Abstract

The World Wide Web has evolved from a set of simple static pages connected by hyper links to a complex platform, to meet the demands of users and businesses. The modern web is characterised by complex operations such as online social networking, content sharing, electronic payments, single sign-on etc. The evolution of web APIs (Application Programming Interfaces) and open data initiatives encouraged developers to build Mashups, web applications that integrate data from multiple servers. Data has become the currency on the web, due to which the web has turned into a lucrative target for attackers a.k.a cyber criminals. Newer web standards such as HTML5 are evolving and newer versions of browsers are emerging to meet the needs of the modern web. However, the security policies governing the web have not evolved at the same pace. Due to this, the number of vulnerabilities and newer web based attacks are increasing rapidly. Browsers, being the entry points to the web, are heavily targeted by attackers. One good reason is that the time and effort required to compromise a website due to a vulnerability in the application layer is much lesser compared to that of other layers. E.g., to steal certain sensitive data from a web server, it is much easier to inject a small snippet of JavaScript into a vulnerable web page loaded in a browser and exfiltrate the data, than to intercept a connection and break a fairly strong crypto system, or to bypass firewalls and break into the network. This work attempts to understand the core security policies of web browsers that govern the security and privacy of web interactions. It closely examines a series of client side web attacks, their existing defenses and deficiencies. It observes the need for novel application-level security frameworks as well as browser security policies in mitigating them. The outcome of the work is two fold: Firstly, it presents a security abstraction layer (as an API library) called “SafeMash”, which helps developers build safe mashups over the current low-level security APIs in HTML5. Secondly and more importantly, it proposes a novel declarative browser security policy called CORP (Cross Origin Request Policy) to mitigate a set of attacks which we refer to as “Web Infiltration attacks”. CORP enables a server to control which site can access which resource on a cross-origin server, and through which browser event. To evaluate the effectiveness of SafeMash and CORP, several experiments were conducted. The usage of SafeMash was empirically demonstrated by first building an interactive mashup using open APIs from ProgrammableWeb (without using state-of-the-art security echanisms) and then rebuilding it using SafeMash without losing functionality. To clearly understand the security model of web browsers and its limitations, a corpus of web attacks was developed. The formulation, effectiveness and ease of deployment of CORP was demonstrated based on the insights derived from examining the corpus of web attacks. The design of CORP was formally verified by building a light weight model in the Alloy model finder. An implementation of CORP was provided as a browser extension for Chrome and it is evaluated against real-world cross origin attacks on open source web applications. Our initial investigation revealed that most of the popular websites already segregate their resources in a way which makes deployment of CORP easier.

Abstract

The field of quantum information and computing has gained a lot of attention in the past couple of decades. It is an inter-disciplinary field comprising of mathematics, physics and computer science. Researchers have been able to exploit the quantum properties like superposition and entanglement to improve the efficiency of classical algorithms and communication and cryptographic protocols. In this thesis, we address a few problems in quantum cryptography and communications. We introduce the basic mathematical structures and postulates of quantum theory in the first chapter. We also describe the basic quantum information tools which are essential of this thesis. The field of quantum cryptography is introduced here as well.In the second chapter, we address a problem in quantum secret sharing schemes. We give a protocol for sequential quantum secret sharing where the dealer does not have access to all the secrets at the beginning of the protocol. We also show that the resource requirement for our protocol is optimal. We analyze our protocol in case of a noisy quantum channel. We use weak measurements to demonstrate that the efficiency of the protocol in such noisy environments can be enhanced. In the third chapter. we address a problem in a new emerging sub field of quantum cryptography, namely, device independent cryptography. We discuss the issues of the usual quantum cryptographic schemes and show how device independent cryptography addresses some of those issues. In particular, we deal with the case when Alice and Bob has been provided with untrusted devices and Eve can control Bob’s detectors using tailored bright pulses. We analyze the security of such attacks in a semi-device independent scenario and give the sufficient conditions for unconditional security. In the final chapter, we introduce an useful information processing task, namely broadcasting of correlations. It essentially deals with the procedures of creating a larger number of less correlated systems from a highly correlated system. Then we move on to broadcasting of general correlations (possibly even stronger than quantum correlations). We introduce the the mathematical framework and define linear transformation rules. We study the correlation properties of the resulting resources in terms of the initial correlations and transformation parameter.

Abstract

This thesis describes a system for EnergyPlus speedup that splits a single annual EnergyPlus simulation into 12 simulations, runs them in parallel over a cluster of 12 computers, collates the results once the simulations are finished, and does a quality analysis (of the parallelization) on the results. This thesis is based on the earlier studies done on the methodology for speeding EnergyPlus simulation by splitting an annual EnergyPlus simulation into multiple smaller simulations. The EPparallel tool, developed as a part of this thesis, uses Message Passing Interface API and runs on Linux. The thesis describes the methodology to prepare the input file for multiple runs, how the computers are connected to form the cluster, how message passing & file sharing is done between the nodes, and how the results generated by multiple instances of EnergyPlus are collated. Further, a quality check method has been developed which gives indication on the level of accuracy the parallel runs have achieved as compared to the results that would have been obtained by a single annual run. Also, an enhancement has been made on shadow synchronization technique proposed in the earlier studies. The tool has been tested on 16 different commercial reference buildings over 16 US weather files (total 256 combinations). The results of these 256 runs, showing the runtimes, overheads, speed gains, and accuracy of results are presented in this thesis. The speed gain ranged from 2.9x to 7.8x and accuracy (percentage of output values obtained in parallel simulation which were off by more than 1% as compared to output values obtained in annual simulation) ranged from 0% to 3.7%.

Abstract

E-contracts are textual documents describing various contractual assignments/tasksand dependencies among contractual elements such as parties, activities, clauses, exceptions and payments. The dependencies and constraints in e-contract can be differently stated in different parts of large documents. Inconsistencies in the e-contract document, particularly the contract activities and clauses specification, may lead to failures during contract enactment. The thesis work focuses on (i) ensuring consistency at specification level, (ii) failure detection through consistency checking and their handling at execution levelduring e-contract enactmentand(iii) failure preventionby assessing the possible failuresthat may arise due to inconsistent task specifications (leads to violation of constraints during execution) and thereby avoid from abnormal termination of workflow execution.To determine the consistency of an e-contract document, we construct two graphs namelySentence Dependency Graphand Contract Element Dependency Graphfrom dependencies existing in the contract document. We also develop a methodology usingthese two graphs for consistency detection in an e-contract. We also present an evaluation of our approach on a sample contract document and come up with visualization for showing dependencies of contract elements which are present in the document contract. Since contracts may evolve over a period of time, an e-contract enactment system should adapt to changing requirements. For this purpose, we use the concept of Meta Execution Workflowsfor e-contract enactment. Meta execution workflows allow modification of the workflow execution engine process to support design and run time changes. In this thesis, we present a framework to execute workflows in a seamless manner by handling exceptions and failures, and thereby ensuring consistency during e-contract execution. Our framework, using meta execution engine, representsthe workflow execution engine and other components of WFMSin terms of workflows. Our system allows specification, instantiation, modification and execution of workflows on-the-fly with less human intervention even when failures occur.We also provide design and implementation aspects of Failure Resilient Workflow System (FRWS)and demonstrate its applicability for different failure scenarios of anexample e-contract.Though the proposed solution is specific to e-contract enactment, it can be made generic and applied to other domains where the business processes are modeled using workflows.

Abstract

Humans perceive speech as made up of sequence of discrete sounds. However to represent speech as a sequence of phones with well defined, non-overlapping intervals is a challenging problem. This is because of the continuously varying vocal tract system (i.e., vocal tract configuration and vocal fold vibration) leading to the co-articulation effect, where the current phone is considerably influenced by its adjacent phones. Despite this co-articulation effect, there exists events called landmarks, occurring due to abrupt variations in the vocal tract system. Detection of these landmarks can be used to represent speech as a sequence of phones which may help in building systems that process speech similar to that of humans. Landmarks are the time instants in the acoustic signal that are consistently correlated to major artic- ulatory movements such as transition of the vocal tract from a more open to a more closed configuration and vice-versa (i.e., change in manner of articulation), and transition from a free vibration to complete cessation of vocal fold vibration and vice-versa. These landmarks are foci and hence processing of speech can be done only around landmarks instead of considering the entire speech signal, thus reduc- ing the amount of processing required. Also, the analysis around different landmarks can be done with different resolutions. Landmark detection is hierarchical and hence more than one evidence can be ob- tained for making decisions. In this thesis, the hierarchy that exists among landmarks is exploited for vowel landmark detection (VLD). Sonorant segmentation is performed first, and then vowel landmarks are detected in the sonorant regions. Sonorant refers to the sound that is produced with no sufficiently strong constriction so as to produce turbulent noise or stoppage of airflow. The broad manner classes like vowels, nasals and approxi- mants are categorized under sonorants, whereas fricatives, stops and non-speech regions are considered as non-sonorants. Sonorant segmentation of speech signals is critical in developing automatic speech recognition (ASR) systems, audio search systems and for automatic segmentation of speech corpora. In this work, acoustic features based on excitation source and vocal tract system characteristics of sono- rant sounds are proposed for segmentation of sonorant regions in continuous speech. The features are based on energy of zero frequency resonator signal, strength of excitation and dominant resonance fre- quency around epochs. An algorithm is developed to relate these features in a hierarchical manner using knowledge-based approach. Performance of the proposed algorithm is studied on three different datasets, for varying levels of degradation. Vowels being a subclass of sonorant sounds, they exhibit characteristics similar to sonorants. So the features used for sonorant segmentation of speech are also considered for detection of vowel landmarks. Apart from these, features which capture characteristics specific to vowels are also considered for the task of vowel landmark detection (VLD). Using these features, a rule-based algorithm is developed for VLD. Performance of the proposed VLD algorithm is studied on three different databases namely, TIMIT (read), NTIMIT (channel degraded) and Switchboard corpus (conversational speech). The pro- posed algorithm is also tested on TIMIT and NTIMIT datasets for different levels of noise degradations. Speech-laugh is a speech-synchronous form of laughter that often occurs in natural conversation. Speech-laugh not only signifies the emotional state of a speaker, but also carry the linguistic informa- tion. Traditional automatic speech recognition (ASR) systems consider both laughter and speech-laugh as paralinguistic elements. This resulted in loss of information. Discriminating speech-laughs from laughter improves the accuracy of ASR systems. It also helps to know the emotion expressed by laughter i.e., happy, sarcasm etc. In this work, as an application of VLD, excitation source features extracted only in the vowel regions are analyzed for discriminating speech-laugh from laughter and neutral speech

Abstract

Computing a maximal independent set (MIS) is a fundamental problem in distributed computing for its ability to nicely capture the essential challenge of symmetry breaking and also for its myriad applications to other problems. A relaxed version of computing an MIS is the problem of computing a t-ruling set. A t-ruling set for an integer t ≥ 1 in a graph G is an independent subset S ⊆ V such that every nodes v ∈ V is either in S or has a neighbor w ∈ S at a distance at most t from v. Computing a t-ruling set also involves symmetry breaking. All the algorithms we present in this thesis are randomized and synhronous in nature. First, we √ log ∆ O( log log n) rounds with + e present an algorithm which computes a 2-ruling set in any graph in log log n high probability, where n denotes the number of vertices in the graph and ∆ denotes the maximum log ∆ 1/2+ degree of any vertex in the graph. This result is an improvement over the O (log n) + (log n) √ round algorithm from [6] whenever ∆ ∈ O(2 log n ). We then use it to present another algorithm which √ can compute a 2-ruling set for graphs of arboricity a = 2 O( log n) in O( (log n/ log log n) rounds with high probability. We then extend the ideas from the above algorithm and show that a (t + 1)-ruling set for any t ≥ 1 in graphs with arboricity a = O(log log n) can be computed in O(t log 1/t ∆ + t 2 (log log n) 1/t + (log log n) 2 ) rounds. Therefore, a log log ∆-ruling set for bounded arboricity graphs can be computed in O((log log n) 2 ) rounds. Our results therefore indicate that while computing an MIS in graphs of √ bounded arboricity in O( log n) rounds is still an open problem, ruling sets for small values of t can be found in much fewer rounds. Similarly, a (t + 1)-ruling set for a general graph can be computed in √ O(t log 1/t ∆ + t 2 (log log n) 1/t + e O( log log n) ) rounds. Also, a t-ruling set for graphs of girth > 6 can √ be computed in O(t log 1/t ∆ + t 2 (log log n) 1/t + e O( log log n) ) rounds. In a later section, we compare the run time of Luby’s [13] and M ́etivier’s [14] MIS algorithms, two fundamental algorithms for computing an MIS in general graphs. Also, we try to understand the effect of probability of a node getting selected by Luby’s algorithm on the number of rounds required by algorithm to finish. We run these algorithms on different types of graphs, namely Random, Regular and Bipartite Graphs.

Abstract

Today, large amount of audio data is available on the web in the form of audiobooks, podcasts, video lectures, video blogs, news bulletins. In addition, we can effortlessly record and store audio data such as read/lecture/impromptu speech on hand-held devices. These data are rich in prosody, provide a plethora of voices to choose from, and their availability can significantly reduce the overhead of data preparation involved in building general purpose synthesizers, thus helping to rapidly building synthetic voices. But, a few problems such as the following are associated with readily using this data for speech synthesis (1) these audio files are generally long and audio-transcriptions alignment is memory intensive (2) available corresponding transcriptions are approximate, (3) many times no transcriptions are available at all, (4) the audio may contain disfluencies and non-speech noises, since the audio is not specifically recorded for building synthetic voices, and (5) if we obtain automatic transcripts, they are not error free. Earlier works on long audio alignment which addressed the first and second issue generally preferred reasonable transcripts, and mainly focused on (1) less manual intervention, (2) mispronunciation detection and (3) segmentation error recovery. In this thesis, we used a public domain large vocabulary automatic speech recognition (ASR) system to obtain transcripts, followed by confidence measure based data pruning which together address the five issues with the found data, and also ensure the above three points. For proof of concept, we built voices in English language using audiobook (read speech) in female voice downloaded from Librivox and lecture (spontaneous speech) in male voice downloaded from Coursera using both reference and hypotheses transcriptions, and evaluated them in terms of intelligibility and naturalness with the help of perceptual listening test on Blizzard 2013 corpus. The results of subjective intelligibility and naturalness test show that we can build voices of quality comparable to those built using reference transcriptions with the use of automatic transcripts and confidence measure based data pruning.

Abstract

The data rates have seen a phenomenal increase from 2G with 9.6 kbps per time slot to LTE-Advanced with 1Gbps. It is more than a thousand fold increase. Even this huge data rate is not going to cater the needs of present day era of smart phones and tablets. Wireless Internet has exploded to 100 petabytes of data transfer per day. This clearly suggests that the capacity of the wireless networks has to be increased many fold, failing which will cause an internet slow down. Heterogeneous networks (HetNets) are an attractive means of expanding mobile network capacity. A heterogeneous network (HetNets) is typically composed of multiple radio access technologies, architectures, transmission solutions, and base stations of varying transmission power. Combining such a variety of technologies together enables the best option to be chosen for a given area, but it also presents problems in terms of ubiquity and operation with such a variation of technologies and approaches. Nevertheless, mobile operators are looking to adopt the heterogeneous cellular network, HetNets approach to enable them to meet their goals for coverage and capacity as much greater demands are placed on mobile networks In this thesis, the main objective is to increase the capacity of the wireless networks by enhancing the performance of HetNets from three different directions: Resource Allocation, Interference Mitigation and employing the latest techniques such as beam forming. Channel is the most important resource in wireless networks more so in the case of HetNets as it contains the combination of many different wireless technologies. Although Channel Allocation is a widely studied problem in literature, there is still a scope of improvement when it comes to the latest HetNets technology. In this work, Predictive modeling technique such as regression model is used for effective utilization of the channels by the means of proper allocation. Interference Mitigation in HetNets is a very complicated problem because of the heterogeneous nature. Femtocells. Pico cells, Wifi, Macrocells, all these different technologies have to coexist in one area which creates huge interference challenges to each other. In this work, we proposed intelligent power adaptive strategy and beam control strategies to mitigate the interference in highly dense femto cell deployment scenario.

Abstract

A Workflow is a collection of coordinated tasks designed to carry out a well-defined process. Work flows are ubiquitous in process management. The question we address in this thesis is how to specify and design verifiable work flows for such processes. To specify work flows, we borrow a simple algebraic notation from computer science. We illustrate the use of two algebraic specification languages: Pi-calculus and Calculus of Communicating Systems (CCS), through a series of typical work flow examples. We explore two areas of application for workflows: Education and E-governance. Building such systems remains a challenge: on the one hand, the systems are required to be open, whereas, on the other, there is the need to preserve and protect private and confidential information of potentially millions of users. This requires that systems carry clear specifications of how access to users’ documents are managed throughout an application’s work flow. We describe a modular, fine-grained, state-based model that can form the basis for specifying access control in e-governance service delivery workflows. The model consists of three layers: a data store, a workflow layer, and an access control layer. The data store consists of fields and forms. The work flow is specified as concurrent processes each representing a user. The access control layer specifies, for each user (process), the user’s view of the data store as determined by that user’s state in the work flow. Such modular specifications can guide the implementation and the verification of e-governance applications.We give a web-based prototype implementation for the model and show an example of an application generated by the implementation. This implementation differentiates access control from the workflow engine. However, we also show how access control can be modelled using Pi-calculus.

Abstract

Robots tend to fail very frequently in games like Soccer. Due to either collision with other players or objects, or extreme body actions or accident, or wear and tear of robot parts, the robot might either become unstable and even fail in the worst case. Also in soccer, fouls happen and players are sent off most commonly resulting in the variation of the number of players active in the game. The temporary or permanent unavailability of a robot player due to these situations disturbs the strategy of the team which in turn impacts the outcome of the game since the team strategy plays a key role in taking major decisions like formations of the robots, roles and actions assignment to robots to achieve the final target - win the game. So, it is essential for the game strategy of a soccer team to dynamically handle fail and fouls of the robots during the game. Whenever there are failures of the robots in the team, the remaining robots need to quickly analyze the state of the game, restrategize and come up with a new set of actions for the team. The aim of this thesis is to propose an elementary failure resilient strategy for an 11 robots vs. 11 robots soccer team that works towards scoring the goals considering the failure of the robots. Our strategy is elementary because it is based on the idea of redistributing the work among surviving robots to either defend or attack. This study has two major parts:(1) Investigation of different game strategies that are already implemented in vogue, (2) from the observation of these strategies, design a game strategy for an 11vs11 Robot Soccer Team that can effectively handle the fail and fouls of the robots during the game. Four different strategies each focusing on different perspectives of the game are taken and simulated for observation and analysis. In the failure resilient strategy, decisions on player’s formation, roles and actions are made dynamically considering the state of the robots (active or failed) to achieve the common objective of defending the goal line and scoring a goal. The strategy is designed in such a way that it is not affected by the dynamic change in the number of robots due to failure during the game. In this thesis, mechanisms followed to implement the four basic independent actions of the robot player necessary to play the game are also discussed.