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  • 1.
    Alizadeh, Morteza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Architectural Aspects of Identification in Decentralized Systems2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    High-level systems need identification techniques, where higher security and scalability are considered requirements. Identification plays a significant role in systems where smart electronic devices increase in zero trust and open environments like decentralized systems. Also, decentralization has emerged as one of the most exciting domains in recent years, again after the first Internet was invented. Besides, decentralization in identification systems has gained popularity worldwide since cryptocurrencies became part of businesses. Distributed Ledger Technology (DLT) and Distributed Hash Tables (DHT) can be appropriate decentralized solutions that improve identification to be much more secure, scalable, and trustworthy.

    The decentralized nature of DLT and DHT ensures no single point of failure, making them highly resilient to attacks. Blockchain as a DLT solution can help devices communicate with each other securely and trustably by storing an immutable history of transactions, providing an additional layer of security to identification systems. DHT senable applications to keep files and information immutable in a decentralized manner. DHTs ensure that the data is replicated across multiple nodes, making it highly resilient to data loss. Moreover, mitigating high storage costs without memory limitations is the target of these technologies. In this context, a decentralized system paradigm that combines systems with DLT and DHTs can be highly beneficial.

    This thesis argues for such a paradigm, and the contributions include introducing the term decentralized networks and architectures and demonstrating the feasibility of using blockchain as a DLT solution in real-world scenarios. These scenarios can be applied to the Internet of Things (IoT) or other Peer to Peer networked systems. We explore different architectures in various systems and analyze the interaction in blockchain. This thesis contributes to developing decentralized identification systems that provide users’ trust in an open environment. It presents the challenges associated with decentralized identification, including registry and storage issues, and proposes solutions using DLT and DHT. The immutability of DLT and DHTs provides fast and secure solutions for decentralized identification systems. In particular, we show that a DHT-based architecture is feasible to maintain decentralization while avoiding memory constraints. However, there is still room for improvement in terms of performance. Our investigation shows that combining DHTs with blockchain in decentralized identifiers improves performance.

    By concealing blocks in the private blockchain, we show that query performance is better than other DHT and public blockchain-based solutions without concealed information. Moreover, our results show that DHT performs better than the public blockchain for scenarios with many records.

    These findings highlight the importance of selecting the appropriate technology for decentralized identification systems, considering the specific use case and the number of records to be stored.

    We also consider different decentralized identification systems and platforms built based on the recommendation of W3C Decentralized Identifiers (DIDs). We found low-efficiency issues using this technology, resulting from leveraging public DLT in the data registry part of DIDs. That model has searching time problems if the DLT grows. Finally, this thesis helps to analyze these issues and find better solutions. By choosing the right technology, we can ensure that decentralized identifiers are efficient, secure, and scalable, which enables users to trust them in an open environment.

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  • 2.
    Alizadeh, Morteza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Blockchain and Distributed Hash Table Technology in Decentralized Systems2021Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Internet of Things (IoT) is one of the popular domains in real-time analytics, ma-chine learning, ubiquitous computing, commodity sensors, and embedded systems where remote smart devices play notable roles in smart homes and industry. The information from emerging IoT environments like remotely-controlled objects, autonomous vehicles (AVs), and energy management can produce a huge amount of data. Moreover, under-standing the security in a scalable decentralized IoT environment is a significant issue.Decentralization has become popular again in the world since cryptocurrencies started to be a part of businesses. Therefore, researchers invested in upgrading resources to increase the reliability of these systems among people when most of the activities and human works are now managed by smart electronic devices remotely. Distributed ledgers, Distributed Hash Tables (DHTs), and blockchain technologies are proper decentralized technologies that improve system security, scalability, and trustworthiness. Blockchains contain a group of connected blocks that are digitally signed transactions stored in a decentralized fashion. The DHT technology is another decentralized solution that helps applications keep files and information immutable in a decentralized manner to mitigate the high cost of storage without memory limitations.In this thesis, we argue for a decentralized systems paradigm and, in conjunction with IoT and the blockchain. Our contributions are as follows. First, we introduce the term networks and service architectures and how it is possible to use blockchain in the real world. We consider different architectures in IoT systems and show the blockchain en-counter with the IoT and the resulting behavior. Second, we detect most of the frequent types of attacks in IoT related to using blockchain in the systems. We also describe how the blockchain works and illustrate a variety of security problems in systems. Fur-thermore, we discuss how the blockchain solves security problems by comparing different blockchains and explain how users handle their communication without third-party de-pendence. As our third contribution, we propose a novel architecture that consists of finding global identification in distributed applications and enable decentralized systems to be more secure with the help of blockchain technology. We also validate the proposed architecture and novel decentralized application development to evaluate high efficiency by combining blockchain, DHT, and biometric technologies.

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  • 3.
    Alizadeh, Morteza
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    A Survey of Secure Internet of Things in Relation to Blockchain2020In: Journal of Internet Services and Information Security (JISIS), ISSN 2182-2069, E-ISSN 2182-2077, Vol. 10, no 3, p. 47-75Article in journal (Refereed)
    Abstract [en]

    Distributed ledgers and blockchain technologies can improve system security and trustworthiness by providing immutable replicated histories of data. Blockchain is a linked list of blocks containing digitally signed transactions, a cryptographic hash of the previous block, and a timestamp stored in a decentralized and distributed network. The Internet of Things (IoT) is one of the application domains in which security based on blockchain is discussed. In this article, we review the structure and architectures of distributed IoT systems and explain the motivations, challenges, and needs of blockchain to secure such systems. However, there are substantial threats and attacks to blockchain that must be understood, as well as suitable approaches to mitigate them. We, therefore, survey the most common attacks to blockchain systems and the solutions to mitigate them, with the objective of assessing how malicious these attacks are in the IoT context.

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  • 4.
    Alizadeh, Morteza
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Comparative Analysis of Decentralized Identity Approaches2022In: IEEE Access, E-ISSN 2169-3536, Vol. 10, p. 92273-92283Article in journal (Refereed)
    Abstract [en]

    Decentralization is essential when trust and performance must not depend on a single organization. Distributed Ledger Technologies (DLTs) and Decentralized Hash Tables (DHTs) are examples where the DLT is useful for transactional events, and the DHT is useful for large-scale data storage. The combination of these two technologies can meet many challenges. The blockchain is a DLT with immutable history protected by cryptographic signatures in data blocks. Identification is an essential issue traditionally provided by centralized trust anchors. Self-sovereign identities (SSIs) are proposed decentralized models where users can control and manage their identities with the help of DHT. However, slowness is a challenge among decentralized identification systems because of many connections and requests among participants. In this article, we focus on decentralized identification by DLT and DHT, where users can control their information and store biometrics. We survey some existing alternatives and address the performance challenge by comparing different decentralized identification technologies based on execution time and throughput. We show that the DHT and machine learning model (BioIPFS) performs better than other solutions such as uPort, ShoCard, and BBID.

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  • 5.
    Alizadeh, Morteza
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Decentralized Identifiers using Distributed Ledger Technologies2023In: 2023 IEEE Asia-Pacific Conference on Computer Science and Data Engineering (CSDE), IEEE, 2023Conference paper (Refereed)
    Abstract [en]

    Decentralized identification is an interesting topic for Internet-based systems. Although the use of centralized systems for identification is prevalent, there is still a need for decentralized identification systems that do not rely on a centralized entity. We propose using Distributed Ledger Technology (DLT) to fulfill the needs. Although DLT and Distributed Hash Table (DHT) can be used as technologies in Decentralized Identifiers (DIDs), immutability and the growth of transactions are still challenging. This paper investigates DIDs under the W3C standard and DLT-based technology as one of the solutions for verifiable data registries in DIDs. We evaluate our proposed solution by comparing three models wrt. query time for verifiable data registries. Our proposed architecture for data registry achieves better query time by concealing old transactions from the main DLT.

  • 6.
    Alizadeh, Morteza
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    DHT- and Blockchain-based Smart Identification for Video Conferencing2022In: Blockchain: Research and Applications, ISSN 2096-7209, Vol. 3, no 2, article id 100066Article in journal (Refereed)
    Abstract [en]

    Video conferencing applications help people communicate via the Internet and provide a significant and consistent basis for virtual meetings. However, integrity, security, identification, and authentication problems are still universal. Current video conference technologies typically rely on cloud systems to provide a stable and secure basis for executing tasks and processes. At the same time, video conferencing applications are being migrated from centralized to decentralized solutions for better performance without the need for third-party interactions. This article demonstrates a decentralized smart identification scheme for video conferencing applications based on biometric technology, machine learning, and a decentralized hash table combined with blockchain technology. We store users' information on a distributed hash table and transactional events on the distributed ledger after identifying users by implementing machine learning functions. Furthermore, we leverage distributed ledger technology's immutability and traceability properties and distributed hash table unlimited storage feature to improve the system's storage capacity and immutability by evaluating three possible architectures. The experimental results show that an architecture based on blockchain and distributed hash table has better efficiency but needs a longer time to execute than the two other architectures using a centralized database.

  • 7.
    Alizadeh, Morteza
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Efficient Decentralized Data Storage Based on Public Blockchain and IPFS2020In: 2020 IEEE Asia-Pacific Conference on Computer Science and Data Engineering (CSDE), IEEE, 2020Conference paper (Refereed)
    Abstract [en]

    Blockchain technology has enabled the keeping of a decentralized, tamper-proof, immutable, and ordered ledger of transactional events. Efforts to leverage such a ledger may be challenging when data storage requirements exceed most blockchain protocols’ current capacities. Storing large amounts of decentralized data while maintaining system efficiency is the challenge that we target. This paper proposes using the IPFS distributed hash table (DHT) technology to store information immutably and in a decentralized manner to mitigate the high cost of storage. A storage system involving blockchain and other storage systems in concert should be based on immutable data and allow removal of data from malicious users in the DHT. Efficiency is improved by decreasing the overall processing time in the blockchain with the help of DHT technology and introducing an agreement service that communicate with the blockchain via a RESTful API. We demonstrate the applicability of the proposed method and conclude that the combination of IPFS and blockchain provides efficient cryptographic storage, immutable history and overall better efficiency in a decentralized manner.

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  • 8.
    Alizadeh, Morteza
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Performance Analysis of Verifiable Data Registry Solutions for Decentralized Identifiers2022In: 2022 IEEE Asia-Pacific Conference on Computer Science and Data Engineering (CSDE), IEEE, 2022Conference paper (Refereed)
    Abstract [en]

    User identification in decentralized systems is a demanding task. Identification systems should work resiliently and have efficient performance. Moreover, identification systems should protect the data that they must store against hackers and saboteurs. Keeping a system with decentralized identification without any intervention in the middle has attracted attention to improve earlier centralized identification systems. Decentralized Identifiers (DIDs) constitute a solution for identification divided into different modules. The verifiable data registry is one of the main parts of this technology, which is distributed storage of identity properties. We analyze the decentralized identification data registry and compare the performance of verifiable data registry based on blockchain and the Distributed Hash Table (DHT) on different scales of systems. Our evaluation results show that DHT has better performance. Furthermore, a model based on DHT shows that in addition to immutable storage and faster query time, it makes systems handle or search in data storage with lower searching time compared to Ethereum Blockchain as another immutable secure technology. Finally, our results show that DHT is a better solution than other models in different scenarios. Although blockchain has promising results on a small scale, it still has problems with storage and query time in large-scale systems.

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  • 9.
    Altmann, Peter
    et al.
    Department of Industrial Systems, RISE Research Institutes of Sweden AB, SE-16440 Kista, Sweden.
    Abbasi, Abdul Ghafoor
    Department of Industrial Systems, RISE Research Institutes of Sweden AB, SE-16440 Kista, Sweden.
    Schelén, Olov
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Andersson, Karl
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Alizadeh, Morteza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Creating a Traceable Product Story in Manufacturing Supply Chains Using IPFS2020In: 2020 IEEE 19th International Symposium on Network Computing and Applications (NCA) / [ed] Aris Gkoulalas-Divanis, Mirco Marchetti, Dimiter R. Avresky, Boston/New York: IEEE, 2020, p. 11-18Conference paper (Refereed)
    Abstract [en]

    Evolving traceability requirements increasingly challenge manufacturing supply chain actors to collect tamperproof and auditable evidence about what inputs they process, in what way these inputs are used, and what the resulting process outputs are. Traceability solutions based on blockchain technology have shown ways to satisfy the requirements of creating a tamper-proof and auditable trail of traceability data. However, the existing solutions struggle to meet the increasing storage requirements necessary to create an evidence trail using manufacturing data. In this paper, we show a way to create a tamper-proof and auditable evolving product story that uses a decentralized file system called the InterPlanetary File System (IPFS). We also show how using linked data can help auditors derive a traceable product story from such an accumulating evidence trail. The solution proposed herein can supplement existing blockchain-based traceability solutions and enable traceability in global manufacturing supply chains where forming a consortium incurs prohibitive costs and where storage requirements are high.

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