Blockchain Papers

Anees Ara, Avinash Sharma, Dharminder Yadav

User authentication is a measurement challenge for handheld devices and online accounts such as bank accounts, social media accounts etc. because illegal access results in money loss and user privacy. Individual devices, online financial services, and intelligent spaces are three significant areas of concern for customer authentication procedures. Three ways have been identified for authentication factors: i) knowledge-factor, ii) Inherence factor, and iii) possession-factor. This study investigates two-way user authentication through image processing. CNN, RCNN, and Deepface are deep learning algorithms used for image recognition. We used imagechain for image storage and Blockchain for personal information storage (mobile number) to secure the database. The database is stored on an Ethereum-based blockchain. After determining whether the image is fake or real, match the webcam image with the imagechain; if both images match, the one-time password is given to the user’s cellphone number for login access. For image processing, Opencv is employed, and the Python library is used to execute machine and deep learning algorithms for user authentication. Test the proposed model on the 10 to 100 users for authentication. Accuracy of this experiment is 75.35, 76.33, 98.18 and cosine similarities of images are much better between images, but in case of fake image identification it achieved 97.35 % accuracy.

Frederik Temmermans, Deepayan Bhowmik, Fernando Pereira, Touradj Ebrahimi

Advances in deep neural networks (DNN) and distributed ledger technology (DLT) have shown major influence on media security, authenticity and privacy. Current deepfake techniques can produce near realistic media content which can be used in both good and bad intended use cases. At the same time, DLTs are finding their way in the industry as fair, transparent and reliable means for content distribution. In particular non-fungible tokens (NFTs) are emerging in the digital art market. However, such new developments also introduce new challenges, including the need for robust and reliable metadata, a mechanism to secure the media and associated metadata, means to verify authenticity and interoperability between various stakeholders. This paper identifies emerging challenges in fake media and NFT, and proposes a novel framework to effectively cope with secure media applications allowing for a structured, systematic, and interoperable solution. The framework relies on an architecture that is modular, flexible, extensible, and scalable in the sense that it can be implemented in both lighter as well as more feature-rich and more complex configurations depending on the underlying application, needed features and available resources, while enabling products and services in various ecosystems with desired trust and security capabilities. The framework is inspired by activities and developments within JPEG standardisation related to security, authenticity and privacy.

Marah Mohammed Taha, Mafaz Alanezi

A blockchain is a decentralized architecture that most cryptocurrencies rely on duplicating and distributing a digital ledger of transactions across a peer-to-peer network with built in security to increase the trust and integrity of the transactions. Due the benefits of this technology, we review Recently published papers to explain its main types (public, private, hybrid) and extract the main characteristics of each one separately to know what is the suitable type depended on environment conditions and predefined requirements. and review of the popular cryptocurrencies working environments, which are generally considered one of the basic applications depended on the blockchain.

Yasser Asrul Ahmad, Muhammad Fadhil Shaharuddin, Teddy Surya Gunawan, Fatchul Arifin

Digitization of a secure electoral system capable of ensuring fairness and privacy has been a long-standing challenge for a variety of reasons. One is the system's reliance on a third-party organization to manage and verify election results, rendering it insecure. There is a possibility that data will be altered during the election process. As a result, a decentralized e-voting system application capable of verification will be developed in this work using blockchain technology. The Ethereum network and the Truffle framework will be used to implement smart contracts as self-executing electoral agreements. The Ganache (local blockchain) network design demonstrated that the prototype is capable of recording every voting transaction on the network without the use of a central database. The voter can verify the election result by inspecting each voting transaction on the local blockchain. The proposed design will ensure that all voting transactions are stored in a decentralized database, ensuring that no administrative control over the ballot is exercised.

Mohammad Salahuddin, Priyesh Kadbe, Rajat Wanjarkar

In place of traditional electoral systems, the implementation of e-voting systems is widely adopted which still has major problems in the results. Online voting is an alternative to the old paper voting system and today's popular Electronic Vote Machine (EVM). E-voting systems are very susceptible to manipulation issues, such as alteration of election results by hacking or by the manufacturer of the voting system. To solve this problem, we use distributed ledger technology to create a voting application that is accessible to everyone and everywhere. Blockchain, which is the technology behind the first Bitcoin cryptocurrency, has attracted a lot of attention globally in recent years. This paper proposes a blockchain-based voting system that removes some limitations of existing voting systems. The application is based on the Ethereum blockchain which makes the entire system secure and immutable in nature. The presented implementation is suitable for small-scale elections such as inside corporate homes, meeting rooms, and more.

V Lalitha, S. Samundeswari, R Roobinee, Lakshme S Swetha

Casting a vote is not only the right of a citizen but also a responsibility of the citizen. The citizens of a country get an opportunity to vote for their representatives who will represent the needs and suggestions of citizens. These representatives are elected through the process called elections. The traditional electoral system necessitates the actual presence of the voter which causes discomfort to the physically challenged people. Also, there are chances of vote tampering. This paper discusses the proposed solution that will solve the above problems. Our proposed solution is to use an Online Voting System using Ethereum Blockchain. This web-based voting system helps the voters to vote from any location. The system validates the voters with the help of their Aadhar cards linked with their voter id. After which the system requires the voters to scan their face and fingerprint which will be verified with the data in the database. Blockchain technology encrypts the vote and thus it prevents every vote from tampering. It makes sure that a voter can vote only once for one candidate. The system fetches the election results quickly and thus reduces the labour cost and counting errors.

S Arunprathap, R Nithya, S Nivetha

Blockchain technology provides high levels of data security, as well as decentralization, open and transparent network infrastructure, and cheap operational costs. Even in the generally conservative world of finance, these excellent traits make blockchain an extremely practical and in-demand solution and also in constrained banking business. Banking activities are inextricably linked to deposits and loans. Because the deposits are not controlled by a single company, a distributed ledger-based system for loans and deposits, is decentralized and cannot go bankrupt. Use the block chain technique to validate and trace transactions for online commerce. Block chains were created to handle certain transactions with specific validation needs. A value chain's systems all save blocks of time-stamped transactions. A blockchain is a decentralized ledger in which all participants can see each other's transactions. A blockchain is a distributed ledger that records asset trades between members of a community. The connection between two blocks is made using the SHA-256 algorithm. Block chain breaks data into little parts and distributes them around a network of computers instead of storing data in a single spot or uploading it to a cloud service. It is a decentralized digital transaction ledger with no central control point. Data will not be lost if one or two nodes fail because each computer (or node) has a full duplicate of the ledger. It effectively eliminates the middleman, as there is no need to seek the assistance of a third-parties to conduct a transaction. Instead of putting their faith Users can trust a decentralized, immutable ledger in a vendor or service provider. Also, use the fog server system to save duplicate storage and prevent unauthorized access.

Runkai Yang, Xiaolin Chang, Jelena Mišić, Vojislav B. Mišić · 5 authors

Fork after withholding (FAW) attack is an easy-to-conduct attack in the Bitcoin system and it is hard to be detected than some attacks like selfish mining and selfholding attacks. The previous studies about FAW attack made some strong assumptions, such as no propagation delay in the network.

Hongyu Zhu, Libo Feng, Jianzhao Luo, Yani Sun · 6 authors

The traditional electronic voting (e-voting) has the problems of dead vote, repetition and missing registration, which cannot reflect the voting result correctly, objectively and fairly. With the booming development of blockchain in recent years, blockchain technology provides a new solution in the field of e-voting. Multi-District election is an important method of election in real life, e.g. in US presidential election. Inspired by the electoral college system, we propose a blockchain-based e-voting scheme for multi-district election. First, we propose a blockchain-based voter registration method that all voters are authenticated by the blockchain system. Second, we design a two-layer blockchain architecture, where the lower layer records the votes of voters in each district and the higher layer records the votes of electors. Then we describe the voting process and evaluate the security and availability of the proposed scheme. The experimental results show that the proposed scheme can satisfy the needs of multi-district election.

Qiuyun Lyu, Hao Li, Renjie Zhou, Jilin Zhang · 6 authors

Online advertising, which depends on consumers’ click, creates revenue for media sites, publishers, and advertisers. However, click fraud by criminals, i.e., the ad is clicked either by malicious machines or hiring people, threatens this advertising system. To solve the problem, many schemes are proposed which are mainly based on machine learning or statistical analysis. Although these schemes mitigate the problem of click fraud, several problems still exist. For example, some fraudulent clicks are still in the wild since their schemes only discover the fraudulent clicks with a probability approaching but not 100%. Also, the process of detecting a click fraud is executed by a single publisher, which makes a chance for the publisher to obtain illegal income by deceiving advertisers and media sites. Besides, the identity privacy of consumers is also exposed because the schemes deal with the plain text of consumers’ real identity. Therefore, in this paper, a blockchain-based click fraud detection and prevention scheme (BCFDPS) for online advertising is proposed to deal with the above problems. Specifically, the BCFDPS mainly introduces bilinear pairing to implicitly verify whether a consumer’s real digital identity is contained in a click message to significantly avoid click fraud and employs a consortium blockchain to ensure the transparency of the detection and prevention process. In our scheme, the clicks by machines or fraud ones by a human can be accurately detected and prevented by media sites, publishers, and advertisers. Furthermore, ciphertext-policy attribute-based encryption is adopted to protect the identity privacy of consumers. The implementation and evaluation results show that compared with the existing click fraud detection and prevention schemes based on machine learning and statistical analysis, BCFDPS achieves detection of each fraudulent click with a probability of 100% and consumes lower computation cost; furthermore, BCFDPS adds functions of consumers’ privacy protection and click fraud detection and prevention, compared to the existing blockchain-based online advertising scheme, by introducing limited communication cost ( 4,984 bytes) at lower storage cost.

Sumeet Gupta, M. K. Sharma, Rupinder Singh, Hashem Ali Almashaqbeh · 6 authors

Due to the proliferation of smart devices in the Internet of Things (IoT) connections, significant security concerns for device-to-device connectivity have been raised. Blockchain is a decentralized and shareable technology that may be used to overcome security challenges in 5 g networking and Internet of Things networks, among other things. This research provides a multi-layer Blockchain Security model that may be used to protect IoT networks while also making their implementation simpler. The grouping idea is used to ease the multi-layer design. Inside this IoT network, the K-unknown groups are formed utilizing methodologies that use hybrid Adaptive Computational Algorithms as well as Evolutionary Techniques & Genetic Algorithms. The group leaders selected are in charge of regional identification & permission. Communications among-st group chiefs & appropriate core networks are facilitated by privately run blockchain implementations. A blockchain of this kind improves reputation verification & confidentiality while also serving as a networking identification method. For the suggested concept construction, the accessible Hyperledger Fabric Blockchain technology is used. Ground stations use a worldwide blockchain architecture to seamlessly interact with one another.

Na Li

In the last two years, due to the pandemic and restrictive measures, the dependence of music creators and artists on the Internet, where they could promote their work, organize live streaming concerts, and talk to the public, has increased and expanded even more and seeks higher revenue from digital music platforms. An important issue that arises from the above statement is protecting the authors' copyright regarding the uses and sharing in the digital services of their works with protected content. Although circulated in digital information, the protected content is not information but a product of ethical and commercial value. While it has an intangible owner and it owes its existence to the creative idea of its creator, it is not an idea. The imposition of legal and commercial conditions on its movement cannot be associated with any restrictions on the free movement of information, as it is not related to them. In general, the unauthorized exchange of digital music files via peer-to-peer violates copyright law. The exchange of files is unauthorized, as it does not have the relevant permission from the creators and beneficiaries and is therefore illegal. With this in mind, this paper proposes a highly effective way of protecting the copyright of music technology, which is based on the widespread use of artificial intelligence, blockchain, and cryptography technologies. Specifically, an advanced blockchain model based on Hyperledger Fabric is introduced, which, however, uses Quantum Homomorphic Encryption and Quantum Zero-Knowledge Arguments. Music files are implemented as Nonfungible Tokens (NFTs), which activate smart contracts. Finally, an advanced collaborative filtering algorithm provides recommendations for effectiveness in securing the copyrights of music industry creators. A specialized scenario was built to model the proposed system to verify the degree of protection on music intellectual property in developing a security simulation with an innovative consensus-based zero knowledge and the quantum fully homomorphic encryption technique. Experiment results show that this technique can aid in implementing a technologically aware system capable of providing a powerful answer to a current real-world problem.

Syed Anas Ansar, Swati Arya, Shruti Aggrawal, Jaya Yadav · 5 authors

Nowadays, Blockchain technology has also drawn mammoth attention as it is currently triggering multiple projects. This technology is the prevalent technology that allows Bitcoin to operate. Bitcoin has already cemented itself as a popular virtual currency, and it will soon become a pressing requirement for citizens. Furthermore, with digital currencies proliferating all over the world, security must not be overlooked, especially when there have been numerous attacks and security vulnerabilities on bitcoin's blockchain. However, the lucrative system has drawn opponents and attackers who are continually attempting to exploit flaws in the technology in order to get profit. This paper contemplates the bitcoin's transaction process, with a focus on obscuring the true identities of clients and their coins prior to transacting, and then elucidating on the following: SHA-256 function, the primary threats to Bitcoin's security, along with some countermeasures to be undertaken.

Bryan A. White, Aniket Mahanti, Kalpdrum Passi

Non Fungible Tokens (NFTs) are unique digital identifiers used to represent ownership of various cryptoassets such as music, artwork, collectibles, game assets and allow for an unalterable and provable chain of creation and ownership. The market for NFTs exploded in 2021, and much of the public is being exposed to this new digital ownership medium for the first time. While uptake of this new medium is relatively slow, we feel the prospects of blockchain technology are up-and-coming. NFTs are still largely misunderstood by the wider community, and as such, this provides a fascinating opportunity to explore the NFT marketplace in greater depth. We analyzed sales data from OpenSea - the NFT marketplace with the most extensive user base and sales volume. Our study considered 5.25 million sales that occurred between January 1, 2019, and December 31, 2021. We first lead by presenting an overview of our data collection process and summarizing key statistics of the data set. We examine user behaviour in the market to show that a small subset of heavy-hitters is driving massive growth. Secondly, we review the economic activity within the network to show how these power users drive extreme price volatility within the Art and Collectible categories. Lastly, we review the network of buyers and sellers to show that despite the sparsity that exists in the network, communities of users are forming, and most power users tend to congregate in these structures. These findings shed light on areas of the NFT marketplace that have been relatively unexamined and provide a multi-level analysis of a multi-billion dollar market.

S Ezhilmathi, S. Selvakumara Samy

Bitcoin is a decentralized peer-to-peer (P2P) cryptocurrency system with an innovative payment network. For blockchain applications, ECDSA is formed with public and private keys, especially in Bitcoin, which uses an elliptic curve in a cryptography standard known as Secp256k1 to ensure funds are spent by legitimate owners. Despite the fact that ECDSA is a key component of Bitcoin transactions, today's criminals employ pseudonymous addresses, which make it impossible to track unlawful activity because they don't maintain real-world identities. Bitcoin Fog, Helix Mix, and other mixing services are supposed to provide transaction privacy. However, these services are commonly utilized for concealment, it is more difficult to track criminals. First, using time-frequency analysis, features can be recovered at the network, account, or transaction level to create attributed temporal heterogeneous network Motifs and characterize many forms of address patterns. To increase the performance of evaluation metrics, we introduced a decision-tree machine learning approach for the categorization of bitcoin mixing services from unlabeled addresses in this work. Experiments with bitcoin Kaggle datasets are frequently used to determine the success of our categorization approach.

Ankala Stallin, Kagga Pavan Kumar, B. Prabha

Digital media is one of the most shared, influenced and highly used forms of the medium in the 21stcentury. Its presence ranges from simple images, shared in a Peer-to-Peer network to a world-renowned newspaper that provides second to second update on events around the world at the comfort zone. With this ease-of-access and anonymity it is easier than ever to copy and claim someone else’s work as their own. This nefarious practice of copyright infringement has high stakes when monetization is involved, especially in a high-stake venture such as NFT (Non-fungible Token) based artworks that are not only meant to be unique but also should benefit the artists not the people who masquerades as the true owner of the said art. To avoid such malpractices, watermarking is one of the oldest yet most used methods of authentication techniques for images. It is more effective if it’s hidden in plain sight (most of the times within the image’s meta-data,) so that it wouldn’t affect the appearance of the image but provides the impact, nonetheless. Discrete Cosine Transform (DCT) algorithm based hidden image watermarking is implemented to focus more on domain frequency. Furthermore, Domain Frequency is extracted to transform the original image and to add the watermark. DCT is implemented to enhance the rate of watermark processing. The whole project, in their individual modules discuss Image processing, encoding the said output with the watermark image and decrypting the said resultant to verify the watermark. As said before, the applications are vast with the emerging technology of Web3 and blockchain backed projects.

Luca Turchet, Chan Nam Ngo

Blockchain technology is impacting several industries, including the creative industries and those operating in the Internet of Things (IoT). Lately, researchers' attention has been devoted to the application of blockchain in the recorded music industry. However, thus far, no research has investigated the use of such technology in the Internet of Musical Things (IoMusT). The IoMusT is a new area emerging in industry and academy as an extension of the IoT to the musical domain. The IoMusT itself, as the IoT, is a distributed network of musical things, which are objects augmented with information and communication technologies serving a musical purpose. The IoMusT vision requires, above all, IoT features such as decentralization, seamless authentication, transparency, data integrity and privacy, and self-maintenance, as well as the musical domain features such as efficient handling of copyrights and speed of royalties payment. Such features can be brought by blockchain. In this paper, we investigate the integration of blockchain technology with the IoMusT, and we name such synthesis “Blockchain-based IoMusT”. We present a vision for this new paradigm in terms of the novel opportunities that are enabled, and we propose a set of application scenarios enabled by technological integration. Finally, we outline the open research directions in this promising area.

Swapna Donepudi, K. Thammi Reddy

Block chain is a distributed ledger technology that stores data on several servers globally, and anyone on the authenticated network can see data in near real-time. Data stored on a Block chain is immutable, time-stamped, unanimous, decentralized, secure, irreversible, fast, and consensus-dependent. Due to these benifits many of the real life software applications are adopting to block chain technology. Online voting process demands all the advantages offered by block chain technology, because block chain uses type of Distributed Ledger Technology that uses a cryptographic signature known as a hash to record transactions. There are numerous block chain based voting mechanicams/strategies have been proposed by various researchers. This paper aims at evaluating block chain based voting mechanisms versus a block chain voting strategy named “Performance Driven Framework for Mass e-Voting” strategy proposed by the authors of this paper [1] using Hyperledger Caliper. This paper also discusses detail the advantages, disadvantages and future possible research directions.

Lu Chen, Xin Zhang, Zhixin Sun

Blockchain is a distributed ledger that combines technologies such as timestamp, cryptography, consensus mechanism, and peer-to-peer network. In the field of data recording and management, the blockchain data query scheme based on smart contracts consumes a lot of resources, and blockchain platforms that do not support smart contracts cannot achieve convenient data query. This study proposes a blockchain data sharing query scheme based on threshold secret sharing. The secret elements used to query data are shared through the Blakley space plane equation to limit the rights of the inquirer, ensuring the security of blockchain data query. At the same time, the Blakley space plane equation coefficient matrix is used to segment the data to be uploaded to the blockchain. It solves the problem that the data cannot be directly stored in the block due to their large size. It facilitates data uploading to the blockchain. The experimental results show that the additional time consumption of the secret sharing and recovery, data segmentation, and reconstruction of this scheme is much less than the block generation time. Therefore, this solution will not affect the normal operation of blockchain applications and can improve the security and the fault tolerance rate of data query.

Subhas Barman, Subhas Barman, Samiran Chattopadhyay, Debasis Samanta · 6 authors

Abstract The electronic health record is the most sensitive data which needs a secure framework to protect it from data breaching. Recently, blockchain‐based platforms are used in healthcare services for data security, data sharing and availability of immutable data during medico‐legal verification. In this paper, a blockchain‐based approach for securing electronic health records using elliptic curve cryptography (ECC) and a biometric‐based fuzzy commitment scheme is proposed. The proposed approach addresses common issues of blockchain, namely scalability, integrity, confidentiality and decentralization of the ledger. The security of the proposed scheme was verified using the Random Oracle model. The block time for a variable number of transactions per block was measured and compared with the block time of the existing approaches. Also, the proposed approach was compared with the existing approaches with reference to various security features.

Ardeshir Shojaeinasab, Amir Pasha Motamed, Behnam Bahrak

Abstract Cryptocurrencies, particularly Bitcoin, have garnered attention for their potential in anonymous transactions. However, their anonymity has often been compromised by deanonymization attacks. To counter this, mixing services have been introduced. While they enhance privacy, they obscure fund traceability. This study seeks to demystify transactions linked to these services, shedding light on pathways of concealed and laundered money. We propose a method to identify and classify transactions and addresses of major mixing services in Bitcoin. Unlike previous research focusing on older techniques like CoinJoin, we emphasize modern mixing services. We gathered labelled data by transacting with three prominent mixers (MixTum, Blemder, and CryptoMixer) and identified recurring patterns. Using these patterns, an algorithm was created to pinpoint mixing transactions and distinguish mixer‐related addresses. The algorithm achieved a remarkable recall rate of 100%. Given the lack of clear ground truth and the vast number of unlabelled transactions, ensuring accuracy was a challenge. However, by analyzing a set of non‐mixing transactions with our model, it was confirmed that the high recall rate was not misleading. This work provides a significant advancement in monitoring mixing transactions, presenting a valuable tool against fraud and money laundering in cryptocurrency networks.

Mohammed Shuaib, Noor Hafizah Hassan, Sahnius Usman, Shadab Alam · 8 authors

Providing an identity solution is essential for a reliable blockchain-based land registry system. A secure, privacy-preserving, and efficient identity solution is essential but challenging. This paper examines the current literature and provides a systematic literature review in three stages based on the three research questions (RQ) that show the assessment and interpretation process step by step. Based on the parameters and RQ specified in the research methodology section, a total of 43 primary articles have been selected from the 251 articles extracted from various scientific databases. The majority of these articles are concerned with evaluating the existing self-sovereign identity (SSI) solutions and their role in the blockchain-based land registry system to address the compliance issues in the existing SSI solutions with SSI principles and find the best possible SSI solution to address the identity problems in the land registry. The existing digital identity solutions cannot handle the requirements of the identity principle and are prone to various limitations like centralization and dependency on third parties that further augment the chance of security threats. SSI has been designed to overcome these limitations and provide a secure, reliable, and efficient identity solution that gives complete control to the users over their personal identity information (PII). This paper reviews the existing SSI solutions, evaluates them based on the SSI principles, and comes up with the best possible SSI solution for a blockchain-based land registry system. It further provides a detailed investigation of each SSI solution to present its functionalities and limitations for further improvement.

Dimitris Mouris, Nektarios Georgios Tsoutsos

Digital manufacturing (DM) is actively adopted to the production lifecycles of a variety of critical industries, and this rapid growth has resulted in exponential increase of 3D computer-aided design (CAD) models. Unfortunately, counterfeiting of intellectual property becomes a prominent threat as many 3D designs are accessible online, combined with the proliferation of cheap consumer 3D printers that enable malicious actors to produce non-authentic parts. State-of-the-art techniques to secure manufacturing processes mostly rely on watermarking, which embeds hidden information inside CAD models to prove ownership and authenticity. Nevertheless, such techniques tamper with the model itself, while existing attacks allow removing such watermarks altogether. To address these shortcomings, we integrate signal processing and cryptographic techniques and describe a tailored solution for CAD model ownership and supply chain management. Our approach generates unique identifiers for 3D designs using frequency-domain transforms and employs non-fungible tokens (NFTs) that persist on public distributed ledgers. Our NFTs are implemented on the Ethereum blockchain using smart contracts and their functionality is twofold: (a) authenticate the owner of a CAD model, and (b) enable ownership transfer. To validate our technique, we deployed our smart contract on Ethereum's proof-of-work Ropsten network and demonstrated the applicability of our methodology.

Jamil Asim, Adnan Shahid Khan, Rashad Mahmood Saqib, Johari Abdullah · 9 authors

There are continued advances in the internet and communication fields regarding the deployment of 5G-based applications. It is expected that by 2030, 6G applications will emerge as a continued evolution of the mobile network. Blockchain technology is one of the leading supporting technologies predicted to provide a secure and unique network to 6G-enabled devices, transactions, and applications. It is anticipated that the 6G mobile networks will be virtualized, have cloud-based systems, and aim to be the foundation for the Internet of Everything. However, along with the development of communication technologies, threats from malicious parties have become more sophisticated, making security a significant concern for the 6G era in the future. Despite enormous efforts by researchers to improve security and authentication protocols, systems still face novel intrusion and attacks. Recently, multifactor authentication techniques (MFA) have been deployed as potential solutions to attacks in blockchains. The 6G applications and the cellular network have specific vulnerabilities that need to be addressed using blockchain-based MFA technologies. The current paper is a systematic review that discusses the three technologies under consideration; then, several studies are reviewed that discuss MFA techniques in general and use blockchains as potential solutions to future security and authentication issues that may arise for 6G applications.