Browsing by Author "Santhi Thilagam, P."

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A broker based approach for cloud provider selection
(Institute of Electrical and Electronics Engineers Inc., 2014) Achar, R.; Santhi Thilagam, P.
Rapid growth of internet technology made many IaaS providers arise across the globe to meet the needs of small IT companies. Number of IT companies started using resources of IaaS provider due to elastic and pay as you go nature. Increasing number of cloud providers results in difficulty for requester to select suitable cloud provider based on requirements. In this paper we present a broker based architecture for selecting suitable cloud provider from multiple providers. The broker measure the quality of each cloud provider and prioritize them based on the needs of the requester. The experiment is conducted using cloudsim simulator shows that proposed architecture selects suitable cloud provider. Â© 2014 IEEE.
A Probabilistic Model of Clock Offset Estimator (PMCOE) for Clock Synchronization in Wireless Sensor Network
(Springer New York LLC barbara.b.bertram@gsk.com, 2019) Upadhyay, D.; Dubey, A.K.; Santhi Thilagam, P.
Synchronization of clock within a wireless sensor network epitomizes crucial problems in the efficient and reliable operation of the sensors. This paper discusses a novel probability theory based clock offset estimator for various clock synchronization schemes of wireless sensor networks is proposed. The motivation is to utilize local clock timing for achieving the global clock synchronization. It presents a probabilistic model to estimate the most expected value of clock offset for sensor nodes. This model uses a statistical tools based on dispersion and central tendency. The proposed model was compared with the existing clock offset estimating models. It was observed that the proposed model gives better results with 1.008% accuracy, 0.065% precision and 99.8% efficiency. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.
An abstraction based communication efficient distributed association rule mining
(2008) Santhi Thilagam, P.; Ananthanarayana, V.S.
Association rule mining is one of the most researched areas because of its applicability in various fields. We propose a novel data structure called Sequence Pattern Count, SPC, tree which stores the database compactly and completely and requires only one scan of the database for its construction. The completeness property of the SPC tree with respect to the database makes it more suitable for mining association rules in the context of changing data and changing supports without rebuilding the tree. A performance study shows that SPC tree is efficient and scalable. We also propose a Doubly Logaxithmic-depth Tree, DLT, algorithm which uses SPC tree to efficiently mine the huge amounts of geographically distributed datasets in order to minimize the communication and computation costs. DLT requires only O(n) messages for support count exchange and it takes only O(log log n) time for exchange of messages, which increases its efficiency. � Springer-Verlag Berlin Heidelberg 2008.
Alleviating data sparsity and cold start in recommender systems using social behaviour
(2016) Reshma, R.; Ambikesh, G.; Santhi Thilagam, P.
Recommender systems are used to find preferences of people or to predict the ratings with the help of information available from other users. The most widely used collaborative filtering recommender system by the e-commerce sites suffers from both the sparsity and cold-start problem due to insufficient data. Most of the existing systems consider only the ratings of the similar users and they do not give any preferences to the social behavior of users which shall aid the recommendations made to the user to a great extent. In this paper, instead of finding similarity from rating information, we propose a new approach which predicts the ratings of items by considering directed and transitive trust with timestamps and profile similarity from the social network along with the user-rated information. In cases where the trust and the rating details of users from the system is absent, we still make use of the social data of the users like the products liked by the user, user's social profile-education status, location etc.To make recommendation. Experimental analysis proves that our approach can improve the user recommendations at the extreme levels of sparsity in user-rating data. We also show that our approach works considerably well for cold-start users under the circumstances where collaborative filtering approach fails. � 2016 IEEE.
An empirical study of license violations in open source projects
(2012) Mathur, A.; Choudhary, H.; Vashist, P.; Thies, W.; Santhi Thilagam, P.
The use of Open Source Software (OSS) components in building applications has presented the challenge of integrating them in a way such that the licenses of the individual components do not conflict with each other and if applicable, the overall license of the application. These conflicts lead to violations, with many having far reaching legal consequences. While proprietary software firms are often plagued with the risks of not satisfying the clauses of OSS licenses, we hypothesize that a large degree of code reuse within the OSS community poses similar threats too. Through an analysis of 1423 projects, consisting of approximately 69 million non-blank lines of code from Google Code project hosting, we validate instances of code reuse between projects by comparing their licenses. Our results discover four violations, evaluated by searching for files that share similar content. Additionally, we present statistics on code reuse within the set of projects. Â© 2013 IEEE.
Approaches and challenges of privacy preserving search over encrypted data
(2019) Siva Kumar D.V.N.; Santhi Thilagam, P.
More and more data owners are encouraged to outsource their data onto cloud servers for reducing infrastructure, maintenance cost and also to get ubiquitous access to their stored data. However, security is one issue that discourages data owners from adopting cloud servers for data storage. Searchable Encryption (SE) is one of the few ways of assuring privacy and confidentiality of such data by storing them in encrypted form at the cloud servers. SE enables the data owners and users to search over encrypted data through trapdoors. Most of the user information requirements are fulfilled either through Boolean or Ranked search approaches. This paper aims at understanding how the confidentiality and privacy of information can be guaranteed while processing single and multi-keyword queries over encrypted data using Boolean and Ranked search approaches. This paper presents all possible leakages that happen in SE and also specifies which privacy preserving approach to be adopted in SE schemes to prevent those leakages to help the practitioners and researchers to design and implement secure searchable encryption systems. It also highlights various application scenarios where SE could be utilized. This paper also explores the research challenges and open problems that need to be focused in future. © 2018 Elsevier Ltd
Approaches and challenges of privacy preserving search over encrypted data
(Elsevier Ltd, 2019) Siva Kumar, D.V.N.; Santhi Thilagam, P.
More and more data owners are encouraged to outsource their data onto cloud servers for reducing infrastructure, maintenance cost and also to get ubiquitous access to their stored data. However, security is one issue that discourages data owners from adopting cloud servers for data storage. Searchable Encryption (SE) is one of the few ways of assuring privacy and confidentiality of such data by storing them in encrypted form at the cloud servers. SE enables the data owners and users to search over encrypted data through trapdoors. Most of the user information requirements are fulfilled either through Boolean or Ranked search approaches. This paper aims at understanding how the confidentiality and privacy of information can be guaranteed while processing single and multi-keyword queries over encrypted data using Boolean and Ranked search approaches. This paper presents all possible leakages that happen in SE and also specifies which privacy preserving approach to be adopted in SE schemes to prevent those leakages to help the practitioners and researchers to design and implement secure searchable encryption systems. It also highlights various application scenarios where SE could be utilized. This paper also explores the research challenges and open problems that need to be focused in future. © 2018 Elsevier Ltd
A broker based approach for cloud provider selection
(2014) Achar, R.; Santhi Thilagam, P.
Rapid growth of internet technology made many IaaS providers arise across the globe to meet the needs of small IT companies. Number of IT companies started using resources of IaaS provider due to elastic and pay as you go nature. Increasing number of cloud providers results in difficulty for requester to select suitable cloud provider based on requirements. In this paper we present a broker based architecture for selecting suitable cloud provider from multiple providers. The broker measure the quality of each cloud provider and prioritize them based on the needs of the requester. The experiment is conducted using cloudsim simulator shows that proposed architecture selects suitable cloud provider. � 2014 IEEE.
Broker-based mechanism for cloud provider selection
(Inderscience Publishers, 2020) Achar, R.; Santhi Thilagam, P.; Acharya, S.
Cloud computing has recently emerged as a new computing paradigm for delivering on demand virtualised computing resources over the internet on a pay-as-use basis. Applications hosted in cloud have different requirements which include both low level (resource) requirements and high level (performance) requirements. However, most of the cloud providers satisfy SLAs based on resource requirements rather than providing performance guarantees to applications. This gap creates a need for selecting a more suitable cloud provider who can satisfy performance requirements of applications along with resource requirements. This work aims at proposing a broker-based approach to rank cloud providers based on QoS requirements of customers. It helps the SaaS providers to save cost and complexity in choosing a suitable cloud provider for hosting applications. The experimental results show that proposed approach selects the suitable cloud provider for hosting various types of applications satisfying the needs of different cloud customers. Â© 2020 Inderscience Enterprises Ltd.
Crime base: Towards building a knowledge base for crime entities and their relationships from online news papers
(Elsevier Ltd, 2019) Srinivasa, S.; Santhi Thilagam, P.
In the current era of internet, information related to crime is scattered across many sources namely news media, social networks, blogs, and video repositories, etc. Crime reports published in online newspapers are often considered as reliable compared to crowdsourced data like social media and contain crime information not only in the form of unstructured text but also in the form of images. Given the volume and availability of crime-related information present in online newspapers, gathering and integrating crime entities from multiple modalities and representing them as a knowledge base in machine-readable form will be useful for any law enforcement agencies to analyze and prevent criminal activities. Extant research works to generate the crime knowledge base, does not address extraction of all non-redundant entities from text and image data present in multiple newspapers. Hence, this work proposes Crime Base, an entity relationship based system to extract and integrate crime related text and image data from online newspapers with a focus towards reducing duplicity and loss of information in the knowledge base. The proposed system uses a rule-based approach to extract the entities from text and image captions. The entities extracted from text data are correlated using contextual as-well-as semantic similarity measures and image entities are correlated using low-level and high-level image features. The proposed system also presents an integrated view of these entities and their relations in the form of a knowledge base using OWL. The system is tested for a collection of crime related articles from popular Indian online newspapers. © 2019 Elsevier Ltd
Cross-layer IDS for rushing attack in wireless mesh networks
(2012) Ganesh, Reddy, K.; Santhi Thilagam, P.; Rao, B.N.
Wireless Mesh Networks (WMNs) are a promising technology to provide the wireless internet connectivity. WMNs are becoming a popular choice for wireless internet service providers to offer internet connectivity as it allows a fast, easy and inexpensive network deployment. However, security in WMNs is still in its infancy. Security and privacy has been a major concern in WMNs. WMNs are susceptible to broad variety of attacks due to its open medium, dynamic topology and lack of physical security. WMNs are more vulnerable in Network layer. Several attacks are possible in the network layer. Some of the attacks have possible solutions but there is no solution for to detect Rushing attack which leads to the Denial of Service. In this paper, the authors proposed Cross- Layer Intrusion Detection System (CLIDS) for Rushing attack. We evaluated the performance of our technique using network simulator 2. Simulation results show that CLIDS has less false positive and false negative rates than single layer intrusion detection system. Copyright � 2012 ACM.
Cross-layer IDS for rushing attack in wireless mesh networks
(2012) Karri, K.; Santhi Thilagam, P.; Rao, B.N.
Wireless Mesh Networks (WMNs) are a promising technology to provide the wireless internet connectivity. WMNs are becoming a popular choice for wireless internet service providers to offer internet connectivity as it allows a fast, easy and inexpensive network deployment. However, security in WMNs is still in its infancy. Security and privacy has been a major concern in WMNs. WMNs are susceptible to broad variety of attacks due to its open medium, dynamic topology and lack of physical security. WMNs are more vulnerable in Network layer. Several attacks are possible in the network layer. Some of the attacks have possible solutions but there is no solution for to detect Rushing attack which leads to the Denial of Service. In this paper, the authors proposed Cross- Layer Intrusion Detection System (CLIDS) for Rushing attack. We evaluated the performance of our technique using network simulator 2. Simulation results show that CLIDS has less false positive and false negative rates than single layer intrusion detection system. Copyright Â© 2012 ACM.
DDoS attacks at the application layer: Challenges and research perspectives for safeguarding web applications
(2019) Praseed A.; Santhi Thilagam, P.
Distributed denial of service (DDoS) attacks are some of the most devastating attacks against Web applications. A large number of these attacks aim to exhaust the network bandwidth of the server, and are called network layer DDoS attacks. They are volumetric attacks and rely on a large volume of network layer packets to throttle the bandwidth. However, as time passed, network infrastructure became more robust and defenses against network layer attacks also became more advanced. Recently, DDoS attacks have started targeting the application layer. Unlike network layer attacks, these attacks can be carried out with a relatively low attack volume. They also utilize legitimate application layer requests, which makes it difficult for existing defense mechanisms to detect them. These attacks target a wide variety of resources at the application layer and can bring a server down much faster, and with much more stealth, than network layer DDoS attacks. Over the past decade, research on application layer DDoS attacks has focused on a few classes of these attacks. This paper attempts to explore the entire spectrum of application layer DDoS attacks using critical features that aid in understanding how these attacks can be executed. defense mechanisms against the different classes of attacks are also discussed with special emphasis on the features that aid in the detection of different classes of attacks. Such a discussion is expected to help researchers understand why a particular group of features are useful in detecting a particular class of attacks. © 2018 IEEE.
Deriving temporal trends in user preferences through short message strings
(2016) Deb, S.; Mohan, S.; Venkatraman, P.; Bindu, P.V.; Santhi Thilagam, P.
Short message strings are widely prevalent in the age of social networking. Taking Facebook as an example, a user may have many other users in his contact list. However, at any given time frame, the user interacts with only a small subset of these users. In this paper, we propose a recommender system that determines which users have common interests based on the content of the short message strings of different users. The system calculates the similarity between two users based on the contents of short message strings by the users over a certain time period. A similarity measure based on short message strings must be temporal study as the contents of the short messages vary rapidly over time. Experimental study is conducted in the Facebook domain using status updates of users. � 2016 IEEE.
Detection of XML signature wrapping attack using node counting
(2016) Gupta, A.N.; Santhi Thilagam, P.
In context of web service security, several standards are defined to secure exchanges of SOAP messages in web service environment. Prominent among these security standards is the digital signature. SOAP messages are signed partially or fully before being transmitted. But recent researches has shown that even signed messages are vulnerable to interception and manipulation of content. We refer to these types of attacks as XML signature wrapping attacks. In this paper, an approach is proposed to detect the XML signature wrapping attacks on signed web service requests using node counting. We detect XML signature wrapping attacks by calculating the frequency of each node in web service request. Experiments show that the proposed solution is computationally less expensive and has better performance in securing the exchange of SOAP messages. � Springer International Publishing Switzerland 2016.
Detection of XML signature wrapping attack using node counting
(Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2016) Gupta, A.N.; Santhi Thilagam, P.
In context of web service security, several standards are defined to secure exchanges of SOAP messages in web service environment. Prominent among these security standards is the digital signature. SOAP messages are signed partially or fully before being transmitted. But recent researches has shown that even signed messages are vulnerable to interception and manipulation of content. We refer to these types of attacks as XML signature wrapping attacks. In this paper, an approach is proposed to detect the XML signature wrapping attacks on signed web service requests using node counting. We detect XML signature wrapping attacks by calculating the frequency of each node in web service request. Experiments show that the proposed solution is computationally less expensive and has better performance in securing the exchange of SOAP messages. Â© Springer International Publishing Switzerland 2016.
Diffusion models and approaches for influence maximization in social networks
(2016) Tejaswi, V.; Bindu, P.V.; Santhi Thilagam, P.
Social Network Analysis (SNA) deals with studying the structure, relationship and other attributes of social networks, and provides solutions to real world problems. Influence maximization is one of the significant areas in SNA as it helps in finding influential entities in online social networks which can be used in marketing, election campaigns, outbreak detection, and so on. It deals with the problem of finding a subset of nodes called seeds such that it will eventually spread maximum influence in the network. This paper focuses on providing a complete survey on the influence maximization problem and covers three major aspects: i) different types of input required ii) influence propagation models that map the spread of influence in the network, and iii) the approximation algorithms suggested for seed set selection. We also provide the state of the art and describe the open problems in this domain. � 2016 IEEE.
DYNA-RANK: Efficient calculation and updation of pagerank
(2008) Kale, M.; Santhi Thilagam, P.
The decision of the ranking of web page is very important in web, as its growing and changing very rapidly. Ranking of the results in a search engine for a query plays crucial role for huge database like Web, where one query can have millions of results. The browsing nature of web will mostly depend on the ranking of the search results. The existing approaches for calculating pagerank values are mostly centralized and the ones which are distributed, are not being used for practical purposes because of the scalability reasons. The centralized approaches considers total web as one graph and they calculate the pagerank values of total graph after certain time period, which takes long execution time and can be in days. In the same way updating the graph also compels to recalculate all the pagerank values of all the pages in the graph. This suggests possible applicability of the distributed algorithm to pagerank computations as a replacement for the centralized pagerank calculation algorithm. Considering the importance of the "Ranking" in searching context, our approach DYNA-RANK, focuses upon efficiently calculating and updating Google's pagerank vector using "peer to peer" system. The changes in the web structure will be handled incrementally amongst the peers. DYNA-RANK produces the relative pagerank on each peer. DYNA-RANK is proven to take less computation time and less number of iterations compared to centralized approach. � 2008 IEEE.
Dynamic resource allocation for multi-tier applications in cloud
(2016) Achar, R.; Santhi Thilagam, P.; Meghana; Niha, Fathima, Haris, B.; Bhat, H.; Ekta, K.
Increasing demand for computing resources and widespread adaption of service-oriented architecture has made cloud as a new IT delivery mechanism. Number of cloud providers offer computing resources in the form of virtual machines to the cloud customers based on business requirements. Load experienced by the present business applications hosted in cloud are dynamic in nature. This creates a need for a mechanism which allocates resources dynamically to the applications in order to minimize performance degradations. This paper presents a mechanism which dynamically allocates the resources based on load of the application using vertical and horizontal scaling. Cloud environment is set up using Xen cloud platform and multi-tier web application is deployed on virtual machines. Experimental study conducted for various loads show that proposed mechanism ensures the response time is within the acceptable range. � Springer Science+Business Media Singapore 2016.
Dynamic resource allocation for multi-tier applications in cloud
(Springer Verlag service@springer.de, 2016) Achar, R.; Santhi Thilagam, P.; Meghana; Niha Fathima Haris, B.; Bhat, H.; Ekta, K.
Increasing demand for computing resources and widespread adaption of service-oriented architecture has made cloud as a new IT delivery mechanism. Number of cloud providers offer computing resources in the form of virtual machines to the cloud customers based on business requirements. Load experienced by the present business applications hosted in cloud are dynamic in nature. This creates a need for a mechanism which allocates resources dynamically to the applications in order to minimize performance degradations. This paper presents a mechanism which dynamically allocates the resources based on load of the application using vertical and horizontal scaling. Cloud environment is set up using Xen cloud platform and multi-tier web application is deployed on virtual machines. Experimental study conducted for various loads show that proposed mechanism ensures the response time is within the acceptable range. Â© Springer Science+Business Media Singapore 2016.