Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
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Item 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 LtdItem Reputation-based cross-layer intrusion detection system for wormhole attacks in wireless mesh networks(John Wiley and Sons Inc 410 Park Avenue, 15th Floor, 287 pmb New York NY 10022, 2014) Karri, G.R.; Santhi Thilagam, P.Wireless mesh networks provide long-distance wireless network connectivity over heterogeneous devices for greater scalability and availability. However, protecting legitimate long-distance wireless links from wormhole attacks is an important yet challenging security issue in wireless mesh networks. In this paper, we propose a reputation-based cross-layer intrusion detection system to effectively detect various wormhole attacks. The proposed system analyses the behaviours of the routing paths in wireless mesh networks to correctly isolate the malicious wormhole paths from legitimate long-distance wireless links. It uses reputation and cross-layer parameters for comprehensive ability to isolate the wormhole attacks in routing paths. This isolation ensures full utilisation of legitimate long-distance wireless links in wireless mesh networks, which is not possible with the existing wormhole attack detection approaches. Experimental results show that the proposed system increases the detection rate, decreases the false alarm rate, and secures legitimate long-distance wireless links in wireless mesh networks. © 2014 John Wiley & Sons, Ltd.Item Optimization of countour based template matching using GPGPU based hexagonal framework(Machine Intelligence Research (MIR) Labs contact@mirlabs.org, 2015) Bhagya, M.; Tripathi, S.; Santhi Thilagam, P.This paper presents a technique to optimize contour based template matching by using general purpose computation on graphics processing units (GPGPU). Contour based template matching requires edge detection and searching for presence of a template in an entire image, real time implementation of which is not trivial. Using the proposed solution, we could achieve an implementation fast enough to process a standard video (640x480) in real time with sufficient accuracy.Item Heuristics based server consolidation with residual resource defragmentation in cloud data centers(Elsevier, 2015) Sunil Rao, K.; Santhi Thilagam, P.Server Consolidation is one of the foremost concerns associated with the effective management of a Cloud Data Center as it has the potential to accomplish significant reduction in the overall cost and energy consumption. Most of the existing works on Server Consolidation have focused only on reducing the number of active physical servers (PMs) using Virtual Machine (VM) Live Migration. But, along with reducing the number of active PMs, if a consolidation approach reduces residual resource fragmentation, the residual resources can be efficiently used for new VM allocations, or VM reallocations, and some future migrations can also be reduced. None of the existing works have explicitly focused on reducing residual resource fragmentation along with reducing the number of active PMs to the best of our knowledge. We propose RFAware Server Consolidation, a heuristics based server consolidation approach which performs residual resource defragmentation along with reducing the number of active PMs in cloud data centers. © 2014 Elsevier B.V. All rights reserved.Item 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.Item 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 LtdItem Searchable encryption approaches: attacks and challenges(Springer London, 2019) Siva Kumar, D.V.N.; Santhi Thilagam, P.Searchable encryption (SE) is a cryptographic technique that allows the users to perform search over outsourced encrypted data in cloud servers while preserving the privacy of data and search query. In order to preserve privacy and security, data owners use various encryption schemes to encrypt their data and indexes. Due to the vulnerabilities in the encryption schemes adopted by SE schemes, information leakages are possible from the encrypted data. The cloud servers use various information disclosure attacks that exploit these leakages to infer plaintext information. In this paper, we analyze the existing SE approaches with respect to their security and precision goals and possible attacks on them. We also identify the root causes of these attacks and their remedies. An experimental study is also performed to investigate the susceptibility of SE schemes against attacks and countermeasures to prevent them. © 2018, Springer-Verlag London Ltd., part of Springer Nature.Item Multiplexed Asymmetric Attacks: Next-Generation DDoS on HTTP/2 Servers(Institute of Electrical and Electronics Engineers Inc., 2020) Praseed, A.; Santhi Thilagam, P.Distributed Denial of Service (DDoS) attacks using the HTTP protocol have started gaining popularity in recent years. A recent trend in this direction has been the use of computationally expensive requests to launch attacks. These attacks, called Asymmetric Workload attacks can bring down servers using limited resources, and are extremely difficult to detect. The introduction of HTTP/2 has been welcomed by developers because it improves user experience and efficiency. This was made possible by the ability to transport HTTP requests and their associated inline resources simultaneously by using Multiplexing and Server Push. However multiplexing has made request traffic bursty and rendered DDoS detection mechanisms based on connection limiting obsolete. Contrary to its intention, multiplexing can also be misused to launch sophisticated DDoS attacks using multiple high workload requests in a single TCP connection. However, sufficient research has not been done in this area. Existing research demonstrates that the HTTP/2 protocol allows users to launch DDoS attacks easily, but does not focus on whether an HTTP/2 server can handle DDoS attacks more efficiently or not. Also, sufficient research has not been done on the possibility of Multiplexing and Server Push being misused. In this work, we analyse the performance of an HTTP/2 server compared to an HTTP/1.1 server under an Asymmetric DDoS attack for the same load. We propose a new DDoS attack vector called a Multiplexed Asymmetric DDoS attack, which uses multiplexing in a different way than intended. We show that such an attack can bring down a server with just a few attacking clients. We also show that a Multiplexed Asymmetric Attack on a server with Server Push enabled can trigger an egress network layer flood in addition to an application layer attack. © 2005-2012 IEEE.Item Naïve bayes classifier to mitigate the DDoS attacks severity in Ad-Hoc networks(Kohat University of Science and Technology ijcnis@gmail.com, 2020) Karri, K.; Santhi Thilagam, P.Ad-Hoc networks are becoming more popular due to their unique characteristics. As there is no centralized control, these networks are more vulnerable to various attacks, out of which Distributed Denial of Service (DDoS) attacks consider as more severe attacks. DDoS attack detection and mitigation is still a challenging issue in Ad-Hoc Networks. The existing solutions find the fixed or dynamic threshold value to detect the DDoS attacks without any trained data. Very few existing solutions use machine learning algorithms to detect these attacks. However, existing solutions are inefficient to handle when DDoS attackers perform this attack through bursty traffic, packet size, and fake packets flooding. We have proposed DDoS attack severity mitigation solution. Out DDoS mitigation solution consists of a new network node authentication module and naïve Bayes classifier module to detect and isolate the DDoS attack traffic patterns. Our simulation results show that naïve Bayes DDoS attack traffic classification outperforms in the hostile environment and secure the legitimate traffic from DDoS attack. © 2020, Kohat University of Science and Technology.Item Next-Generation DDoS Attacks on IoT Deployments: Targeting the Advanced Features of MQTT v5.0 Protocol(Institute of Electrical and Electronics Engineers Inc., 2025) Lakshminarayana, S.; Santhi Thilagam, P.Message queuing telemetry transport (MQTT) has emerged as the widely adopted application layer protocol for IoT environments because of its lightweight header, minimal power, and bandwidth requirements. Despite its popularity, the earlier version of the protocol, MQTT v3.1.1, encounters performance issues in large-scale implementations and required an update to handle the growing requirements of modern IoT applications. In response to these concerns, MQTT v5.0 was released with several significant features designed to enhance the reliability, user experience, and performance of IoT systems. While the MQTT protocol features were intended to facilitate robust and efficient communications, adversaries could exploit these features to mount various types of attacks in IoT deployments. More specifically, the Denial-of-Service (DoS) attacks toward the MQTT protocol have recently gained a lot of attention from the research community. However, the existing works primarily focus only on exploring the possibilities of misusing the MQTT v3.1.1 protocol features to generate DoS attacks in IoT realms. In this work, we attempt to extensively investigate the advanced protocol features of MQTT v5.0 that can be exploited to launch DDoS attacks impacting the IoT paradigm. We present the first critical evaluation of Distributed DoS (DDoS) attacks on the MQTT v5.0 protocol by analyzing three significant features: 1) CONNECT properties; 2) user properties; and 3) flow control. Moreover, we systematically propose attack scenarios based on the adversary’s capabilities, thus illustrating the practicality of proposed attacks in real-world scenarios. Furthermore, we built a real-world testbed for IoT healthcare application to evaluate the severity of the identified attacks. The experimental results demonstrate the effectiveness of these attacks in impacting the availability of guaranteed IoT services to legitimate users, even in times of need. Additionally, we disclose the insightful findings of this work as takeaways and present research initiatives toward developing effective defense mechanisms for MQTT v5.0 protocol. We hope that such a discussion could pave the way for future research, contributing to MQTT v5.0 security and resiliency. © 2014 IEEE.