Biblio

Over the last few years, the world has been moving towards digital healthcare, where harnessing medical data distributed across multiple healthcare providers is essential to achieving personalized treatments. Though the efficiency and speed of the diagnosis process have increased due to the digitalization of healthcare data, it is at constant risk of cyberattacks. Medical images, in particular, seem to have become a regular victim of hackers, due to which there is a need to find a feasible solution for storing them securely. This work proposes a blockchain-based framework that leverages the InterPlanetary File system (IPFS) to provide decentralized storage for medical images. Our proposed blockchain storage model is implemented in the IPFS distributed file-sharing system, where each image is stored on IPFS, and its corresponding unique content-addressed hash is stored in the blockchain. The proposed model ensures the security of the medical images without any third-party dependency and eliminates the obstacles that arise due to centralized storage.

People are dependent on Trusted Third Party (TTP) administration based Centralized systems for content sharing having a deficit of security, faith, immutability, and clearness. This work has proposed a file-sharing environment based on Blockchain by clouting the Interplanetary File System (IPFS) and Public Key Infrastructure (PKI) systems, advantages for overcoming these troubles. The smart contract is implemented to control the access privilege and the modified version of IPFS software is utilized to enforce the predefined access-control list. An application framework on a secure decentralized file sharing system is presented in combination with IPFS and PKI to secure file sharing. PKI having public and private keys is used to enable encryption and decryption of every file transaction and authentication of identities through Metamask to cryptographically recognize account ownership in the Blockchain system. A gas consumption-based result analysis is done in the private Ethereum network and it attains transparency, security managed access, and quality of data indicating better efficacy of this work.

With the advancement in the growth of Internet-of-Things (IoT), its number of applications has also increased such as in healthcare, smart cities, vehicles, industries, household appliances, and Smart Grids (SG). One of the major applications of IoT is the SG and smart meter which consists of a large number of internet-connected sensors and can communicate bi-directionally in real-time. The SG network involves smart meters, data collectors, generators, and sensors connected with the internet. SG networks involve the generation, distribution, transmission, and consumption of electrical power supplies. It consists of Household Area Network (HAN), and Neighborhood Area Network (NAN) for communication. Smart meters can communicate bidirectionally with consumers and provide real-time information to utility offices. But this communication channel is a wide-open network for data transmission. Therefore, it makes the SG network and smart meter vulnerable to outside hacker and various Cyber-Physical System (CPS) attacks such as False Data Injection (FDI), inserting malicious data, erroneous data, manipulating the sensor reading values. Here cryptography techniques can play a major role along with the private blockchain model for secure data transmission in smart meters. Hence, to overcome these existing issues and challenges in smart meter communication we have proposed a blockchain-based system model for secure communication along with a novel Advanced Elliptic Curve Cryptography Digital Signature (AECCDS) algorithm in Fog Computing (FC) environment. Here FC nodes will work as miners at the edge of smart meters for secure and real-time communication. The algorithm is implemented using iFogSim, Geth version 1.9.25, Ganache, Truffle for compiling smart contracts, Anaconda (Python editor), and ATOM as language editor for the smart contracts.

With the development of technology, the structure of power grid becomes more and more complex, and the amount of data collected is also increasing. In the existing smart power grid, the data collected by sensors need to be uploaded and stored to the trusted central node, but the centralized storage method is easy to cause the malicious attack of the central node, resulting in single point failure, data tampering and other security problems. In order to solve these information security problems, this paper proposes a new data security storage framework based on private blockchain. By using the improved raft algorithm, partial decentralized data storage is used instead of traditional centralized storage. It also introduces in detail the working mechanism of the smart grid data security storage framework, including the process of uploading collected data, data verification, and data block consensus. The security analysis shows the effectiveness of the proposed data storage framework.

Fog Computing was envisioned to solve problems like high latency, mobility, bandwidth, etc. that were introduced by Cloud Computing. Fog Computing has enabled remotely connected IoT devices and sensors to be managed efficiently. Nonetheless, the Fog-Cloud paradigm suffers from various security and privacy related problems. Blockchain ensures security in a trustless way and therefore its applications in various fields are increasing rapidly. In this work, we propose a Fog-Cloud architecture that enables Blockchain to ensure security, scalability, and privacy of remotely connected IoT devices. Furthermore, our proposed architecture also efficiently manages common problems like ever-increasing latency and energy consumption that comes with the integration of Blockchain in Fog-Cloud architecture.

The Session Initiation Protocol (SIP) is the principal signalling protocol in Voice over IP (VoIP) systems, responsible for initialising, terminating, and maintaining sessions amongst call parties. However, the problem with the SIP protocol is that it was not designed to be secure by nature as the HTTP digest authentication used in SIP is insecure, making it vulnerable to a variety of attacks. The current solutions rely on several standardised encryption protocols, such as TLS and IPsec, to protect SIP registration messages. However, the current centralised solutions do not scale well and cause algorithm overload when encoding and decoding SIP messages. In trying to rectify this issue, we propose in this paper a blockchain-based lightweight authentication mechanism, which involves a decentralised identity model to authenticate the SIP client to the SIP server. Our mechanism uses a smart contract on the Ethereum blockchain to ensure trust, accountability and preserves user privacy. We provided a proof-of-concept implementation to demonstrate our work. Further analysis of this approach's usability, mainly CPU and memory usage, was conducted comparing to IPsec and TLS. Then we discussed our system's security and presented a security analysis. Our analysis proves that our approach satisfies the SIP protocol security requirements.

The energy sector is facing increasing risks, mainly concerning fraudulent activities and cyberattacks. This paradigm shift in risks would require innovative solutions. This paper proposes an innovative architecture based on Distributed Ledger Technologies (Blockchain) and Triple Entry Accounting (X-Accounting). The proposed architecture focusing on new applications of payment and billing would improve accountability and compliance as well as security and reliability. Future research can extend this architecture to other energy technologies and systems like EMS/SCADA and associated applications.

To improve efficiency of stegosystem on blockchain and balance the time consumption of Encode and Decode operations, we propose a new blockchain-based steganography scheme, called Keys as Secret Messages (KASM), where a codebook of mappings between bitstrings and public keys can be pre-calculated by both sides with some secret parameters pre-negotiated before covert communication. By applying properties of elliptic curves and pseudorandom number generators, we realize key derivation of codebook item, and we construct the stegosystem with provable security under chosen hiddentext attack. By comparing KASM with Blockchain Covert Channel (BLOCCE) and testing on Bitcoin protocol, we conclude that our proposed stegosystem encodes hiddentexts faster than BLOCCE does and can decode stegotexts in highly acceptable time. The balanced time consumption of Encode and Decode operations of KASM make it applicable in the scene of duplex communication. At the same time, KASM does not leak sender’s private keys, so sender’s digital currencies can be protected.

The COVID-19 pandemic has recently emerged as a worldwide health emergency that necessitates coordinated international measures. To contain the virus's spread, governments and health organisations raced to develop vaccines that would lower Covid-19 morbidity, relieve pressure on healthcare systems, and allow economies to open. Following the COVID-19 vaccine, the vaccination certificate has been adopted to help the authorities formulate policies by controlling cross-border travelling. To address serious privacy concerns and eliminate the need for third parties to retain the trust and govern user data, in this paper, we leverage blockchain technologies in developing a secure and verifiable vaccination certificate. Our approach has the advantage of utilising a hybrid approach that implements different advanced technologies, such as the self-sovereignty concept, smart contracts and interPlanetary File System (IPFS). We rely on verifiable credentials paired with smart contracts to make decisions about who can access the system and provide on-chain verification and validation of the user and issuer DIDs. The approach was further analysed, with a focus on performance and security. Our analysis shows that our solution satisfies the security requirements for immunisation certificates.

With the development of various technologies, the modern industry has been promoted to a new era known as Industry 4.0. Within such paradigm, smart factories are becoming widely recognized as the fundamental concept. These systems generate and exchange vast amounts of privacy-sensitive data, which makes them attractive targets of attacks and unauthorized access. To improve privacy and security within such environments, a more decentralized approach is seen as the solution to allow their longterm growth. Currently, the blockchain technology represents one of the most suitable candidate technologies able to support distributed and secure ecosystem for Industry 4.0 while ensuring reliability, information integrity and access authorization. Blockchain based access control frameworks address encountered challenges regarding the confidentiality, traceability and notarization of access demands and procedures. However significant additional fears are raised about entities' privacy regarding access history and shared policies. In this paper, our main focus is to ensure strong privacy guarantees over the access control related procedures regarding access requester sensitive attributes and shared access control policies. The proposed scheme called PDAMF based on ring signatures adds a privacy layer for hiding sensitive attributes while keeping the verification process transparent and public. Results from a real implementation plus performance evaluation prove the proposed concept and demonstrate its feasibility.

Blockchain-based cryptocurrencies offer an appealing alternative to Fiat currencies, due to their decentralized and borderless nature. However the decentralized settings make the authentication process more challenging: Standard cryptographic methods often rely on the ability of users to reliably store a (large) secret information. What happens if one user's key is lost or stolen? Blockchain systems lack of fallback mechanisms that allow one to recover from such an event, whereas the traditional banking system has developed and deploys quite effective solutions. In this work, we develop new cryptographic techniques to integrate security policies (developed in the traditional banking domain) in the blockchain settings. We propose a system where a smart contract is given the custody of the user's funds and has the ability to invoke a two-factor authentication (2FA) procedure in case of an exceptional event (e.g., a particularly large transaction or a key recovery request). To enable this, the owner of the account secret-shares the answers of some security questions among a committee of users. When the 2FA mechanism is triggered, the committee members can provide the smart contract with enough information to check whether an attempt was successful, and nothing more. We then design a protocol that securely and efficiently implements such a functionality: The protocol is round-optimal, is robust to the corruption of a subset of committee members, supports low-entropy secrets, and is concretely efficient. As a stepping stone towards the design of this protocol, we introduce a new threshold homomorphic encryption scheme for linear predicates from bilinear maps, which might be of independent interest. To substantiate the practicality of our approach, we implement the above protocol as a smart contract in Ethereum and show that it can be used today as an additional safeguard for suspicious transactions, at minimal added cost. We also implement a second scheme where the smart contract additionally requests a signature from a physical hardware token, whose verification key is registered upfront by the owner of the funds. We show how to integrate the widely used universal two-factor authentication (U2F) tokens in blockchain environments, thus enabling the deployment of our system with available hardware.

Blockchain is opening up new avenues for the development of new sorts of digital services. In this article, we'll employ the transparent Blockchain method to propose a system for collecting data from many sources and databases for use in local and national elections. The Blockchain-based system will be safe, trustworthy, and private. It will assist to know the overall count of the candidates who participated and it functions in the same way as people's faith in their governments does. Blockchain technology is the one that handles the actual vote. We use the secure hash algorithm for resolving this problem and tried to bring a solution through the usage of this booming technology. A centralized database in a blockchain system keeps track of the secure electronic interactions of users in a peer-to-peer network.

An electronic medical record (EMR) is the digital medical data of a patient, and they are healthcare system's most valuable asset. In this paper, we introduce a decentralized network using blockchain technology and smart contracts as a solution to manage and secure medical records storing, and transactions between medical healthcare providers. Ethereum blockchain is employed to build the blockchain. Solidity object-oriented language was utilized to implement smart contracts to digitally facilitate and verify transactions across the network (creating records, access requests, permitting access, revoking access, rejecting access). This will mitigate prevailing issues of current systems and enhance their performance, since current EMRs are stored on a centralized database, which cannot guarantee data integrity and security, consequently making them susceptible to malicious attacks. Our proposed system approach is of vital importance considering that healthcare providers depend on various tests in making a decision about a patient's diagnosis, and the respective plan of treatment they will go through. These tests are not shared with other providers, while data is scattered on various systems, as a consequence of these ensuing scenarios, patients suffer of the resulting care provided. Moreover, blockchain can meliorate the motley serious challenges caused by future use of IoT devices that provide real-time data from patients. Therefore, integrating the two technologies will produce decentralized IoT based healthcare systems.

In proof-of-stake (PoS) blockchains, stakeholders that extend the chain are selected according to the amount of stake they own. In S&P 2019 the "Ouroboros Crypsinous" system of Kerber et al. (and concurrently Ganesh et al. in EUROCRYPT 2019) presented a mechanism that hides the identity of the stakeholder when adding blocks, hence preserving anonymity of stakeholders both during payment and mining in the Ouroboros blockchain. They focus on anonymizing the messages of the blockchain protocol, but suggest that potential identity leaks from the network-layer can be removed as well by employing anonymous broadcast channels.In this work we show that this intuition is flawed. Even ideal anonymous broadcast channels do not suffice to protect the identity of the stakeholder who proposes a block.We make the following contributions. First, we show a formal network-attack against Ouroboros Crypsinous, where the adversary can leverage network delays to distinguish who is the stakeholder that added a block on the blockchain. Second, we abstract the above attack and show that whenever the adversary has control over the network delay – within the synchrony bound – loss of anonymity is inherent for any protocol that provides liveness guarantees. We do so, by first proving that it is impossible to devise a (deterministic) state-machine replication protocol that achieves basic liveness guarantees and better than (1-2f) anonymity at the same time (where f is the fraction of corrupted parties). We then connect this result to the PoS setting by presenting the tagging and reverse tagging attack that allows an adversary, across several executions of the PoS protocol, to learn the stake of a target node, by simply delaying messages for the target. We demonstrate that our assumption on the delaying power of the adversary is realistic by describing how our attack could be mounted over the Zcash blockchain network (even when Tor is used). We conclude by suggesting approaches that can mitigate such attacks.

In the context of Industrial Internet logo analysis, this paper analyzes the feasibility and outstanding advantages of the blockchain technology applied to supply chain data supervision combining the pain spots of traditional supply chain management system and the technical superiority. Although blockchain technology has uprooted some deep-entrenched problems of supply chain data management system, it brings new issues to government supervision in the meanwhile. Upon the analysis of current development and the new problems of blockchain-based supply chain data management system, a new parent-children blockchain-based supply chain data supervision system is proposed, which targets to overcome the dilemma faced by the governmental regulation of supply chain. Firstly, with the characteristics of blockchain including decentralization, non-tampering and non-repudiation, the system can solve the problem puzzling the traditional database about untruthful and unreliable data, and has advantages in managing supply chain and realizing product traceability. The authenticity and reliability of data on the chain also make it easier for the government to investigate and affix the responsibility of vicious incidents. At the same time, the system adopts the parent-children chain structure and the storage mode combining on-chain and off-chain resources to overcome the contradiction between information disclosure requirements of the government and privacy protection requirements of enterprises, which can better meet the needs of various users. Moreover, the application of smart contracts can replace a large number of the manual work like repetitive data analysis, which can make analysis results more accurate and avoid human failure.

Blockchain transactions are signed by private keys. Secure key storage and tamper resistant computing, are critical requirements for deployments of trusted infrastructure. In this paper we identify some threats against blockchain wallets, and we introduce a set of physical and logical countermeasures in order to defeat them. We introduce open software and hardware architectures based on secure elements, which enable detection of cloned device and corrupted software. These technologies are based on resistant computing (javacard), smartcard anti cloning, smartcard self content attestation, applicative firewall, bare metal architecture, remote attestation, dynamic PUF (Physical Unclonable Function), and programming token as root of trust.

Our identity as a human being is determined by the documents, not by appearance or physicality. The most important thing to prove the identity of humans is to show a government-issued document. Generally, from birth to death humans are recognized by documents because they are born with a birth certificate and they die with a death certificate. The main problem with these documents is that, they can be falsified or manipulated by others. Moreover in this digital era, they are stored in a centralized manner, which is prone to a cyber threat. This study aims to develop a blockchain environment to create, verify, and securely share documents in a decentralized manner. With the help of bigchainDB, interplanetary file system (IPFS), and asymmetric encryption, this research work will prototype the proposed solution called blockchain-based digital locker, which is similar to the DigiLocker released by the Department of Electronics and Information Technology (DeitY), Govt. of India. BigchainDB will help in treating each document as an asset by making it immutable with the help of IPFS and asymmetric encryption, where documents can not only be shared but also verified.

As the traditional inverters are transforming toward more intelligent inverters with advanced information and communication technologies, the cyber-attack surface has been remarkably expanded. Specifically, securing firmware of smart inverters from cyber-attacks is crucial. This paper provides expanded firmware attack surface targeting smart inverters. Moreover, this paper proposes a security module for transforming a conventional inverter to a firmware security built-in smart inverter by preventing potential malware and unauthorized firmware update attacks as well as fast automated inverter recovery from zero-day attacks. Furthermore, the proposed security module as a client of blockchain is connected to blockchain severs to fully utilize blockchain technologies such as membership service, ledgers, and smart contracts to detect and mitigate the firmware attacks. The proposed security module framework is implemented in an Internet-of-Thing (IoT) device and validated by experiments.

Blockchain technology has gradually replaced traditional centralized data storage methods, and provided people reliable data storage services with its decentralized and non-tamperable features. However, the current blockchain data supervision is insufficient and the data cannot be modified once it is on the blockchain, which will cause the blockchain system to face various problems such as illegal information cannot be deleted and breach of smart contract cannot be fixed in time. To address these issues, we propose an anonymous editable blockchain scheme based on the reconstruction of the blockchain structure of the SpaceMint combining with the certificateless aggregate signature algorithm. Users register with their real identities and use pseudonyms in the system to achieve their anonymity. If the number of users who agree to edit meets the threshold, the data on the blockchain can be modified or deleted, and our scheme has the function of accountability for malicious behavior. The security analysis show that the proposed certificateless aggregate signature algorithm enjoys the unforgeability under the adaptive selected message attack. Moreover, the method of setting the threshold of related users is adopted to guarantee the effectiveness and security of editing blockchain data. At last, we evaluate the performance of our certificateless aggregate signature algorithm and related schemes in theoretical analysis and experimental simulation, which demonstrates our scheme is feasible and efficient in storage, bandwidth and computational cost.

This paper presents a decentralized messaging system based on blockchain technology. This system allows their users to securely send and receive digital messages in the network. Since the messages stored in a conventional blockchain could be easily read by everyone in the network, under the proposed approach these messages are previously encrypted using public-key cryptography, while the sender and recipient remain anonymous. The proposed system incorporates a browser-based user interface that enable their users to interact seamlessly in a peer-to-peer fashion.

Blockchain become a suitable platform for peer to peer energy trade as it facilitates secure interactions among parties with trust or a mutual trusted 3rd party. However, the scalability issue of blockchains is a problem for real-time energy trade to be completed within a small time duration. In this paper, we use offline channels for blockchains to circumvent scalability problems of blockchains for peer to peer energy trade with small trade duration. We develop algorithms to find stable coalitions for energy trade using blockchain offline channels. We prove that our solution is secure against adversarial prosumer behaviors, it supports real-time trade as the algorithm is guaranteed to find and record stable coalitions before a fixed time, and the coalition structure generated by the algorithm is efficient.

Self-sovereign identities provide user autonomy and immutability to individual identities and full control to their identity owners. The immutability and control are possible by implementing identities in a decentralized manner on blockchains that are specially designed for identity operations such as Hyperledger Indy. As with any type of identity, self-sovereign identities too deal with Personally Identifiable Information (PII) of the identity holders and comes with the usual risks of privacy and security. This study examined certain scenarios of personal data disclosure via credential exchanges between such identities and risks of man-in-the-middle attacks in the blockchain based identity system Hyperledger Indy. On the basis of the findings, the paper proposes the following enhancements: 1) A novel attribute sensitivity score model for self-sovereign identity agents to ascertain the sensitivity of attributes shared in credential exchanges 2) A method of mitigating man-in-the-middle attacks between peer self-sovereign identities and 3) A novel quantitative model for determining a credential issuer's reputation based on the number of issued credentials in a window period, which is then utilized to calculate an overall confidence level score for the issuer.

Access to data at large scales expedites the progress of research in medical fields. Nevertheless, accessibility to patients' data faces significant challenges on regulatory, organizational and technical levels. In light of this, we present a novel approach based on the crowdsourcing paradigm to solve this data scarcity problem. Utilizing the infrastructure that blockchain provides, our decentralized platform enables researchers to solicit contributions to their well-defined research study from a large crowd of volunteers. Furthermore, to overcome the challenge of breach of privacy and mutual trust, we employed the cryptographic primitive of Zero-knowledge Argument of Knowledge (zk-SNARK). This not only allows participants to make contributions without exposing their privacy-sensitive health data, but also provides a means for a distributed network of users to verify the validity of the contributions in an efficient manner. Finally, since without an incentive mechanism in place, the crowdsourcing platform would be rendered ineffective, we incorporated smart contracts to ensure a fair reciprocal exchange of data for reward between patients and researchers.

The advancement and penetration of distributed energy resources (DERs) and renewable energy sources (RES) are transforming legacy energy systems in an attempt to reduce carbon emissions and energy waste. Demand Response (DR) has been identified as a key enabler of integrating these, and other, Smart Grid technologies, while, simultaneously, ensuring grid stability and secure energy supply. The massive deployment of smart meters, IoT devices and DERs dictate the need to move to decentralized, or even localized, DR schemes in the face of the increased scale and complexity of monitoring and coordinating the actors and devices in modern smart grids. Furthermore, there is an inherent need to guarantee interoperability, due to the vast number of, e.g., hardware and software stakeholders, and, more importantly, promote trust and incentivize the participation of customers in DR schemes, if they are to be successfully deployed.In this work, we illustrate the design of an energy system that addresses all of the roadblocks that hinder the large scale deployment of DR services. Our DR framework incorporates modern Smart Grid technologies, such as fog-enabled and IoT devices, DERs and RES to, among others, automate asset handling and various time-consuming workflows. To guarantee interoperability, our system employs OpenADR, which standardizes the communication of DR signals among energy stakeholders. Our approach acknowledges the need for decentralization and employs blockchains and smart contracts to deliver a secure, privacy-preserving, tamper-resistant, auditable and reliable DR framework. Blockchains provide the infrastructure to design innovative DR schemes and incentivize active consumer participation as their aforementioned properties promote transparency and trust. In addition, we harness the power of smart contracts which allows us to design and implement fully automated contractual agreements both among involved stakeholders, as well as on a machine-to-machine basis. Smart contracts are digital agents that "live" in the blockchain and can encode, execute and enforce arbitrary agreements. To illustrate the potential and effectiveness of our smart contract-based DR framework, we present a case study that describes the exchange of DR signals and the autonomous instantiation of smart contracts among involved participants to mediate and monitor transactions, enforce contractual clauses, regulate energy supply and handle payments/penalties.

Blockchains are emerging technologies that propose new business models and value propositions. Besides their application for cryptocurrency purposes, as distributed ledgers of transactions, they enable new ways to provision trusted information in a distributed fashion. In this paper, we present our product tagging solution designed to help Small & Medium Enterprises (SMEs) protect their brands against counterfeit products and parallel markets, as well as to enhance UX (User Experience) and promote the brand and product.Our solution combines the use of DLT to assure, in a verifiable and permanent way, the trustworthiness and confidentiality of the information associated to the goods and the innovative CP-ABE encryption technique to differentiate accessibility to the product's information.