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Elliptic curve cryptography (ECC) is a remarkable mathematical tool that offers the same level of security as traditional public-key cryptography (PKC) with a significantly smaller key size and lower computational requirements. The use of pairing on elliptic curves has emerged as a vibrant field of research that provides enhanced security measures for the next generation of cryptographic systems. This thesis explores using ECC and Pairing-Based Cryptosystems (PBC) as effective mathematical tools for achieving high-security levels with minimal key size and computation cost. Specifically, the research aims to analyze Pairing-Friendly Elliptic Curves (PF-EC) and their practicality in resource-constrained environments. It proposes solutions to some of the limitations of existing applications of pairing-based cryptography. The thesis begins by presenting a comprehensive framework for constructing PF-EC and evaluating the practical security of several families of pairing-friendly curves. The study then explores the limitations of Identity-Based Encryption (IBE), a recognized application of pairing-based cryptography. It proposes mechanisms to address issues such as key escrow, secure key issuing, user slandering, and key abusing problems. The proposed solutions include an Escrow-Free Identity-Based Encryption (EF-IBE) scheme secured against confidentiality and an Escrow-Free Identity-Based Signature (EF-IBS) scheme that is forgeable and secure.

Key escrow refers to storing a copy of a cryptographic key with a trusted third party, typically a government agency or some other organization. Key escrow aims to ensure that law enforcement agencies can access encrypted data when necessary, for example, in criminal investigations or national security matters. However, key escrow also raises concerns about privacy and security. If the trusted third party is compromised, the stored keys could be exposed, and unauthorized parties could access sensitive information. This could result in a significant breach of privacy and potentially harm national security. In identity-based cryptography, the key escrow problem arises because a trusted third party, the Private Key Generator (PKG), generates the private keys for all users. This means that the PKG has complete control over the private keys, which raises concerns about the security and privacy of the users. To balance security and privacy concerns, some approaches have been proposed to address the key escrow problem. We propose an efficient democratic identity-based encryption model that balances the government's and users' rights while ensuring security and privacy. The key objective of the proposed scheme is to provide the government with authority to monitor unlawful messages while ensuring the user's privacy for their lawful messages. To achieve this, the scheme involves two entities: PKG and PKPO. The user's partial key is escrowed at PKG, while the partial key is stored at PKPO. The latter provides a privacy service to the user by confusing their signature, which the user with their personal information can only unlock., Comment: M.Tech Dissertation

Additive manufacturing (AM) offers numerous benefits, such as manufacturing complex and customised designs quickly and cost-effectively, reducing material waste, and enabling on-demand production. However, several security challenges are associated with AM, making it increasingly attractive to attackers ranging from individual hackers to organised criminal gangs and nation-state actors. This paper addresses the cyber risk in AM to attackers by proposing a novel semantic-based threat prioritisation system for identifying, extracting and ranking indicators of compromise (IOC). The system leverages the heterogeneous information networks (HINs) that automatically extract high-level IOCs from multi-source threat text and identifies semantic relations among the IOCs. It models IOCs with a HIN comprising different meta-paths and meta-graphs to depict semantic relations among diverse IOCs. We introduce a domain-specific recogniser that identifies IOCs in three domains: organisation-specific, regional source-specific, and regional target-specific. A threat assessment uses similarity measures based on meta-paths and meta-graphs to assess semantic relations among IOCs. It prioritises IOCs by measuring their severity based on the frequency of attacks, IOC lifetime, and exploited vulnerabilities in each domain.

Ontologies play a critical role in Semantic Web technologies by providing a structured and standardized way to represent knowledge and enabling machines to understand the meaning of data. Several taxonomies and ontologies have been generated, but individuals target one domain, and only some of those have been found expensive in time and manual effort. Also, they need more coverage of unconventional topics representing a more holistic and comprehensive view of the knowledge landscape and interdisciplinary collaborations. Thus, there needs to be an ontology covering Science and Technology and facilitate multidisciplinary research by connecting topics from different fields and domains that may be related or have commonalities. To address these issues, we present an automatic Science and Technology Ontology (S&TO) that covers unconventional topics in different science and technology domains. The proposed S&TO can promote the discovery of new research areas and collaborations across disciplines. The ontology is constructed by applying BERTopic to a dataset of 393,991 scientific articles collected from Semantic Scholar from October 2021 to August 2022, covering four fields of science. Currently, S&TO includes 5,153 topics and 13,155 semantic relations. S&TO model can be updated by running BERTopic on more recent datasets

Major families of pairing-friendly elliptic curves, including BN, BLS12, BLS24, KSS16, and KSS18 have recently been vulnerable to number field sieve (NFS) attacks. Due to the recent attacks on discrete logs in F_(q^k ), selecting such curves became relevant again. This paper revisited the topic of selecting pairing-friendly curves at different security levels. First, we expanded the classification given by Freeman et al. [1] by identifying new families that were not previously mentioned, such as a complete family with variable differentiation and new sparse families of curves. We discussed individual curves and a comprehensive framework for constructing parametric families. We estimated the security and assessed families of the pairing-friendly curve to discover families of curves better than BN, KSS, and BLS in terms of the required key size. We also evaluated the complexity of the optimal ate pairing that has never been discussed before, except by Barbulescu et al. [2]. We demonstrated that the recent attack (TNFS) on pairing needs to increase the key size. We compared families of curves in the context of key size and selected a suitable alternative to an elliptic curve.

Pairing is the most powerful tool in cryptography that maps two points on the elliptic curve to the group over the finite field. Mostly cryptographers consider pairing as a black box and use it for implementing pairing-based cryptographic protocols. This paper aims to give the overview of pairing as simple as possible for greenhorn and those who are working and wish to work in the pairing. The paper gives the concrete background of pairing and recommends an appropriate pairing among different choices for constructing pairing-based cryptographic protocols. We also analyze the bandwidth and computational efficiency of pairing and submitting those pairing suitable for implementing a cryptographic protocol for lightweight devices. Additionally, we discuss the extension of bilinear pairing to tri-linear and multilinear pairing and discuss a few assumptions to check their feasibility to implement multilinear pairing.

Recently, an infectious disease, coronavirus disease 2019 (COVID-19), has been reported in Wuhan, China, and subsequently spread worldwide within a couple of months. On May 16, 2020, the COVID-19 pandemic has affected several countries in the world. In this article, we present how the amalgamation of blockchain, cryptography, internet of medical things (IoMT), and artificial intelligence (AI) technologies can address such an issue in the event of the COVID-19 pandemic. Further, we propose a secure AI-based blockchain-assisted IoMT (SAI-BA-IoMT) model for the healthcare system in the COVID-19 crisis. The paper also examines the post-corona crisis that the world could be experienced after the pandemic. Additionally, we exhibit the potential applications of the proposed model to resolve the difficulties originated from coronavirus.