to eectively model the cyber-physical aspects of a smart grid, determine the existence of the vulnerability and construct the destabilizing switching attack sequence. We illustrate the utility of the attack approach assess its impact on the dierent power system test cases including the single machine innite bus power system model and theWestern Electricity Coordinating Council (WECC) 3-machine, 9-bus system through MATLAB/Simulink and PSCAD simulation environment. The results demonstrate the potential of our approach for practical attack. Moreover, we build on our work in several ways. First, we extend the research to demonstrate an approach to mitigation within the variable structure system framework. We demonstrate via small signal analysis how through persistent switching a stable sliding mode can be used to disrupt a dynamical system that seems stable. We also design an approach to vulnerability analysis to assess the feasibility of coordinated variable structure switching attacks. Moreover, we study the performance of our attack construction approach when the opponent has imperfect knowledge of the local system dynamics and partial knowledge of the generator state. Based on the system with modeling errors, we study the performance of coordinated variable structure switching attacks in the presence of state estimation. Finally, we illustrate the concepts of attack model within the multiple switching framework, the cascading failure analysis is employed in the New-England 10-machine, 39-bus power system using MATLAB/Simulink and DSATools simulation environment. Our results demonstrate the potential for coordinated variable structure switching attacks to enable large-scale power system disturbances.}, keywords = {CPS, PhD thesis, smart grid, thesis}, pubstate = {published}, tppubtype = {phdthesis} } The effective modeling and analysis of large-scale power system disturbances especially those stemming from intentional attack represents an open engineering and research problem. Challenges stem from the need to develop intelligent models of cyber-physical attacks that produce salient disruptions and appropriately describe meaningful cyber-physical interdependencies such that they balance precision, scale and complexity. In our research, we present a foundation for the development of a class of intelligent cyber-physical attacks termed coordinated variable structure switching attacks whereby opponents aim to destabilize the power grid through controlled switching sequence. Such switching is facilitated by cyber attack and corruption of communication channels and control signals of the associated switch(es). We provide methods and theorems to construct such attack models and demonstrate their utility in the simulation of extensive system disturbances. Our proposed class of cyber-physical switching attacks for smart grid systems has the potential to disrupt large-scale power system operation within a short interval of time. Through successful cyber intrusion, an opponent can remotely apply a state dependent coordinated switching sequence on one or more relays and circuit breakers of a power system to disrupt operation. Existence of this switching vulnerability is dependent on the local structure of the power grid. Variable structure systems theory is employed to eectively model the cyber-physical aspects of a smart grid, determine the existence of the vulnerability and construct the destabilizing switching attack sequence. We illustrate the utility of the attack approach assess its impact on the dierent power system test cases including the single machine innite bus power system model and theWestern Electricity Coordinating Council (WECC) 3-machine, 9-bus system through MATLAB/Simulink and PSCAD simulation environment. The results demonstrate the potential of our approach for practical attack. Moreover, we build on our work in several ways. First, we extend the research to demonstrate an approach to mitigation within the variable structure system framework. We demonstrate via small signal analysis how through persistent switching a stable sliding mode can be used to disrupt a dynamical system that seems stable. We also design an approach to vulnerability analysis to assess the feasibility of coordinated variable structure switching attacks. Moreover, we study the performance of our attack construction approach when the opponent has imperfect knowledge of the local system dynamics and partial knowledge of the generator state. Based on the system with modeling errors, we study the performance of coordinated variable structure switching attacks in the presence of state estimation. Finally, we illustrate the concepts of attack model within the multiple switching framework, the cascading failure analysis is employed in the New-England 10-machine, 39-bus power system using MATLAB/Simulink and DSATools simulation environment. Our results demonstrate the potential for coordinated variable structure switching attacks to enable large-scale power system disturbances. |
2012 |
Jainsky, Julien Sebastien Defenses Against Covert-Communications in Multimedia and Sensor Networks PhD Thesis Texas A&M University, 2012. Abstract | BibTeX | Tags: forensics, mmsn, PhD thesis, thesis @phdthesis{JaiPhDThesis12, title = {Defenses Against Covert-Communications in Multimedia and Sensor Networks}, author = {Julien Sebastien Jainsky}, year = {2012}, date = {2012-12-01}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {Steganography and covert-communications represent a great and real threat today more than ever due to the evolution of modern communications. This doctoral work proposes defenses against such covert-communication techniques in two threatening but underdeveloped domains. Indeed, this work focuses on the novel problem of visual sensor network steganalysis but also proposes one of the first solutions against video steganography. The first part of the thesis looks at covert-communications in videos. The contribution of this study resides in the combination of image processing using motion vector interpolation and non-traditional detection theory to obtain better results in identifying the presence of embedded messages in videos compared to what existing still-image steganalytic solutions would offer. The proposed algorithm called MoViSteg utilizes the specifics of video, as a whole and not as a series of images, to decide on the occurrence of steganography. Contrary to other solutions, MoViSteg is a video-specific algorithm, and not a repetitive still-image steganalysis, and allows for detection of embedding in partially corrupted sequences. This thesis also lays the foundation for the novel study of visual sensor network steganalysis. We develop three different steganalytic solutions to the problem of covert communications in visual sensor networks. Because of the inadequacy of the existing steganalytic solutions present in the current research literature, we introduce the novel concept of preventative steganalysis, which aims at discouraging potential steganographic attacks. We propose a set of solutions with active and passive warden scenarii using the material made available by the network. To quantify the efficiency of the preventative steganalysis, a new measure for evaluating the risk of steganography is proposed: the embedding potential which relies on the uncertainty of the image’s pixel values prone to corruption.}, keywords = {forensics, mmsn, PhD thesis, thesis}, pubstate = {published}, tppubtype = {phdthesis} } Steganography and covert-communications represent a great and real threat today more than ever due to the evolution of modern communications. This doctoral work proposes defenses against such covert-communication techniques in two threatening but underdeveloped domains. Indeed, this work focuses on the novel problem of visual sensor network steganalysis but also proposes one of the first solutions against video steganography. The first part of the thesis looks at covert-communications in videos. The contribution of this study resides in the combination of image processing using motion vector interpolation and non-traditional detection theory to obtain better results in identifying the presence of embedded messages in videos compared to what existing still-image steganalytic solutions would offer. The proposed algorithm called MoViSteg utilizes the specifics of video, as a whole and not as a series of images, to decide on the occurrence of steganography. Contrary to other solutions, MoViSteg is a video-specific algorithm, and not a repetitive still-image steganalysis, and allows for detection of embedding in partially corrupted sequences. This thesis also lays the foundation for the novel study of visual sensor network steganalysis. We develop three different steganalytic solutions to the problem of covert communications in visual sensor networks. Because of the inadequacy of the existing steganalytic solutions present in the current research literature, we introduce the novel concept of preventative steganalysis, which aims at discouraging potential steganographic attacks. We propose a set of solutions with active and passive warden scenarii using the material made available by the network. To quantify the efficiency of the preventative steganalysis, a new measure for evaluating the risk of steganography is proposed: the embedding potential which relies on the uncertainty of the image’s pixel values prone to corruption. |
Parthasarathy, Saranya Bloom Filter Based Intrusion Detection for Smart Grid 2012. Abstract | BibTeX | Tags: MS Thesis, smart grid, thesis @masterthesis{ParMSThesis12, title = {Bloom Filter Based Intrusion Detection for Smart Grid}, author = {Saranya Parthasarathy}, year = {2012}, date = {2012-05-01}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {This thesis addresses the problem of local intrusion detection for SCADA (Supervisory Control and Data Acquisition) field devices in the smart grid. A methodology is proposed to detect anomalies in the communication patterns using a combination of n-gram analysis and Bloom Filter. The predictable and regular nature of the SCADA communication patterns is exploited to train the intrusion detection system. The protocol considered to test the proposed approach is MODBUS which is used for communication between a SCADA server and field devices in power system. The approach is tested for attacks like HMI compromise and Man-in-the-Middle. Bloom Filter is chosen because of its strong space advantage over other data structures like hash tables, linked lists etc. for representing sets. The advantage comes from its probabilistic nature and compact array structure. The false positive rates are found to be minimal with careful choice of parameters for Bloom Filter design. Also the memory-efficient property of Bloom Filter makes it suitable for implementation in resource constrained SCADA components. It is also established that the knowledge of physical state of the power system i.e., normal, emergency or restorative state can help in improving the accuracy of the proposed approach.}, keywords = {MS Thesis, smart grid, thesis}, pubstate = {published}, tppubtype = {masterthesis} } This thesis addresses the problem of local intrusion detection for SCADA (Supervisory Control and Data Acquisition) field devices in the smart grid. A methodology is proposed to detect anomalies in the communication patterns using a combination of n-gram analysis and Bloom Filter. The predictable and regular nature of the SCADA communication patterns is exploited to train the intrusion detection system. The protocol considered to test the proposed approach is MODBUS which is used for communication between a SCADA server and field devices in power system. The approach is tested for attacks like HMI compromise and Man-in-the-Middle. Bloom Filter is chosen because of its strong space advantage over other data structures like hash tables, linked lists etc. for representing sets. The advantage comes from its probabilistic nature and compact array structure. The false positive rates are found to be minimal with careful choice of parameters for Bloom Filter design. Also the memory-efficient property of Bloom Filter makes it suitable for implementation in resource constrained SCADA components. It is also established that the knowledge of physical state of the power system i.e., normal, emergency or restorative state can help in improving the accuracy of the proposed approach. |
Kollegala, Revathi S The Robust Classification of Hyperspectral Images Using Adaptive Wavelet Kernel Support Vector Data Description (AWK-SVDD) 2012. Abstract | BibTeX | Tags: fusion, MS Thesis, thesis @masterthesis{KolMSThesis12, title = {The Robust Classification of Hyperspectral Images Using Adaptive Wavelet Kernel Support Vector Data Description (AWK-SVDD)}, author = {Revathi S Kollegala}, year = {2012}, date = {2012-05-01}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {Detection of targets in hyperspectral images is a specific case of one-class classification. It is particularly relevant in the area of remote sensing and has received considerable interest in the past few years. The thesis proposes the use of wavelet functions as kernels with Support Vector Data Description for target detection in hyperspectral images. Specifically, it proposes the Adaptive Wavelet Kernel Support Vector Data Description (AWK-SVDD) that learns the optimal wavelet function to be used given the target signature. The performance and computational requirements of AWK-SVDD is compared with that of existing methods and other wavelet functions. An introduction to target detection and target detection in the context of hyperspectral images is given. This thesis also includes an overview of the thesis and lists the contributions of the thesis. A brief mathematical background into one-class classification in reference to target detection is included. Also described are the existing methods and introduces essential concepts relevant to the proposed approach. The use of wavelet functions as kernels with Support Vector Data Description, the conditions for use of wavelet functions and the use of two functions in order to form the kernel are checked and analyzed. The proposed approach, AWKSVDD, is mathematically described. The details of the implementation and the results when applied to the Urban dataset of hyperspectral images with a random target signature are given. The results confirm the better performance of AWK-SVDD compared to conventional kernels, wavelet kernels and the two-function Morlet-Radial Basis Function kernel. The problems faced with convergence during the Support Vector Data Description optimization are discussed. The thesis concludes with the suggestions for future work.}, keywords = {fusion, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } Detection of targets in hyperspectral images is a specific case of one-class classification. It is particularly relevant in the area of remote sensing and has received considerable interest in the past few years. The thesis proposes the use of wavelet functions as kernels with Support Vector Data Description for target detection in hyperspectral images. Specifically, it proposes the Adaptive Wavelet Kernel Support Vector Data Description (AWK-SVDD) that learns the optimal wavelet function to be used given the target signature. The performance and computational requirements of AWK-SVDD is compared with that of existing methods and other wavelet functions. An introduction to target detection and target detection in the context of hyperspectral images is given. This thesis also includes an overview of the thesis and lists the contributions of the thesis. A brief mathematical background into one-class classification in reference to target detection is included. Also described are the existing methods and introduces essential concepts relevant to the proposed approach. The use of wavelet functions as kernels with Support Vector Data Description, the conditions for use of wavelet functions and the use of two functions in order to form the kernel are checked and analyzed. The proposed approach, AWKSVDD, is mathematically described. The details of the implementation and the results when applied to the Urban dataset of hyperspectral images with a random target signature are given. The results confirm the better performance of AWK-SVDD compared to conventional kernels, wavelet kernels and the two-function Morlet-Radial Basis Function kernel. The problems faced with convergence during the Support Vector Data Description optimization are discussed. The thesis concludes with the suggestions for future work. |
2008 |
Okorafor, Unoma Ndili Secure Integrated Routing and Localization in Wireless Optical Sensor Networks PhD Thesis Texas A&M University, 2008. Abstract | BibTeX | Tags: mmsn, PhD thesis, thesis @phdthesis{OkoPhDThesis08, title = {Secure Integrated Routing and Localization in Wireless Optical Sensor Networks}, author = {Unoma Ndili Okorafor}, year = {2008}, date = {2008-08-31}, address = {College Station, Texas}, school = {Texas A&M University}, abstract = {Wireless ad hoc and sensor networks are envisioned to be self-organizing and autonomous networks, that may be randomly deployed where no fixed infrastructure is either feasible or cost-effective. The successful commercialization of such networks depends on the feasible implementation of network services to support security-aware applications. Recently, free space optical (FSO) communication has emerged as a viable technology for broadband distributed wireless optical sensor network (WOSN) applications. The challenge of employing FSO include its susceptibility to adverse weather conditions and the line of sight requirement between two communicating nodes. In addition, it is necessary to consider security at the initial design phase of any network and routing protocol. This dissertation addresses the feasibility of randomly deployed WOSNs employing broad beam FSO with regard to the network layer, in which two important problems are specifically investigated. First, we address the parameter assignment problem which considers the relationship amongst the physical layer parameters of node density, transmission radius and beam divergence of the FSO signal in order to yield probabilistic guarantees on network connectivity. We analyze the node isolation property of WOSNs, and its relation to the connectivity of the network. Theoretical analysis and experimental investigation were conducted to assess the effects of hierarchical clustering as well as fading due to atmospheric turbulence on connectivity, thereby demonstrating the design choices necessary to make the random deployment of the WOSN feasible. Second, we propose a novel light-weight circuit-based, secure and integrated routing and localization paradigm within the WOSN, that leverages the resources of the base station. Our scheme exploits the hierarchical cluster-based organization of the network, and the directionality of links to deliver enhanced security performance including per hop and broadcast authentication, confidentiality, integrity and freshness of routing signals. We perform security and attack analysis and synthesis to characterize the protocol’s performance, compared to existing schemes, and demonstrate its superior performance for WOSNs. Through the investigation of this dissertation, we demonstrate the fundamental tradeoff between security and connectivity in WOSNs, and illustrate how the transmission radius may be used as a high sensitivity tuning parameter to balance there two metrics of network performance. We also present WOSNs as a field of study that opens up several directions for novel research, and encompasses problems such as connectivity analysis, secure routing and localization, intrusion detection, topology control, secure data aggregation and novel attack scenarios.}, keywords = {mmsn, PhD thesis, thesis}, pubstate = {published}, tppubtype = {phdthesis} } Wireless ad hoc and sensor networks are envisioned to be self-organizing and autonomous networks, that may be randomly deployed where no fixed infrastructure is either feasible or cost-effective. The successful commercialization of such networks depends on the feasible implementation of network services to support security-aware applications. Recently, free space optical (FSO) communication has emerged as a viable technology for broadband distributed wireless optical sensor network (WOSN) applications. The challenge of employing FSO include its susceptibility to adverse weather conditions and the line of sight requirement between two communicating nodes. In addition, it is necessary to consider security at the initial design phase of any network and routing protocol. This dissertation addresses the feasibility of randomly deployed WOSNs employing broad beam FSO with regard to the network layer, in which two important problems are specifically investigated. First, we address the parameter assignment problem which considers the relationship amongst the physical layer parameters of node density, transmission radius and beam divergence of the FSO signal in order to yield probabilistic guarantees on network connectivity. We analyze the node isolation property of WOSNs, and its relation to the connectivity of the network. Theoretical analysis and experimental investigation were conducted to assess the effects of hierarchical clustering as well as fading due to atmospheric turbulence on connectivity, thereby demonstrating the design choices necessary to make the random deployment of the WOSN feasible. Second, we propose a novel light-weight circuit-based, secure and integrated routing and localization paradigm within the WOSN, that leverages the resources of the base station. Our scheme exploits the hierarchical cluster-based organization of the network, and the directionality of links to deliver enhanced security performance including per hop and broadcast authentication, confidentiality, integrity and freshness of routing signals. We perform security and attack analysis and synthesis to characterize the protocol’s performance, compared to existing schemes, and demonstrate its superior performance for WOSNs. Through the investigation of this dissertation, we demonstrate the fundamental tradeoff between security and connectivity in WOSNs, and illustrate how the transmission radius may be used as a high sensitivity tuning parameter to balance there two metrics of network performance. We also present WOSNs as a field of study that opens up several directions for novel research, and encompasses problems such as connectivity analysis, secure routing and localization, intrusion detection, topology control, secure data aggregation and novel attack scenarios. |
Luh, William Distributed Secrecy for Information Theoretic Sensor Network Models PhD Thesis Texas A&M University, 2008. Abstract | BibTeX | Tags: PhD thesis, phys-layer, thesis @phdthesis{LuhPhDThesis08, title = {Distributed Secrecy for Information Theoretic Sensor Network Models}, author = {William Luh}, year = {2008}, date = {2008-08-15}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {This dissertation presents a novel problem inspired by the characteristics of sensor networks. The basic setup through-out the dissertation is that a set of sensor nodes encipher their data without collaboration and without any prior shared secret materials. The challenge is dealt by an eavesdropper who intercepts a subset of the enciphered data and wishes to gain knowledge of the uncoded data. This problem is challenging and novel given that the eavesdropper is assumed to know everything, including secret cryptographic keys used by both the encoders and decoders. We study the above problem using information theoretic models as a necessary first step towards an understanding of the characteristics of this system problem. This dissertation contains four parts. The first part deals with noiseless channels, and the goal is for sensor nodes to both source code and encipher their data. We derive inner and outer regions of the capacity region (i.e the set of all source coding and equivocation rates) for this problem under general distortion constraints. The main conclusion in this part is that unconditional secrecy is unachievable unless the distortion is maximal, rendering the data useless. In the second part we thus provide a practical coding scheme based on distributed source coding using syndromes (DISCUS) that provides secrecy beyond the equivocation measure, i.e. secrecy on each symbol in the message. The third part deals with discrete memoryless channels, and the goal is for sensor nodes to both channel code and encipher their data. We derive inner and outer regions to the secrecy capacity region, i.e. the set of all channel coding rates that achieve (weak) unconditional secrecy. The main conclusion in this part is that interference allows (weak) unconditional secrecy to be achieved in contrast with the first part of this dissertation. The fourth part deals with wireless channels with fading and additive Gaussian noise. We derive a general outer region and an inner region based on an equal SNR assumption, and show that the two are partially tight when the maximum available user powers are admissible.}, keywords = {PhD thesis, phys-layer, thesis}, pubstate = {published}, tppubtype = {phdthesis} } This dissertation presents a novel problem inspired by the characteristics of sensor networks. The basic setup through-out the dissertation is that a set of sensor nodes encipher their data without collaboration and without any prior shared secret materials. The challenge is dealt by an eavesdropper who intercepts a subset of the enciphered data and wishes to gain knowledge of the uncoded data. This problem is challenging and novel given that the eavesdropper is assumed to know everything, including secret cryptographic keys used by both the encoders and decoders. We study the above problem using information theoretic models as a necessary first step towards an understanding of the characteristics of this system problem. This dissertation contains four parts. The first part deals with noiseless channels, and the goal is for sensor nodes to both source code and encipher their data. We derive inner and outer regions of the capacity region (i.e the set of all source coding and equivocation rates) for this problem under general distortion constraints. The main conclusion in this part is that unconditional secrecy is unachievable unless the distortion is maximal, rendering the data useless. In the second part we thus provide a practical coding scheme based on distributed source coding using syndromes (DISCUS) that provides secrecy beyond the equivocation measure, i.e. secrecy on each symbol in the message. The third part deals with discrete memoryless channels, and the goal is for sensor nodes to both channel code and encipher their data. We derive inner and outer regions to the secrecy capacity region, i.e. the set of all channel coding rates that achieve (weak) unconditional secrecy. The main conclusion in this part is that interference allows (weak) unconditional secrecy to be achieved in contrast with the first part of this dissertation. The fourth part deals with wireless channels with fading and additive Gaussian noise. We derive a general outer region and an inner region based on an equal SNR assumption, and show that the two are partially tight when the maximum available user powers are admissible. |
Czarlinska, Alexandra Stealthy Attacks and Defense Strategies in Competing Sensor Networks PhD Thesis Texas A&M University, 2008. Abstract | BibTeX | Tags: mmsn, PhD thesis, thesis @phdthesis{CzaPhDThesis08, title = {Stealthy Attacks and Defense Strategies in Competing Sensor Networks}, author = {Alexandra Czarlinska}, year = {2008}, date = {2008-08-01}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {The fundamental objective of sensor networks underpinning a variety of applications is the collection of reliable information from the surrounding environment. The correctness of the collected data is especially important in applications involving societal welfare and safety, in which the acquired information may be utilized by end-users for decision-making. The distributed nature of sensor networks and their deployment in unattended and potentially hostile environments, however, renders this collection task challenging for both scalar and visual data. In this work we propose and address the twin problem of carrying out and defending against a stealthy attack on the information gathered by a sensor network at the physical sensing layer as perpetrated by a competing hostile network. A stealthy attack in this context is an intelligent attempt to disinform a sensor network in a manner that mitigates attack discovery. In comparison with previous sensor network security studies, we explicitly model the attack scenario as an active competition between two networks where difficulties arise from the pervasive nature of the attack, the possibility of tampering during data acquisition prior to encryption, and the lack of prior knowledge regarding the characteristics of the attack We examine the problem from the perspective of both the hostile and the legitimate network. The interaction between the networks is modeled as a game where a stealth utility is derived and shown to be consistent for both players in the case of stealthy direct attacks and stealthy cross attacks. Based on the stealth utility, the optimal attack and defense strategies are obtained for each network. For the legitimate network, minimization of the attacker’s stealth results in the possibility of attack detection through established paradigms and the ability to mitigate the power of the attack. For the hostile network, maximization of the stealth utility translates into the optimal attack avoidance. This attack avoidance does not require active communication among the hostile nodes but rather relies on a level of coordination which we quantify. We demonstrate the significance and effectiveness of the solution for sensor networks acquiring scalar and multidimensional data such as surveillance sequences and relate the results to existing image sensor networks. Finally we discuss the implications of these results for achieving secure event acquisition in unattended environments.}, keywords = {mmsn, PhD thesis, thesis}, pubstate = {published}, tppubtype = {phdthesis} } The fundamental objective of sensor networks underpinning a variety of applications is the collection of reliable information from the surrounding environment. The correctness of the collected data is especially important in applications involving societal welfare and safety, in which the acquired information may be utilized by end-users for decision-making. The distributed nature of sensor networks and their deployment in unattended and potentially hostile environments, however, renders this collection task challenging for both scalar and visual data. In this work we propose and address the twin problem of carrying out and defending against a stealthy attack on the information gathered by a sensor network at the physical sensing layer as perpetrated by a competing hostile network. A stealthy attack in this context is an intelligent attempt to disinform a sensor network in a manner that mitigates attack discovery. In comparison with previous sensor network security studies, we explicitly model the attack scenario as an active competition between two networks where difficulties arise from the pervasive nature of the attack, the possibility of tampering during data acquisition prior to encryption, and the lack of prior knowledge regarding the characteristics of the attack We examine the problem from the perspective of both the hostile and the legitimate network. The interaction between the networks is modeled as a game where a stealth utility is derived and shown to be consistent for both players in the case of stealthy direct attacks and stealthy cross attacks. Based on the stealth utility, the optimal attack and defense strategies are obtained for each network. For the legitimate network, minimization of the attacker’s stealth results in the possibility of attack detection through established paradigms and the ability to mitigate the power of the attack. For the hostile network, maximization of the stealth utility translates into the optimal attack avoidance. This attack avoidance does not require active communication among the hostile nodes but rather relies on a level of coordination which we quantify. We demonstrate the significance and effectiveness of the solution for sensor networks acquiring scalar and multidimensional data such as surveillance sequences and relate the results to existing image sensor networks. Finally we discuss the implications of these results for achieving secure event acquisition in unattended environments. |
Shankar, Sonu Parameter Assignment for Improved Connectivity and Security in Randomly Deployed Wireless Sensor Networks via Hybrid Omni/Uni-Directional Antennas 2008. Abstract | BibTeX | Tags: mmsn, MS Thesis, thesis @masterthesis{ShaMSThesis08, title = {Parameter Assignment for Improved Connectivity and Security in Randomly Deployed Wireless Sensor Networks via Hybrid Omni/Uni-Directional Antennas}, author = {Sonu Shankar}, year = {2008}, date = {2008-08-01}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {Conguring a network system to operate at optimal levels of performance requires a comprehensive understanding of the effects of a variety of system parameters on crucial metrics like connectivity and resilience to network attacks. Traditionally, omni-directional antennas have been used for communication in wireless sensor networks. In this thesis, a hybrid communication model is presented where-in, nodes in a network are capable of both omni-directional and uni-directional communication. The effect of such a model on performance in randomly deployed wireless sensor networks is studied, specically looking at the effect of a variety of network parameters on network performance. The work in this thesis demonstrates that, when the hybrid communication model is employed, the probability of 100% connectivity improves by almost 90% and that of k-connectivity improves by almost 80% even at low node densities when compared to the traditional omni-directional model. In terms of network security, it was found that the hybrid approach improves network resilience to the collision attack by almost 85% and the cost of launching a successful network partition attack was increased by as high as 600%. The gains in connectivity and resilience were found to improve with increasing node densities and decreasing antenna beamwidths.}, keywords = {mmsn, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } Conguring a network system to operate at optimal levels of performance requires a comprehensive understanding of the effects of a variety of system parameters on crucial metrics like connectivity and resilience to network attacks. Traditionally, omni-directional antennas have been used for communication in wireless sensor networks. In this thesis, a hybrid communication model is presented where-in, nodes in a network are capable of both omni-directional and uni-directional communication. The effect of such a model on performance in randomly deployed wireless sensor networks is studied, specically looking at the effect of a variety of network parameters on network performance. The work in this thesis demonstrates that, when the hybrid communication model is employed, the probability of 100% connectivity improves by almost 90% and that of k-connectivity improves by almost 80% even at low node densities when compared to the traditional omni-directional model. In terms of network security, it was found that the hybrid approach improves network resilience to the collision attack by almost 85% and the cost of launching a successful network partition attack was increased by as high as 600%. The gains in connectivity and resilience were found to improve with increasing node densities and decreasing antenna beamwidths. |
Mathai, Nebu John Cybernetic Automata: An Approach for the Realization of Economical Cognition for Multi-Robot Systems PhD Thesis Texas A&M University, 2008, ((Winner of TAMU 2008 U.S. Senator Phil Gramm Doctoral Award)). Abstract | BibTeX | Tags: CPS, dyn-sys, PhD thesis, thesis @phdthesis{MatPhDThesis08, title = {Cybernetic Automata: An Approach for the Realization of Economical Cognition for Multi-Robot Systems}, author = {Nebu John Mathai}, year = {2008}, date = {2008-05-01}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {(Winner of TAMU 2008 U.S. Senator Phil Gramm Doctoral Award) The multi-agent robotics paradigm has attracted much attention due to the variety of pertinent applications that are well-served by the use of a multiplicity of agents (including space robotics, search and rescue, and mobile sensor networks). The use of this paradigm for most applications, however, demands economical, lightweight agent designs for reasons of longer operational life, lower economic cost, faster and easily-verified designs, etc. An important contributing factor to an agent’s cost is its control architecture. Due to the emergence of novel implementation technologies carrying the promise of economical implementation, we consider the development of a technology-independent specification for computational machinery. To that end, the use of cybernetics toolsets (control and dynamical systems theory) is appropriate, enabling a principled specification of robotic control architectures in mathematical terms that could be mapped directly to diverse implementation substrates. This dissertation, hence, addresses the problem of developing a technologyindependent specification for lightweight control architectures to enable robotic agents to serve in a multi-agent scheme. We present the principled design of static and dynamical regulators that elicit useful behaviors, and integrate these within an overall architecture for both single and multi-agent control. Since the use of control theory can be limited in unstructured environments, a major focus of the work is on the engineering of emergent behavior. The proposed scheme is highly decentralized, requiring only local sensing and no inter-agent communication. Beyond several simulation-based studies, we provide experimental results for a two-agent system, based on a custom implementation employing field-programmable gate arrays.}, note = {(Winner of TAMU 2008 U.S. Senator Phil Gramm Doctoral Award)}, keywords = {CPS, dyn-sys, PhD thesis, thesis}, pubstate = {published}, tppubtype = {phdthesis} } (Winner of TAMU 2008 U.S. Senator Phil Gramm Doctoral Award) The multi-agent robotics paradigm has attracted much attention due to the variety of pertinent applications that are well-served by the use of a multiplicity of agents (including space robotics, search and rescue, and mobile sensor networks). The use of this paradigm for most applications, however, demands economical, lightweight agent designs for reasons of longer operational life, lower economic cost, faster and easily-verified designs, etc. An important contributing factor to an agent’s cost is its control architecture. Due to the emergence of novel implementation technologies carrying the promise of economical implementation, we consider the development of a technology-independent specification for computational machinery. To that end, the use of cybernetics toolsets (control and dynamical systems theory) is appropriate, enabling a principled specification of robotic control architectures in mathematical terms that could be mapped directly to diverse implementation substrates. This dissertation, hence, addresses the problem of developing a technologyindependent specification for lightweight control architectures to enable robotic agents to serve in a multi-agent scheme. We present the principled design of static and dynamical regulators that elicit useful behaviors, and integrate these within an overall architecture for both single and multi-agent control. Since the use of control theory can be limited in unstructured environments, a major focus of the work is on the engineering of emergent behavior. The proposed scheme is highly decentralized, requiring only local sensing and no inter-agent communication. Beyond several simulation-based studies, we provide experimental results for a two-agent system, based on a custom implementation employing field-programmable gate arrays. |
2006 |
Chen, Anli Encrypted Media Aggregation in Wireless Sensor Networks 2006. Abstract | BibTeX | Tags: mmsn, MS Thesis, thesis @masterthesis{CheMERep08, title = {Encrypted Media Aggregation in Wireless Sensor Networks}, author = {Anli Chen}, year = {2006}, date = {2006-05-09}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {In historical investigation, sensors devices typically measure simple things such as humility, temperature, or pressure. This results in a fairly limited amount of data generated, even over thousands of sensors. Now, if we look ten years into the future when video capture devices will most likely be small and inexpensive, the ability to create video-based sensor networks will be possible. Previous literature has demonstrated the necessity of in-network data aggregation in order to minimize the volume of messages exchanged in the hierarchical wireless sensor networks. Nevertheless, with the severe power constraints, sensor networks are much more vulnerable to all those threats. A portion of the sensor devices may be physically captured by attackers, or even worse, the crucial elements like cluster heads and aggregators may also stimulate malicious intrusion. Sensor networks are more vulnerable than traditional communication and computation systems to security threats because of their severe power constraints. Furthermore, since crucial elements such as cluster heads and aggregators in sensor networks can often contain information of higher security level, they are more attractive to the attackers and may stimulate more malicious intrusion. Our primary objective is to develop a sufficiently secure, efficient, adaptive, and resilient mechanism for media aggregation within wireless sensor networks. After substantial investigation, we assert that one effective way to balance security with resource limitations for secure aggregation is to employ aggregation functions with the homomorphic attribute. This essentially means that aggregation can occur directly on ciphertext (i.e. encrypted media) opposed to plaintext (i.e. raw unencrypted data). We propose to adopt Statistical Disclosure Control (SDC), Secure Multiparty Computation (SMC) and Discrete Wavelet Transform (DWT) techniques to boost secure aggregation. We tailor the three methods into wireless sensor network scenario so that encrypted media can be securely aggregated. The result of this study allows the network administrator to adaptively select the most appropriate securing method that assures adequate protection according to their practical needs and environmental condition.}, keywords = {mmsn, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } In historical investigation, sensors devices typically measure simple things such as humility, temperature, or pressure. This results in a fairly limited amount of data generated, even over thousands of sensors. Now, if we look ten years into the future when video capture devices will most likely be small and inexpensive, the ability to create video-based sensor networks will be possible. Previous literature has demonstrated the necessity of in-network data aggregation in order to minimize the volume of messages exchanged in the hierarchical wireless sensor networks. Nevertheless, with the severe power constraints, sensor networks are much more vulnerable to all those threats. A portion of the sensor devices may be physically captured by attackers, or even worse, the crucial elements like cluster heads and aggregators may also stimulate malicious intrusion. Sensor networks are more vulnerable than traditional communication and computation systems to security threats because of their severe power constraints. Furthermore, since crucial elements such as cluster heads and aggregators in sensor networks can often contain information of higher security level, they are more attractive to the attackers and may stimulate more malicious intrusion. Our primary objective is to develop a sufficiently secure, efficient, adaptive, and resilient mechanism for media aggregation within wireless sensor networks. After substantial investigation, we assert that one effective way to balance security with resource limitations for secure aggregation is to employ aggregation functions with the homomorphic attribute. This essentially means that aggregation can occur directly on ciphertext (i.e. encrypted media) opposed to plaintext (i.e. raw unencrypted data). We propose to adopt Statistical Disclosure Control (SDC), Secure Multiparty Computation (SMC) and Discrete Wavelet Transform (DWT) techniques to boost secure aggregation. We tailor the three methods into wireless sensor network scenario so that encrypted media can be securely aggregated. The result of this study allows the network administrator to adaptively select the most appropriate securing method that assures adequate protection according to their practical needs and environmental condition. |
Fei, Chuhong Analysis and Design of Watermark-Based Multimedia Authentication Systems PhD Thesis University of Toronto, 2006. Abstract | BibTeX | Tags: drm, PhD thesis, thesis @phdthesis{FeiPhDThesis08, title = {Analysis and Design of Watermark-Based Multimedia Authentication Systems}, author = {Chuhong Fei}, year = {2006}, date = {2006-01-01}, address = {Toronto, Canada}, school = {University of Toronto}, abstract = {Multimedia authentication techniques are required to protect the integrity and origin of digital multimedia data. In watermark-based multimedia authentication systems, a source-dependent authenticator is invisibly embedded within the protected data itself, in order to alert unacceptable distortions on the data and to authenticate the legitimate source. This thesis investigates the design and analysis of such systems. We formulate the authentication problem as error detection coding with robustness to certain types of legitimate channel noise. System performance requirements such as semi-fragility, security, key payload, embedding distortion, and algorithm complexity are all investigated in the unified framework to obtain best tradeoffs among them.In the analysis of multimedia authentication systems, we demonstrate how lattice codes can be used to address semi-fragile requirements and embedding distortion in a practical scheme. Security against possible malicious attacks is considered at the code level, and cryptographic techniques are incorporated to construct secure codes. We propose a novel security enhancement strategy based on nested lattice codes that results in secure and efficient authentication algorithms. Unconditional security is also investigated. We provide a formal methodology using composite hypothesis testing to balance robustness and fragility objectives with respect to legitimate and illegitimate distortions that is superior to existing approaches. We show that a quantization-based watermarking scheme is more appropriate for achieving semi-fragility.In system design, we propose two practical watermark-based authentication schemes for natural images: one for uncompressed images, the other for JPEG compressed ones. Our proposed algorithms are able to distinguish incidental distortions, such as JPEG compression and image enhancement filtering, from malicious tampering such as image object removal and substitution even in a small portion of the protected images. Our algorithms are secure against an active attacker, and are able to determine the degree of distortion and its location. In addition, our proposed joint compression and authentication scheme for compressed images is able to increase compression efficiency while keeping practical robustness to mild incidental signal processing changes. Effectiveness of the proposed algorithms is demonstrated by simulations and comparison with existing schemes. In the analysis of multimedia authentication systems, we demonstrate how lattice codes can be used to address semi-fragile requirements and embedding distortion in a practical scheme. Security against possible malicious attacks is considered at the code level, and cryptographic techniques are incorporated to construct secure codes. We propose a novel security enhancement strategy based on nested lattice codes that results in secure and efficient authentication algorithms. Unconditional security is also investigated. We provide a formal methodology using composite hypothesis testing to balance robustness and fragility objectives with respect to legitimate and illegitimate distortions that is superior to existing approaches. We show that a quantization-based watermarking scheme is more appropriate for achieving semi-fragility. In system design, we propose two practical watermark-based authentication schemes for natural images: one for uncompressed images, the other for JPEG compressed ones. Our proposed algorithms are able to distinguish incidental distortions, such as JPEG compression and image enhancement filtering, from malicious tampering such as image object removal and substitution even in a small portion of the protected images. Our algorithms are secure against an active attacker, and are able to determine the degree of distortion and its location. In addition, our proposed joint compression and authentication scheme for compressed images is able to increase compression efficiency while keeping practical robustness to mild incidental signal processing changes. Effectiveness of the proposed algorithms is demonstrated by simulations and comparison with existing schemes.}, keywords = {drm, PhD thesis, thesis}, pubstate = {published}, tppubtype = {phdthesis} } Multimedia authentication techniques are required to protect the integrity and origin of digital multimedia data. In watermark-based multimedia authentication systems, a source-dependent authenticator is invisibly embedded within the protected data itself, in order to alert unacceptable distortions on the data and to authenticate the legitimate source. This thesis investigates the design and analysis of such systems. We formulate the authentication problem as error detection coding with robustness to certain types of legitimate channel noise. System performance requirements such as semi-fragility, security, key payload, embedding distortion, and algorithm complexity are all investigated in the unified framework to obtain best tradeoffs among them.In the analysis of multimedia authentication systems, we demonstrate how lattice codes can be used to address semi-fragile requirements and embedding distortion in a practical scheme. Security against possible malicious attacks is considered at the code level, and cryptographic techniques are incorporated to construct secure codes. We propose a novel security enhancement strategy based on nested lattice codes that results in secure and efficient authentication algorithms. Unconditional security is also investigated. We provide a formal methodology using composite hypothesis testing to balance robustness and fragility objectives with respect to legitimate and illegitimate distortions that is superior to existing approaches. We show that a quantization-based watermarking scheme is more appropriate for achieving semi-fragility.In system design, we propose two practical watermark-based authentication schemes for natural images: one for uncompressed images, the other for JPEG compressed ones. Our proposed algorithms are able to distinguish incidental distortions, such as JPEG compression and image enhancement filtering, from malicious tampering such as image object removal and substitution even in a small portion of the protected images. Our algorithms are secure against an active attacker, and are able to determine the degree of distortion and its location. In addition, our proposed joint compression and authentication scheme for compressed images is able to increase compression efficiency while keeping practical robustness to mild incidental signal processing changes. Effectiveness of the proposed algorithms is demonstrated by simulations and comparison with existing schemes. In the analysis of multimedia authentication systems, we demonstrate how lattice codes can be used to address semi-fragile requirements and embedding distortion in a practical scheme. Security against possible malicious attacks is considered at the code level, and cryptographic techniques are incorporated to construct secure codes. We propose a novel security enhancement strategy based on nested lattice codes that results in secure and efficient authentication algorithms. Unconditional security is also investigated. We provide a formal methodology using composite hypothesis testing to balance robustness and fragility objectives with respect to legitimate and illegitimate distortions that is superior to existing approaches. We show that a quantization-based watermarking scheme is more appropriate for achieving semi-fragility. In system design, we propose two practical watermark-based authentication schemes for natural images: one for uncompressed images, the other for JPEG compressed ones. Our proposed algorithms are able to distinguish incidental distortions, such as JPEG compression and image enhancement filtering, from malicious tampering such as image object removal and substitution even in a small portion of the protected images. Our algorithms are secure against an active attacker, and are able to determine the degree of distortion and its location. In addition, our proposed joint compression and authentication scheme for compressed images is able to increase compression efficiency while keeping practical robustness to mild incidental signal processing changes. Effectiveness of the proposed algorithms is demonstrated by simulations and comparison with existing schemes. |
2005 |
Budhia, Udit Steganalysis of Video Sequences using Collusion Sensitivity 2005. Abstract | BibTeX | Tags: forensics, MS Thesis, thesis @masterthesis{BudMSThesis05, title = {Steganalysis of Video Sequences using Collusion Sensitivity}, author = {Udit Budhia}, year = {2005}, date = {2005-05-01}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {In this thesis we present an effective steganalysis technique for digital video sequences based on the collusion attack. Steganalysis is the process of detecting with a high probability the presence of covert data in multimedia. Existing algorithms for steganalysis target detecting covert information in still images. When applied directly to video sequences these approaches are suboptimal. In this thesis we present methods that overcome this limitation by using redundant information present in the temporal domain to detect covert messages in the form of Gaussian watermarks. In particular we target the spread spectrum steganography method because of its widespread use. Our gains are achieved by exploiting the collusion attack that has recently been studied in the field of digital video watermarking and more sophisticated pattern recognition tools. Through analysis and simulations we, evaluate the effectiveness of the video steganalysis method based on averaging based collusion scheme. Other forms of collusion attack in the form of weighted linear collusion and block-based collusion schemes have been proposed to improve the detection performance. The proposed steganalsyis methods were successful in detecting hidden watermarks bearing low SNR with high accuracy. The simulation results also show the improved performance of the proposed temporal based methods over the spatial methods. We conclude that the essence of future video steganalysis techniques lies in the exploitation of the temporal redundancy.}, keywords = {forensics, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } In this thesis we present an effective steganalysis technique for digital video sequences based on the collusion attack. Steganalysis is the process of detecting with a high probability the presence of covert data in multimedia. Existing algorithms for steganalysis target detecting covert information in still images. When applied directly to video sequences these approaches are suboptimal. In this thesis we present methods that overcome this limitation by using redundant information present in the temporal domain to detect covert messages in the form of Gaussian watermarks. In particular we target the spread spectrum steganography method because of its widespread use. Our gains are achieved by exploiting the collusion attack that has recently been studied in the field of digital video watermarking and more sophisticated pattern recognition tools. Through analysis and simulations we, evaluate the effectiveness of the video steganalysis method based on averaging based collusion scheme. Other forms of collusion attack in the form of weighted linear collusion and block-based collusion schemes have been proposed to improve the detection performance. The proposed steganalsyis methods were successful in detecting hidden watermarks bearing low SNR with high accuracy. The simulation results also show the improved performance of the proposed temporal based methods over the spatial methods. We conclude that the essence of future video steganalysis techniques lies in the exploitation of the temporal redundancy. |
2004 |
Luh, William Collusion-Resistant Fingerprinting for Multimedia in a Broadcast Channel Environment 2004. Abstract | BibTeX | Tags: drm, MS Thesis, thesis @masterthesis{LuhMSThesis04, title = {Collusion-Resistant Fingerprinting for Multimedia in a Broadcast Channel Environment}, author = {William Luh}, year = {2004}, date = {2004-12-01}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {Digital fingerprinting is a method by which a copyright owner can uniquely embed a buyer-dependent, inconspicuous serial number (representing the fingerprint) into every copy of digital data that is legally sold. The buyer of a legal copy is then deterred from distributing further copies, because the unique fingerprint can be used to trace back the origin of the piracy. The major challenge in fingerprinting is collusion, an attack in which a coalition of pirates compare several of their uniquely fingerprinted copies for the purpose of detecting and removing the fingerprints. The contributions of this thesis are two-fold. First, this thesis motivates the need for robustness against large coalitions of pirates by introducing the concept of a malicious distributor that has been overlooked in prior work. A novel fingerprinting code that has superior codeword length in comparison to existing work under this novel malicious distributor scenario, is developed. In addition, ideas presented in the proposed ¯ngerprinting design can easily be applied to existing fingerprinting schemes, making them more robust to collusion attacks. Second, a new framework termed Joint Source Fingerprinting that integrates the processes of watermarking and codebook design is introduced. The need for this new paradigm is motivated by the fact that existing ¯ngerprinting methods result in a perceptually undistorted multimedia after collusion is applied. In contrast, the new paradigm equates the process of collusion amongst a coalition of pirates, to degrading the perceptual characteristics, and hence commercial value of the multimedia in ques- tion. Thus by enforcing that the process of collusion diminishes the commercial value of the content, the pirates are deterred from attacking the ¯ngerprints. A ¯ngerprint- ing algorithm for video as well as an e±cient means of broadcasting or distributing ¯ngerprinted video is also presented. Simulation results are provided to verify our theoretical and empirical observations.}, keywords = {drm, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } Digital fingerprinting is a method by which a copyright owner can uniquely embed a buyer-dependent, inconspicuous serial number (representing the fingerprint) into every copy of digital data that is legally sold. The buyer of a legal copy is then deterred from distributing further copies, because the unique fingerprint can be used to trace back the origin of the piracy. The major challenge in fingerprinting is collusion, an attack in which a coalition of pirates compare several of their uniquely fingerprinted copies for the purpose of detecting and removing the fingerprints. The contributions of this thesis are two-fold. First, this thesis motivates the need for robustness against large coalitions of pirates by introducing the concept of a malicious distributor that has been overlooked in prior work. A novel fingerprinting code that has superior codeword length in comparison to existing work under this novel malicious distributor scenario, is developed. In addition, ideas presented in the proposed ¯ngerprinting design can easily be applied to existing fingerprinting schemes, making them more robust to collusion attacks. Second, a new framework termed Joint Source Fingerprinting that integrates the processes of watermarking and codebook design is introduced. The need for this new paradigm is motivated by the fact that existing ¯ngerprinting methods result in a perceptually undistorted multimedia after collusion is applied. In contrast, the new paradigm equates the process of collusion amongst a coalition of pirates, to degrading the perceptual characteristics, and hence commercial value of the multimedia in ques- tion. Thus by enforcing that the process of collusion diminishes the commercial value of the content, the pirates are deterred from attacking the ¯ngerprints. A ¯ngerprint- ing algorithm for video as well as an e±cient means of broadcasting or distributing ¯ngerprinted video is also presented. Simulation results are provided to verify our theoretical and empirical observations. |
Dube, Raghav Denial of Service Attacks: Path Reconstruction for IP Traceback using Adjusted Probabilistic Packet Marking 2004. Abstract | BibTeX | Tags: forensics, MS Thesis, thesis @masterthesis{DubMSThesis04, title = {Denial of Service Attacks: Path Reconstruction for IP Traceback using Adjusted Probabilistic Packet Marking}, author = {Raghav Dube}, year = {2004}, date = {2004-12-01}, address = {College Station, TX}, school = {Texas A&M University}, abstract = {The use of Internet has revolutionized the way information is exchanged, changed business paradigms and put mission critical and sensitive systems online. Any disruption of this connectivity and the plethora of services provided results in significant damages to everyone involved. Denial of Service (DoS) attacks are becoming increasingly common and are the cause of lost time and revenue. Flooding type DoS attacks use spoofed IP addresses to disguise the attackers. This makes identification of the attackers extremely difficult. This work proposes a new scheme that allows the victim of a DoS attack to identify the correct origin of the malicious traffic. The suggested mechanism requires routers to mark packets using adjusted probabilistic marking. This results in a lower number of packet-markings required to identify the traffic source. Unlike many related works, we use the existing IPv4 header structure to incorporate these markings. We simulate and test our algorithms using real Internet trace data to show that our technique is fast, and works successfully for a large number of distributed attackers.}, keywords = {forensics, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } The use of Internet has revolutionized the way information is exchanged, changed business paradigms and put mission critical and sensitive systems online. Any disruption of this connectivity and the plethora of services provided results in significant damages to everyone involved. Denial of Service (DoS) attacks are becoming increasingly common and are the cause of lost time and revenue. Flooding type DoS attacks use spoofed IP addresses to disguise the attackers. This makes identification of the attackers extremely difficult. This work proposes a new scheme that allows the victim of a DoS attack to identify the correct origin of the malicious traffic. The suggested mechanism requires routers to mark packets using adjusted probabilistic marking. This results in a lower number of packet-markings required to identify the traffic source. Unlike many related works, we use the existing IPv4 header structure to incorporate these markings. We simulate and test our algorithms using real Internet trace data to show that our technique is fast, and works successfully for a large number of distributed attackers. |
Mathai, Nebu John 0.18 CMOS Implementation of a Video Watermarking Algorithm 2004. Abstract | BibTeX | Tags: drm, MS Thesis, thesis @masterthesis{MatMSThesis04, title = {0.18 CMOS Implementation of a Video Watermarking Algorithm}, author = {Nebu John Mathai}, year = {2004}, date = {2004-12-01}, address = {Toronto, Canada}, school = {University of Toronto}, abstract = {We consider hardware implementation aspects of the digital watermarking problem through the implementation of a well-known video watermarking algorithm called Just Another Watermarking System (JAWS); we discuss the time and area constraints that must be satisfied by a successful hardware implementation. A hardware architecture that implements the algorithm under the constraints is then proposed. The architecture is analyzed to gain an understanding of the relationships between algorithmic features and implementation cost. Some general findings of this work that can be applied toward making algorithmic developments more amenable to hardware implementation are finally presented.}, keywords = {drm, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } We consider hardware implementation aspects of the digital watermarking problem through the implementation of a well-known video watermarking algorithm called Just Another Watermarking System (JAWS); we discuss the time and area constraints that must be satisfied by a successful hardware implementation. A hardware architecture that implements the algorithm under the constraints is then proposed. The architecture is analyzed to gain an understanding of the relationships between algorithmic features and implementation cost. Some general findings of this work that can be applied toward making algorithmic developments more amenable to hardware implementation are finally presented. |
2003 |
Zhao, Yang Dual Domain Semi-Fragile Watermarking for Image Authentication 2003. Abstract | BibTeX | Tags: drm, forensics, MS Thesis, thesis @masterthesis{ZhaMSThesis03, title = {Dual Domain Semi-Fragile Watermarking for Image Authentication}, author = {Yang Zhao}, year = {2003}, date = {2003-12-01}, address = {Toronto, Canada}, school = {University of Toronto}, abstract = {Techniques to establish the authenticity and integrity of digital images are becoming increasingly essential for secure transacting. Ideally, the authentication algorithm should distinguish incidental integrity maintaining distortions such as lossy compression from malicious manipulations. This has motivated research into semi-ragile watermarking. A novel watermarking algorithm is proposed in this thesis that is both robust to compression and self-authenticating. The proposed algorithm is a content-based, semi-fragile watermarking method that employs a public-key scheme for still image authentication and integrity veri¯cation. The use of dual domains in the proposed algorithm enables greater control over the robustness and fragility of the overall scheme to manipulations, and provides very good classi¯cation of intentional and incidental tampering. In addition, the thesis provides theoretical analysis for the performance and the feasibility of the scheme. We also present experimental results to verify the theoretical observations and the comparison results for the proposed algorithm to four popular techniques.}, keywords = {drm, forensics, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } Techniques to establish the authenticity and integrity of digital images are becoming increasingly essential for secure transacting. Ideally, the authentication algorithm should distinguish incidental integrity maintaining distortions such as lossy compression from malicious manipulations. This has motivated research into semi-ragile watermarking. A novel watermarking algorithm is proposed in this thesis that is both robust to compression and self-authenticating. The proposed algorithm is a content-based, semi-fragile watermarking method that employs a public-key scheme for still image authentication and integrity veri¯cation. The use of dual domains in the proposed algorithm enables greater control over the robustness and fragility of the overall scheme to manipulations, and provides very good classi¯cation of intentional and incidental tampering. In addition, the thesis provides theoretical analysis for the performance and the feasibility of the scheme. We also present experimental results to verify the theoretical observations and the comparison results for the proposed algorithm to four popular techniques. |
Squeira, Adrian Enhanced Watermark Detection 2003. Abstract | BibTeX | Tags: drm, MS Thesis, thesis @masterthesis{SeqMSThesis03, title = {Enhanced Watermark Detection}, author = {Adrian Squeira}, year = {2003}, date = {2003-12-01}, address = {Toronto, Canada}, school = {University of Toronto}, abstract = {Digital watermarking is a relatively overhead free solution to the problem of copyright infringement. In this thesis we investigate the choice of transform domain for embedding blind and non-blind watermarks in the face of eight different attacks. The chosen attacks are commonly used in watermark benchmarking programs. After extensive simulations involving seventeen different transforms, we find that our findings corroborate the results obtained by Ramkumar et al. for compression attacks. In addition, we analyse the Voloshynovskiy scheme for its probability of false alarm in a novel way. We then use the transform domain chosen from above and introduce the use of the SAGE algorithm as a parameter estimator. This algorithm is used to lower the probability of false alarm for the Voloshynovskiy scheme by improving the accuracy of parameter estimation and therefore lowering the variance of the detector output.}, keywords = {drm, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } Digital watermarking is a relatively overhead free solution to the problem of copyright infringement. In this thesis we investigate the choice of transform domain for embedding blind and non-blind watermarks in the face of eight different attacks. The chosen attacks are commonly used in watermark benchmarking programs. After extensive simulations involving seventeen different transforms, we find that our findings corroborate the results obtained by Ramkumar et al. for compression attacks. In addition, we analyse the Voloshynovskiy scheme for its probability of false alarm in a novel way. We then use the transform domain chosen from above and introduce the use of the SAGE algorithm as a parameter estimator. This algorithm is used to lower the probability of false alarm for the Voloshynovskiy scheme by improving the accuracy of parameter estimation and therefore lowering the variance of the detector output. |
2002 |
Ahsan, Kamran Covert Channel Analysis and Data Hiding in TCP/IP 2002. Abstract | BibTeX | Tags: forensics, MS Thesis, thesis @masterthesis{AhsMAScThesis02, title = {Covert Channel Analysis and Data Hiding in TCP/IP}, author = {Kamran Ahsan}, year = {2002}, date = {2002-08-01}, abstract = {This thesis investigates the existence of covert channels in computer networks by analyzing the transport and the Internet layers of the TCP/IP protocol suite. Two approaches for data hiding are identified: packet header manipulation and packet sorting. Each scenario facilitates the interaction of steganographic principles with the existing network security environment. Specifically, we show how associating additional information with IPv4 headers can ease up security mechanisms in network nodes like routers, firewalls and for services such as authentication, audit, and billing. Furthermore, use of packet sorting with the IP Sec framework results in an enhanced network security architecture. The packet sorting approach is simulated at the network layer which provides a feasibility of packet sorting under varying network conditions. While bridging the areas of data hiding, network protocols and network security, both techniques have potential for practical data hiding at the transport and network layers.}, keywords = {forensics, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } This thesis investigates the existence of covert channels in computer networks by analyzing the transport and the Internet layers of the TCP/IP protocol suite. Two approaches for data hiding are identified: packet header manipulation and packet sorting. Each scenario facilitates the interaction of steganographic principles with the existing network security environment. Specifically, we show how associating additional information with IPv4 headers can ease up security mechanisms in network nodes like routers, firewalls and for services such as authentication, audit, and billing. Furthermore, use of packet sorting with the IP Sec framework results in an enhanced network security architecture. The packet sorting approach is simulated at the network layer which provides a feasibility of packet sorting under varying network conditions. While bridging the areas of data hiding, network protocols and network security, both techniques have potential for practical data hiding at the transport and network layers. |
2001 |
Su, Karen Digital Video Watermarking Principles for Resistance to Collusion and Interpolation Attacks 2001. Abstract | BibTeX | Tags: drm, MS Thesis, thesis @masterthesis{SuMAScThesis01, title = {Digital Video Watermarking Principles for Resistance to Collusion and Interpolation Attacks}, author = {Karen Su}, year = {2001}, date = {2001-09-01}, address = {Toronto, Canada}, school = {University of Toronto}, abstract = {In this thesis,w e propose two video watermarks based on the novel ideas of statistical invisibility and content-synchronized placement. We present a mathematical framework designed to facilitate collusion analysis and thereby enable protection from this important class of attacks. We define statistical invisibility and show that it is not only a property that supports the desired resistance to such attacks,but that it can also be easily induced using a spatially localized image-dependent approach. To construct the watermark,the notion of a watermark’s footprint,the spatial locations over which its energy is spread,is introduced. By defining localized footprints with regular structures,e.g.,sets of subframes within each frame, current image watermarks can immediately be applied at the subframe level. Results are presented to demonstrate the effectiveness of the algorithms. Comparisons are made with the well-known JAWS and CDMA video watermarks,as well as the StirMark 3.1 benchmarking suite.}, keywords = {drm, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } In this thesis,w e propose two video watermarks based on the novel ideas of statistical invisibility and content-synchronized placement. We present a mathematical framework designed to facilitate collusion analysis and thereby enable protection from this important class of attacks. We define statistical invisibility and show that it is not only a property that supports the desired resistance to such attacks,but that it can also be easily induced using a spatially localized image-dependent approach. To construct the watermark,the notion of a watermark’s footprint,the spatial locations over which its energy is spread,is introduced. By defining localized footprints with regular structures,e.g.,sets of subframes within each frame, current image watermarks can immediately be applied at the subframe level. Results are presented to demonstrate the effectiveness of the algorithms. Comparisons are made with the well-known JAWS and CDMA video watermarks,as well as the StirMark 3.1 benchmarking suite. |
Fei, Chuhong The Choice of Transform for Robust Watermarking in the Presence of Lossy Compression 2001. Abstract | BibTeX | Tags: drm, MS Thesis, thesis @masterthesis{FeiMAScThesis01, title = {The Choice of Transform for Robust Watermarking in the Presence of Lossy Compression}, author = {Chuhong Fei}, year = {2001}, date = {2001-04-01}, address = {Toronto, Canada}, school = {University of Toronto}, abstract = {Digital watermarking technology is an approach for the protection of digital information against illegal duplication and manipulation. In this thesis, we concentrate on the problem of robust watermarking in the presence of lossy compression. We investigate how the embedding of the watermark signal in a suitable transform domain can improve performance. Two typical classes of watermarking techniques are considered: one is the spread spectrum watermarking method, the other is the quantization based watermarking method. Based on a communication paradigm for watermarking, we present and information-theoretic approach to estimate the number of watermark bits that can be reliably hidden. The best domain for watermarking is determined to maximize the watermark channel capacity. Based on the advantages and disadvantages of both watermarking methods, a novel hybrid watermarking technique is proposed which combines the best of both spread spectrum and quantization based methods.}, keywords = {drm, MS Thesis, thesis}, pubstate = {published}, tppubtype = {masterthesis} } Digital watermarking technology is an approach for the protection of digital information against illegal duplication and manipulation. In this thesis, we concentrate on the problem of robust watermarking in the presence of lossy compression. We investigate how the embedding of the watermark signal in a suitable transform domain can improve performance. Two typical classes of watermarking techniques are considered: one is the spread spectrum watermarking method, the other is the quantization based watermarking method. Based on a communication paradigm for watermarking, we present and information-theoretic approach to estimate the number of watermark bits that can be reliably hidden. The best domain for watermarking is determined to maximize the watermark channel capacity. Based on the advantages and disadvantages of both watermarking methods, a novel hybrid watermarking technique is proposed which combines the best of both spread spectrum and quantization based methods. |