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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Modern technologies of decentralized databases, authentication, and authorization methods⋆</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Petro Petriv</string-name>
          <email>petro.p.petriv@lpnu.ua</email>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Ivan Opirskyy</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Nataliia Mazur</string-name>
          <email>n.mazur@kubg.edu.ua</email>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Borys Grinchenko Kyiv Metropolitan University</institution>
          ,
          <addr-line>18/2 Bulvarno-Kudryavska str., 04053 Kyiv</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>CPITS-II 2024: Workshop on Cybersecurity Providing in Information and Telecommunication Systems II</institution>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Lviv Polytechnic National University</institution>
          ,
          <addr-line>79013 Lviv</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
      </contrib-group>
      <fpage>60</fpage>
      <lpage>71</lpage>
      <abstract>
        <p>With the development of decentralized technologies and the increasing volume of data generated and processed, there is a challenge to ensure effective and secure information management, especially in the context of distributed systems. Traditional centralized databases increasingly demonstrate limitations in terms of scalability and fault tolerance. The paper proposes a comprehensive analysis of modern blockchain-based decentralized database technologies and examines the authentication and authorization methods used in them. The study covers seven leading systems: BigchainDB, GUN, OrbitDB, Bluzelle, Fluree, and Ties.DB, and Hyperledger Fabric. The problem statement includes current challenges in the field of decentralized data storage, such as ensuring a high level of security, scalability, and compliance with regulatory requirements. An important component of the paper is the analysis of recent research and publications, focused on the development of consensus algorithms, improvement of cryptographic methods, and integration of smart contracts into decentralized databases. Each system is examined in terms of its architecture, consensus mechanisms, and approaches to data management. The main objective of the study is to systematize and comparatively analyze existing decentralized database technologies, assess their efficiency and security, and identify promising directions for further development. Special attention is paid to security methods, particularly the use of public key cryptography, smart contracts, and distributed access control.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;data protection</kwd>
        <kwd>blockchain</kwd>
        <kwd>government registries</kwd>
        <kwd>transparency</kwd>
        <kwd>data security</kwd>
        <kwd>confidentiality</kwd>
        <kwd>smart contracts</kwd>
        <kwd>audit</kwd>
        <kwd>personal data</kwd>
        <kwd>mathematical model</kwd>
        <kwd>trust 1</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        The development of information technologies over the past
decades has led to exponential growth in the volume of data
generated, stored, and processed. Traditional centralized
database management systems, which have long dominated
the industry, are increasingly facing limitations in terms of
scalability, security, and fault tolerance. In this context,
decentralized databases (DDBs) based on blockchain
technology have emerged as a promising solution that
promises to overcome these limitations [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ].
      </p>
      <p>
        The concept of decentralized systems is not new. It dates
back to the early days of computer networks and distributed
systems development. However, the emergence of
blockchain technology in 2008, presented in the work of
Satoshi Nakamoto [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ], gave impetus to the development of
a new generation of decentralized data storage and
processing systems. As Zheng et al. (2017) [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ] point out,
blockchain offers an innovative approach to ensuring data
integrity and immutability in a distributed environment
without the need for a trusted third party.
      </p>
      <p>
        Blockchain-based decentralized databases offer several
unique advantages compared to traditional systems. They
provide enhanced security through cryptographic methods
of data protection, transparency of operations through
public access to transaction history, and resistance to
censorship due to the distributed nature of the system [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ].
In their comprehensive study, Dinh et al. (2018) [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] further
analyze these systems from a data processing perspective,
highlighting the unique challenges and opportunities that
arise when implementing blockchain technology in
database management. These characteristics make DDBs
particularly attractive for a wide range of applications, from
financial systems and electronic voting to supply chain
management and medical data storage.
      </p>
      <p>
        However, along with the advantages, decentralized
databases also bring new challenges, especially in the area
of user authentication and authorization. Traditional access
control methods developed for centralized systems [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] often
prove ineffective or impractical in the context of DDBs. The
absence of a central governing body requires new
approaches to user identification, data access management,
and ensuring information confidentiality.
      </p>
      <p>
        The importance of reliable authentication and
authorization methods in decentralized systems cannot be
overstated. They are fundamental to ensuring data security,
access control, and maintaining user trust in the system. In
0009-0000-7426-3696 (P. Petriv);
0000-0002-8461-8996 (I. Opirskyy);
0000-0001-7671-8287 (N. Mazur)
© 2024 Copyright for this paper by its authors. Use permitted under
Creative Commons License Attribution 4.0 International (CC BY 4.0).
an environment where cyber attacks are becoming
increasingly sophisticated and regulatory requirements for
data protection are becoming more stringent (for example,
GDPR in Europe) [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ], the development of effective
authentication and authorization mechanisms becomes a
critical task for the widespread adoption of decentralized
databases.
      </p>
      <p>
        In recent years, several innovative approaches to
solving these problems have emerged. They range from the
use of complex cryptographic protocols and smart contracts
to the implementation of decentralized identity
management systems (DID) [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. Each of these approaches
has its advantages and limitations, and the choice of a
specific solution often depends on the specific requirements
of the particular application.
      </p>
      <p>Problem formulation. Despite significant progress in
the development of decentralized databases, several
unresolved issues remain, especially in the context of
authentication and authorization. The key challenges are:




</p>
      <sec id="sec-1-1">
        <title>Ensuring a high level of security without excessively</title>
        <p>complicating the user experience.</p>
        <p>Developing scalable solutions capable of handling a
large number of users and transactions.</p>
        <p>Addressing data privacy issues in the context of the
transparent nature of blockchain systems.</p>
        <p>Ensuring compliance with regulatory requirements,
especially in the field of personal data protection.</p>
        <p>Integration with existing systems and infrastructures.</p>
        <p>These issues create an urgent need for a comprehensive
analysis of existing decentralized database technologies and
the authentication/authorization methods used in them.</p>
        <p>
          Recent research and publications analysis.
Research in the field of decentralized databases and
authentication/authorization methods is actively
developing. Dinh et al. conducted a comprehensive review
of blockchain database systems [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ], analyzing their
architectures and consensus mechanisms. This work laid
the foundation for understanding the basic principles of
DDB functioning.
        </p>
        <p>
          Wang et al. focused on the issues of scalability and
performance of DDBs [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ], proposing new algorithms for
optimizing transaction processing. Their research
emphasizes the importance of efficient data processing in
distributed systems.
        </p>
        <p>
          In the area of security and privacy, Zhang et al.
proposed an innovative approach to ensuring data
confidentiality [
          <xref ref-type="bibr" rid="ref7">7</xref>
          ] in blockchain systems using
homomorphic encryption. This work opens up new
possibilities for protecting sensitive data in a decentralized
environment.
        </p>
        <p>
          Li et al. developed a new smart contract-based identity
management method [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] for blockchain systems,
demonstrating the potential for integrating complex
authorization logic directly into the blockchain.
        </p>
        <p>Xu et al. proposed a distributed authentication scheme
for the Internet of Things (IoT) based on blockchain,
highlighting the importance of adapting authentication
methods to the specific needs of different application
domains.</p>
        <p>
          Yevseiev et al. [
          <xref ref-type="bibr" rid="ref8">8</xref>
          ] presented a comprehensive analysis of
security models for socio-cyber-physical systems, which is
particularly relevant in the context of developing
decentralized databases and their integration with IoT and
other modern technologies. Balatska et al. [
          <xref ref-type="bibr" rid="ref9">9</xref>
          ] explored the
concept of applying blockchain in the context of Single
Sign-On (SSO) technology, opening new perspectives for
improving the security and convenience of authentication
in decentralized systems. Poberezhnyk et al. [
          <xref ref-type="bibr" rid="ref10">10</xref>
          ] proposed
a concept for a learning management system based on
blockchain technology, demonstrating the potential of
decentralized databases in the educational sphere.
        </p>
        <p>The purpose of the paper. The purpose of this paper
is to conduct a comprehensive analysis of modern
decentralized database technologies and the
authentication/authorization methods used in them. The
research is focused on:



</p>
      </sec>
      <sec id="sec-1-2">
        <title>Systematization and comparative analysis of</title>
        <p>architectures and functionalities of leading DDB
systems, such as BigchainDB, GUN, OrbitDB,
Bluzelle, Fluree, and Ties.DB, and Hyperledger Fabric.
Evaluation of the effectiveness and security of
various authentication and authorization methods in
a decentralized environment.</p>
        <p>Identification of key problems and limitations of
existing approaches to ensuring security in DDBs.</p>
        <p>Determination of promising directions for further
research and development in the field of DDB
security.</p>
        <p>The results of this study aim to provide developers,
researchers, and organizations with valuable information
for decision-making regarding the selection and
implementation of decentralized data management systems,
as well as to outline ways to improve security methods in
these systems.</p>
        <p>This work is particularly relevant in the context of
growing interest in decentralized technologies across
various sectors, from finance and healthcare to public
administration and the Internet of Things. Understanding
the strengths and weaknesses of different approaches to
authentication and authorization in decentralized systems is
critical for developing secure, efficient, and scalable
solutions capable of meeting the needs of the modern digital
world.</p>
      </sec>
    </sec>
    <sec id="sec-2">
      <title>2. Overview of decentralized database technologies</title>
      <p>Decentralized databases (DDBs) represent a new generation
of data storage and processing systems that combine the
principles of distributed systems with blockchain
technology. Unlike traditional centralized databases, DDBs
distribute data across multiple nodes, ensuring high fault
tolerance, transparency, and protection against
unauthorized changes.</p>
      <p>In this section, we will conduct a detailed analysis of
seven leading decentralized database technologies:
BigchainDB, GUN, OrbitDB, Bluzelle, Fluree, and Ties.DB,
and Hyperledger Fabric. Each of these systems offers a
unique approach to solving key problems of decentralized
data storage, in particular:</p>
      <sec id="sec-2-1">
        <title>Architecture and data model: We will examine how each system structures and organizes data, including the use of blockchain, graph models, or other approaches.</title>
        <p>Consensus mechanisms: We will analyze the
methods used to achieve agreement between
network nodes regarding the state of data.
Scalability and performance: We will assess each
system’s ability to handle large volumes of data
and transactions.</p>
        <p>Identification and authorization methods: Special
attention will be paid to mechanisms that ensure
secure user identification and control of data
access. This includes:</p>
      </sec>
      <sec id="sec-2-2">
        <title>Cryptographic methods used for identity creation</title>
        <p>and verification.</p>
        <p>Key and certificate management systems.</p>
        <p>Access control mechanisms at the data and
transaction levels.</p>
        <p>Implementation of smart contracts for automating
access rules.</p>
      </sec>
      <sec id="sec-2-3">
        <title>Integration and compatibility: We will consider</title>
        <p>how easily each system can be integrated with
existing technologies and standards.</p>
        <p>Privacy and confidentiality: We will analyze the
methods used to protect sensitive data in a
distributed environment.</p>
        <p>This comprehensive review will allow us not only to
understand the technical features of each system but also to
assess their suitability for various use cases, from financial
applications to supply chain management systems and the
IoT.</p>
        <p>Furthermore, we will pay attention to the challenges
and limitations faced by each technology, which will help
identify directions for further research and development in
the field of decentralized databases.</p>
        <sec id="sec-2-3-1">
          <title>2.1. BigchainDB</title>
          <p>
            BigchainDB is a decentralized database that combines the
properties of traditional databases with blockchain
characteristics, providing high throughput and low latency
[
            <xref ref-type="bibr" rid="ref11">11</xref>
            ].
          </p>
          <p>Architecture and data model. BigchainDB uses a
transaction-based data model, where each transaction
contains metadata, digital assets, and ownership transfer
information. The system organizes data into “blocks” that
are linked in a chain, forming a blockchain. This hybrid
architecture allows BigchainDB to retain the advantages of
both traditional databases and blockchain systems.</p>
          <p>
            Consensus mechanism. BigchainDB uses the Tendermint
consensus algorithm [
            <xref ref-type="bibr" rid="ref11">11</xref>
            ], which ensures rapid agreement
between network nodes. This mechanism allows the system
to achieve transaction finality within seconds, significantly
faster than traditional blockchain systems. Tendermint also
provides resistance to Byzantine failures, enhancing system
reliability.
          </p>
          <p>Scalability and performance. Performance evaluation of
BigchainDB showed that the system is capable of processing
thousands of transactions per second, bringing it close to
the performance of traditional databases. Scalability is
achieved through horizontal scaling of network nodes.
However, as the number of nodes increases, the complexity
of achieving consensus may grow.</p>
          <p>According to research by McConaghy et al. (2016),
BigchainDB demonstrates the ability to process up to 1
million records per second using a cluster of 32 nodes. This
significantly exceeds the performance of traditional
blockchain systems such as Bitcoin (7 transactions per
second) or Ethereum (15 transactions per second).</p>
          <p>Identification and authorization method. BigchainDB
uses public key cryptography for user identification. Each
user has a pair of keys: public (for identification) and private
(for signing transactions). Authorization is based on the
concept of “Proof of Asset Ownership”. Transactions are
signed with the owner’s private key, ensuring action
authorization. This approach provides a high level of
security but may create challenges in managing a large
number of keys in corporate environments.</p>
          <p>Integration and compatibility. BigchainDB provides an
API for integration with other systems, facilitating its
implementation into existing infrastructures. However, full
compatibility with traditional SQL databases is limited due
to its specific data model.</p>
          <p>Privacy and confidentiality. BigchainDB ensures
transaction transparency, which can be an advantage for
some use cases but creates challenges for maintaining the
confidentiality of sensitive data. The system offers limited
built-in data encryption mechanisms at the transaction
level.</p>
          <p>
            In summary, BigchainDB offers a unique combination
of high performance of traditional databases with the
security and immutability of blockchain. However, the
balance between transparency and confidentiality remains
a challenge for widespread implementation in scenarios
requiring a high level of data privacy.
2.2. GUN
GUN is an open-source decentralized graph database that
provides real-time data replication and supports an
offlinefirst architecture. According to Nadal (2018) [
            <xref ref-type="bibr" rid="ref12">12</xref>
            ], the creator
of GUN, this system was designed to be a decentralized
alternative to traditional databases, offering features such as
real-time synchronization, offline-first capabilities, and
graph-based data modeling.
          </p>
          <p>Architecture and data model. GUN uses a graph data
model where each node can have connections with other
nodes. This model provides flexibility in representing
complex relationships between data. GUN’s architecture is
based on the peer-to-peer principle, where each node can
act as both client and server simultaneously. This allows the
system to operate even with partial network connection
loss.</p>
          <p>
            Consensus mechanism. GUN uses a Conflict-free
Replicated Data Type (CRDT) mechanism [
            <xref ref-type="bibr" rid="ref12">12</xref>
            ] to achieve
consensus. This approach allows the system to effectively
resolve conflicts during simultaneous data updates by
different nodes, ensuring eventual consistency. CRDT
enables GUN to maintain high data availability even under
unstable network conditions.
          </p>
          <p>Scalability and performance. Performance evaluation of
GUN has shown that the system is capable of processing a
large number of read and write operations in real time.
Scalability is achieved through a decentralized architecture
where each node can independently process requests.
However, as the number of connections between data
increases, there may be delays in processing complex
queries.</p>
          <p>Identification and authorization method. GUN uses a key
pair-based identification system known as SEA (Security,
Encryption, Authorization). It supports decentralized
authentication without the need for a centralized server.
Users create and manage their keys locally. The concept of
a “trust graph” is implemented for access management
between nodes. This approach provides a high level of
privacy and control for users but may create difficulties in
implementing centralized security policies in corporate
environments.</p>
          <p>Integration and compatibility. GUN provides an API for
JavaScript, which facilitates integration with web
applications and Node.js projects. However, support for
other programming languages is limited, which may
complicate integration into some existing systems.</p>
          <p>Privacy and confidentiality. GUN ensures a high level of
privacy through local key storage and the ability to encrypt
data on the client side. However, full decentralization may
create challenges for implementing complex access control
and audit schemes in corporate environments.</p>
          <p>GUN stands out for its ability to provide high data
availability and offline operation, making it attractive for
distributed and mobile applications. However, limited
support for programming languages and the complexity of
implementing centralized security policies may limit its
application in some corporate scenarios.</p>
        </sec>
        <sec id="sec-2-3-2">
          <title>2.3. OrbitDB</title>
          <p>
            OrbitDB is a distributed database built on the InterPlanetary
File System (IPFS), providing decentralized data storage and
synchronization. Haad and Naevdal (2019) [
            <xref ref-type="bibr" rid="ref13">13</xref>
            ], the creators
of OrbitDB, describe it as a peer-to-peer database
specifically designed for the decentralized web. They
emphasize its ability to operate without centralized servers,
making it particularly suitable for decentralized
applications (dApps) and distributed systems that require
robust data management capabilities.
          </p>
          <p>Architecture and data model. OrbitDB uses IPFS for data
storage, ensuring high scalability and resistance to
censorship. The system supports various types of data
stores, including key-value stores, event logs, and document
databases. This flexible architecture allows OrbitDB to
adapt to diverse usage scenarios.</p>
          <p>
            Consensus mechanism. OrbitDB uses a Conflict-free
Replicated Data Type (CRDT) based consensus mechanism
[
            <xref ref-type="bibr" rid="ref13">13</xref>
            ], which effectively resolves conflicts during
simultaneous data updates by different nodes. This
approach ensures eventual data consistency without the
need for complex consensus algorithms.
          </p>
          <p>Scalability and performance. Evaluation has shown that
OrbitDB can scale effectively thanks to its use of IPFS.
However, performance may vary depending on the size of
the IPFS network and the type of operations. The system is
particularly effective for applications requiring high data
availability and resilience to network failures.</p>
          <p>Identification and authorization method. OrbitDB uses
IPFS identifiers for unique user identification. The system
supports distributed access control, where each database
has its own set of access rights. Elliptic curve
cryptographybased signatures are used to verify user actions. This
approach provides flexible access control but may
complicate management in large organizations.</p>
          <p>Integration and compatibility. OrbitDB provides a
JavaScript API, facilitating integration with web
applications. However, support for other programming
languages is limited, which may create challenges when
integrating with diverse systems.</p>
          <p>Privacy and confidentiality. OrbitDB provides a basic
level of privacy through access control but lacks built-in
data encryption mechanisms. This may require additional
measures to ensure the confidentiality of sensitive
information.</p>
          <p>OrbitDB stands out for its integration with IPFS, making
it attractive for decentralized web applications. However,
limited built-in encryption mechanisms and dependence on
the JavaScript ecosystem may restrict its application in
some scenarios.</p>
        </sec>
        <sec id="sec-2-3-3">
          <title>2.4. Bluzelle</title>
          <p>
            Bluzelle is a decentralized database that uses a ‘swarm’
model for data storage and management, providing high
scalability and reliability. According to the Bluzelle
Networks whitepaper (2017) [
            <xref ref-type="bibr" rid="ref14">14</xref>
            ], Bluzelle was specifically
designed as a decentralized database service for
decentralized applications (dApps). The whitepaper
emphasizes Bluzelle’s unique ‘swarm’ architecture, which
enables the network to dynamically scale and self-heal,
providing robust data storage solutions for
blockchainbased applications and other decentralized systems.
          </p>
          <p>Architecture and data model. Bluzelle uses a distributed
architecture where data is distributed among many nodes in
a ‘swarm’. This ensures high availability and fault tolerance.
The system implements a NoSQL data model, allowing
flexible storage and retrieval of data with various structures.</p>
          <p>
            Consensus mechanism. The system uses its consensus
algorithm based on the concept of ‘Proof of Stake’ [
            <xref ref-type="bibr" rid="ref14">14</xref>
            ],
which enables rapid agreement between nodes. This
mechanism allows Bluzelle to achieve high throughput
while maintaining the decentralized nature of the system.
          </p>
          <p>Scalability and performance. Evaluation has shown that
Bluzelle’s architecture allows for efficient scaling, and
processing of a large number of parallel queries. The system
uses dynamic sharding for load distribution, which
maintains high performance as data volume increases.</p>
          <p>Identification and authorization method. Bluzelle uses
cryptographic tokens for access control and employs smart
contracts to manage access rights. The system supports
multi-level authorization for different types of operations.
This approach provides flexible access control but may
require additional effort to integrate with existing
identification systems.</p>
          <p>Integration and compatibility. Bluzelle provides APIs for
various programming languages, facilitating integration
with different types of applications. The system also
supports standard data exchange protocols, simplifying
interaction with existing infrastructures.</p>
          <p>Privacy and confidentiality. Bluzelle offers basic data
encryption mechanisms, but full confidentiality can be
challenging in a distributed environment. The system
allows for configuring privacy levels for different types of
data.</p>
          <p>Bluzelle stands out for its ability to provide high
scalability and reliability thanks to its ‘swarm’ architecture.
However, implementing complex access control schemes
and ensuring full data confidentiality may require
additional efforts when deploying in corporate
environments.</p>
        </sec>
        <sec id="sec-2-3-4">
          <title>2.5. Fluree</title>
          <p>
            Fluree is a semantic graph database on blockchain that
supports smart contracts and provides high query
performance. Platz and Hilger (2019) [
            <xref ref-type="bibr" rid="ref15">15</xref>
            ], the creators of
Fluree, describe it as a practical decentralized database that
combines the benefits of blockchain technology with the
flexibility of semantic graph databases. They emphasize
Fluree’s unique approach to data management, which
includes time-travel queries, blockchain-grade security, and
the ability to run complex analytical queries directly on
blockchain data. This design, according to the authors,
makes Fluree particularly suitable for enterprise
applications that require both the immutability of
blockchain and the advanced querying capabilities of
traditional databases.
          </p>
          <p>Architecture and data model. Fluree uses a semantic
graph data model, allowing the creation of complex
relationships between data. The system integrates
blockchain to ensure the immutability and transparency of
transactions. This hybrid architecture enables Fluree to
combine the advantages of graph databases and blockchain.</p>
          <p>
            Consensus mechanism. Fluree uses its consensus
mechanism [
            <xref ref-type="bibr" rid="ref15">15</xref>
            ], which combines elements of Proof of Stake
and Byzantine fault tolerance. This allows the system to
achieve rapid consensus while maintaining a high level of
security and decentralization.
          </p>
          <p>Scalability and performance. Evaluation has shown that
Fluree provides high query performance thanks to its
optimized graph data structure. Scalability is achieved
through the ability to create private subnets. The system
also supports parallel query processing, which increases
overall performance.</p>
          <p>Identification and authorization method. Fluree uses
digital signatures based on elliptic curve cryptography for
identification. The system supports complex authorization
rules at the data level through smart functions, allowing
access rules to be defined at the level of individual
predicates. This provides high flexibility in configuring
access rights but may require careful planning during
implementation.</p>
          <p>Integration and compatibility. Fluree provides a RESTful
API and GraphQL interface, facilitating integration with
various types of applications. The system also supports
standard data formats, simplifying information exchange
with other systems.</p>
          <p>Privacy and confidentiality. Fluree offers flexible access
control mechanisms, but full data confidentiality can be
challenging due to the transparency of the blockchain. The
system allows configuring different levels of data visibility
for different users.</p>
          <p>
            Fluree stands out for its ability to combine semantic
queries with blockchain security, making it attractive for
applications that require complex data processing and high
levels of auditing. However, balancing blockchain
transparency with confidentiality requirements can be
challenging in some use cases.
2.6. Ties.DB
Ties.DB is an open-source decentralized SQL-like database
that provides flexibility in querying and data indexing.
According to the Ties.Network whitepaper (2017) [
            <xref ref-type="bibr" rid="ref16">16</xref>
            ],
Ties.DB was designed as a distributed database solution that
combines the familiarity of SQL with the benefits of
decentralization. The whitepaper emphasizes Ties.DB’s
unique approach to decentralized data management,
includes support for complex SQL-like queries, a tokenized
economic model for incentivizing network participants, and
a flexible architecture that allows for custom
implementation of consensus mechanisms. These features,
as described by Ties.Network, make Ties.DB particularly
suitable for decentralized applications that require
sophisticated data querying capabilities while maintaining
the benefits of blockchain-based data integrity and
distribution.
          </p>
          <p>Architecture and data model. Ties.DB uses a distributed
architecture with support for SQL-like queries. The system
provides a relational data model in a decentralized
environment. This architecture allows combining a familiar
SQL interface with the advantages of decentralized systems.</p>
          <p>
            Consensus mechanism. Ties.DB uses a Proof of
Stakebased consensus mechanism [
            <xref ref-type="bibr" rid="ref16">16</xref>
            ] for validating transactions
and data changes. This ensures efficient agreement between
network nodes while maintaining the decentralized nature
of the system.
          </p>
          <p>Scalability and performance. Evaluation has shown that
Ties.DB provides good scalability thanks to its distributed
architecture. The system is optimized for fast execution of
complex queries. The use of indexing and caching allows
maintaining high performance when working with large
volumes of data.</p>
          <p>Identification and authorization method. Ties.DB uses
cryptographic keys for user identification. The system
supports a tokenized model for access management and
service payments. Data owners can set flexible access rules
for their tables and records. This approach provides high
flexibility but may require additional efforts to integrate
with existing identification systems.</p>
          <p>Integration and compatibility. Ties.DB provides an
SQLlike interface, facilitating integration with existing systems
and applications. This allows developers to use familiar
tools and methods for working with data in a decentralized
environment.</p>
          <p>Privacy and confidentiality. Ties.DB offers basic mechanisms
for ensuring data privacy, but full confidentiality can be
challenging in a decentralized environment. The system
allows configuring access rights at the level of individual
tables and records.</p>
          <p>Ties.DB stands out for its ability to provide an SQL-like
interface in a decentralized environment, making it
attractive to organizations looking to transition to
decentralized systems while maintaining familiar
datahandling tools. However, ensuring full confidentiality and
compliance with regulatory requirements may require
additional measures.</p>
        </sec>
        <sec id="sec-2-3-5">
          <title>2.7. Hyperledger Fabric</title>
          <p>
            Hyperledger Fabric is a platform for creating private
blockchain networks with the ability to store data and
execute smart contracts, designed for enterprise use [
            <xref ref-type="bibr" rid="ref17">17</xref>
            ].
          </p>
          <p>Architecture and data model. Hyperledger Fabric uses a
modular architecture that allows customization of various
system components. The platform supports different data
models through the concept of ‘world state’. This flexible
architecture allows adapting the system to diverse business
requirements.</p>
          <p>
            Consensus mechanism. Hyperledger Fabric offers a
flexible approach to consensus [
            <xref ref-type="bibr" rid="ref17">17</xref>
            ], allowing the selection
of different algorithms depending on the needs of a specific
network. This can include algorithms based on Practical
Byzantine Fault Tolerance (PBFT) or Raft. Such flexibility
allows for optimizing network performance and security
according to specific requirements.
          </p>
          <p>Scalability and performance. Evaluation has shown that
Hyperledger Fabric provides high-performance thanks to an
architecture that separates tasks between different types of
nodes. Scalability is achieved through the ability to create
separate channels for different groups of participants. The
system also supports parallel execution of transactions,
which increases overall throughput.</p>
          <p>Research by Androulaki et al. (2018) showed that
Hyperledger Fabric can achieve a throughput of over 3500
transactions per second with a latency of less than a second
in a network of 100 nodes. The system demonstrates linear
scaling as the number of nodes increases.</p>
          <p>Identification and authorization method. Hyperledger
Fabric uses X.509 certificates to identify network
participants. The system supports a role-based membership
model (Membership Service Provider, MSP) and allows
configuring complex authorization rules through the
endorsement policies system. This approach provides a high
level of control and flexibility in access management, which
is especially important for enterprise applications.</p>
          <p>Integration and compatibility. Hyperledger Fabric
provides SDKs for various programming languages,
facilitating integration with enterprise systems. The
platform also supports standard data exchange protocols
and can be integrated with existing identity and access
management systems. This makes Fabric particularly
attractive to organizations looking to implement blockchain
technologies into their existing IT infrastructure.</p>
          <p>Privacy and confidentiality. Hyperledger Fabric offers
advanced privacy features, including private channels and
private data. This allows the creation of subnets with limited
access and the storing of sensitive information visible only
to authorized participants. Additionally, the platform
supports the use of Zero-Knowledge Proofs for additional
privacy protection.</p>
          <p>Hyperledger Fabric stands out for its focus on enterprise
needs, offering a high level of customization, performance,
and privacy. The platform is particularly suitable for
creating consortium blockchains where control over
network participants and their rights is required. However,
the complexity of setting up and managing such a system
may require significant resources and expertise.</p>
          <p>Overall, Hyperledger Fabric offers a powerful solution
for organizations seeking ways to implement blockchain
technologies while meeting corporate requirements for
security, performance, and confidentiality. Its modular
architecture and flexibility in configuration allow adapting
the platform to a wide range of uses, from supply chain
management to financial services and healthcare.</p>
        </sec>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Comparative analysis of authentication and authorization methods</title>
      <p>The analysis of seven leading decentralized database
technologies revealed significant differences in approaches
to authentication and authorization. These differences
reflect the diversity of requirements and use cases for which
these systems were developed.</p>
      <sec id="sec-3-1">
        <title>3.1. Cryptographic methods</title>
        <p>All the systems examined are based on public key
cryptography but implement it differently. BigchainDB and
Hyperledger Fabric use traditional approaches with digital
signatures, providing a high level of security and
compatibility with existing standards. In contrast, GUN and
OrbitDB introduce innovative approaches such as SEA
(Security, Encryption, Authorization) and IPFS identifiers
respectively, allowing them to better adapt to the specific
requirements of decentralized systems.</p>
        <p>Particular attention should be paid to Fluree’s approach,
which uses smart functions to implement complex
authorization rules at the data level. This gives the system
unique flexibility in configuring access rights but may
complicate the security management process for less
experienced users.</p>
        <p>The analysis shows that the choice of cryptographic
method significantly affects the balance between security,
flexibility, and ease of use of the system. Systems with more
traditional approaches tend to integrate more easily with
existing infrastructures, while innovative solutions offer
new possibilities but may require additional staff training.</p>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Key management</title>
        <p>Key management approaches differ significantly between
systems, reflecting various philosophies regarding the
balance between security and usability. BigchainDB and
Ties.DB places the responsibility for key management on
users, which enhances security but can be challenging for
ordinary users. This approach may be optimal for systems
where users have a high level of technical literacy.
GUN offers decentralized key management, which improves
privacy but may complicate access recovery. This solution
is particularly interesting for applications where user
privacy is a top priority.</p>
        <p>Hyperledger Fabric uses centralized certification
services (CA), which facilitates management in corporate
environments but creates a single point of failure. This
approach reflects Fabric’s orientation towards enterprise
applications, where decentralized identity management is
the norm.</p>
        <p>The analysis shows that the choice of key management
approach should take into account the specifics of the target
audience and use cases. Systems aimed at mass users may
require simpler solutions, while enterprise applications may
prefer more controlled approaches.</p>
      </sec>
      <sec id="sec-3-3">
        <title>3.3. Granularity of access control</title>
        <p>The level of access control granularity varies from system
to system, affecting their suitability for different use cases.
Fluree and Hyperledger Fabric offer the most flexible
mechanisms, allowing access rules to be defined at the level
of individual data fields. This makes them particularly
attractive for scenarios requiring fine-grained control over
data access, such as in the financial sector or healthcare.</p>
        <p>BigchainDB and Bluzelle provide access control at the
transaction and asset level, which may be sufficient for
many business applications but less flexible compared to the
approach of Fluree and Fabric.</p>
        <p>GUN and OrbitDB have more limited capabilities, focusing
on access to nodes or databases as a whole. This may be
acceptable for simple applications or systems where speed
and simplicity are priorities, but it may limit their use in
complex corporate environments.</p>
        <p>The analysis shows that choosing a system with an
appropriate level of access control granularity is critical to
balancing security and data management efficiency.
Systems with more detailed access control typically require
more resources for setup and management but provide more
opportunities for regulatory compliance and protection of
sensitive data.</p>
      </sec>
      <sec id="sec-3-4">
        <title>3.4. Integration with existing authentication systems</title>
        <p>The integration of decentralized databases with existing
authentication systems is a critical aspect of their
implementation in organizational structures. Analysis of the
technologies examined revealed significant differences in
their integration capabilities, which substantially affect
their suitability for various environments.</p>
        <p>For effective integration, an identity and data
transformation model is proposed, which ensures a smooth
transition from traditional systems to decentralized
solutions. This model includes stages of input data
normalization, generation and validation of decentralized
identifiers (DIDs), processing in a distributed ledger, and
generation of output tokens for existing systems.
Hyperledger Fabric demonstrates the highest level of
integration capabilities due to its support for standard
protocols such as LDAP, OAuth 2.0, and Active Directory.
This allows effective interaction with existing corporate
identity management systems, simplifying the process of
input data normalization and identity transformation.</p>
        <p>BigchainDB and Ties.DB, offering APIs for integration,
occupies an intermediate position. While they provide some
flexibility, additional development may be needed to
achieve full compatibility. In the context of the proposed
model, this means creating specialized adapters for efficient
data processing and DID generation.</p>
        <p>GUN and OrbitDB have the most limited integration
capabilities, creating significant challenges when
implementing them in existing infrastructures. These
systems require the development of complex gateways or
intermediate services, which can negatively affect overall
efficiency and complicate scaling.</p>
        <p>Bluzelle and Fluree occupy an intermediate position,
offering a certain level of integration through APIs and
support for external services. This allows adapting them to
the proposed model with moderate effort.</p>
        <p>The effectiveness of integration significantly affects the
overall performance and scalability of the system. Using the
proposed mathematical model, integration efficiency (E) can
be expressed as a function of throughput (T), DID validation
speed (V), level of consensus between nodes (C), data
transformation delay (D), and network load (L):</p>
        <p>∙  ∙ 
 = .</p>
        <p>∙</p>
        <p>Additionally, the scalability coefficient (S) can be
represented as:</p>
        <p>∙ 
 =</p>
        <p>∙ 
where N is the number of nodes in the network, P is the
query processing performance per node, I is the complexity
of integrating a new node, and R is the resource
requirements per node.</p>
        <p>Systems with better integration capabilities, such as
Hyperledger Fabric, allow achieving higher E and S
indicators by reducing parameters D and I.</p>
        <p>Thus, choosing a system with appropriate integration
capabilities is a critical factor for the successful
implementation of decentralized databases. Systems with
developed integration capabilities provide a smoother
transition and reduce risks, especially in the context of large
organizations with complex existing infrastructures.</p>
      </sec>
      <sec id="sec-3-5">
        <title>3.5. Support for anonymity and pseudonymity</title>
        <p>Approaches to ensuring anonymity and pseudonymity
differ significantly among the systems examined, reflecting
different priorities regarding privacy and transparency.</p>
        <p>GUN and OrbitDB provide a high level of anonymity
due to their decentralized nature and the use of
pseudonyms. This makes them attractive for applications
where user privacy is a top priority, such as in social
networks or voting systems.</p>
        <p>BigchainDB and Bluzelle allow pseudonymous use but store
all transactions, which may allow behavior analysis. This
approach provides a balance between privacy and
auditability, which can be useful for financial applications
or supply chain management systems.</p>
        <p>Hyperledger Fabric, oriented towards enterprise use,
has limited possibilities for anonymity but offers private
channel features for confidentiality. This reflects the
priority of regulatory compliance and the need for auditing
in corporate environments.</p>
        <p>The analysis shows that the choice of a system with an
appropriate level of anonymity and pseudonymity support
depends on the specific requirements for privacy and
transparency within a particular application. Systems with
a high level of anonymity may be better for applications
focused on protecting user privacy, while systems with
greater transparency may be more suitable for corporate
and regulated environments.</p>
      </sec>
      <sec id="sec-3-6">
        <title>3.6. General conclusions of the comparative analysis</title>
        <p>The comparative analysis of authentication and
authorization methods in the examined decentralized
databases reveals a significant diversity of approaches, each
with its advantages and limitations.</p>
        <p>Systems oriented towards enterprise use, such as
Hyperledger Fabric, offer more traditional and integrated
approaches to authentication and authorization, facilitating
their implementation into existing business processes.
However, these systems may be less flexible in the context
of decentralization and anonymity.</p>
        <p>On the other hand, systems like GUN and OrbitDB offer
a high level of decentralization and anonymity but may
create challenges when integrating with traditional
corporate systems.</p>
        <p>BigchainDB, Bluzelle, Fluree, and Ties.DB occupy
intermediate positions, offering various combinations of
features that allow them to adapt to different usage
scenarios.</p>
        <p>The choice of an optimal system depends on the specific
requirements of the project, including the necessary level of
security, privacy, scalability, and integration with existing
systems. Organizations should carefully evaluate their
needs and constraints before choosing a specific
decentralized database technology.</p>
        <p>Authentication and authorization in decentralized
systems present a particular challenge due to the absence of
a central governing body. Traditional methods that rely on
centralized authentication servers cannot be directly
applied in such an environment. Instead, decentralized
databases must develop innovative approaches that ensure
reliable user identification and access control while
maintaining the advantages of a distributed architecture.</p>
        <p>These tables demonstrate the diversity of approaches to
authentication and authorization in decentralized databases,
highlighting the strengths and limitations of each system.</p>
      </sec>
      <sec id="sec-3-7">
        <title>3.7. Comparative tables</title>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Advancing decentralized database technologies</title>
      <p>
        Current research in the field of decentralized databases
(DDBs) reveals several key areas that require further
improvement and development. Analysis of these areas not
only outlines the current limitations of the technology but
also identifies promising ways to overcome them.
One of the most critical aspects of DDB development is
improving their scalability. Research by Bano et al. (2019)
[
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] demonstrates that existing consensus algorithms,
particularly Proof of Work, have significant limitations in
terms of throughput as the number of nodes in the network
increases. This leads to a decrease in transaction processing
speed and an increase in latency, which is especially critical
for applications in the financial sector and real-time
systems.
To address the scalability problem, new approaches are
being developed, among which the concept of sharding is
particularly noteworthy. Zamani et al. (2018) [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] propose a
method of dividing the network into subnets for parallel
transaction processing, which significantly increases the
system’s throughput without compromising security. This
approach opens up possibilities for creating
highperformance DDBs capable of competing with centralized
systems in terms of transaction processing speed.
      </p>
      <p>
        Another important aspect of DDB development is
improving data storage and processing methods. Sharma et
al. (2019) [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ] point to the problem of significant database
size increase when using traditional approaches to data
storage in blockchain. This complicates maintenance and
synchronization between nodes, especially for full nodes
that store the entire transaction history. This can result in a
decrease in the network’s decentralization level due to a
reduction in the number of participants capable of
maintaining full nodes.
      </p>
      <p>
        Ensuring data confidentiality in a distributed
environment remains one of the key challenges for DDBs.
Reid and Harrigan (2013) [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ] demonstrated the possibility
of analyzing links between transactions even in systems
considered anonymous, which can lead to user
deanonymization. This problem is particularly relevant for
applications requiring a high level of privacy, such as in
healthcare or financial services.
      </p>
      <p>
        A promising direction for solving the confidentiality
problem is the application of Zero-Knowledge Proofs (ZKP)
technology. Kosba et al. (2016) [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ] demonstrate the potential
of this technology for creating private smart contracts,
allowing transaction verification without disclosing their
content. This opens up new possibilities for ensuring
privacy in decentralized systems while maintaining their
main advantages.
      </p>
      <p>
        An important aspect of DDB development is also
ensuring compliance with regulatory requirements,
particularly the General Data Protection Regulation (GDPR)
in the European Union. Finck (2019) [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ] analyzes the
potential conflict between the right to be forgotten provided
by GDPR and the immutability of data in blockchain. This
problem requires the development of innovative technical
solutions that will allow modifying or deleting data without
compromising blockchain integrity.
      </p>
      <p>
        Given the development of quantum computing, the
development and implementation of quantum-resistant
cryptography algorithms become particularly relevant.
Bernstein and Lange (2017) [
        <xref ref-type="bibr" rid="ref23">23</xref>
        ] propose some
postquantum cryptographic primitives that can ensure DDB
security even in the era of quantum computers. This is
critical for ensuring the long-term viability and reliability of
decentralized systems.
      </p>
      <p>
        The development of quantum-resistant cryptography is
crucial for the long-term security of decentralized
databases. Horpenyuk et al. [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ] argue that the
implementation of post-quantum cryptographic algorithms
is not just a future concern, but a present necessity. They
emphasize that the transition to post-quantum
cryptography should be gradual and well-planned,
involving the coexistence of classical and post-quantum
algorithms during the transition period. This approach
ensures the continuity of security measures while adapting
to emerging quantum threats. The authors also highlight the
importance of standardizing post-quantum algorithms,
which is crucial for their widespread adoption in
decentralized systems [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ]. This research provides valuable
insights for developing robust security strategies for
decentralized databases in the face of advancing quantum
computing technologies.
      </p>
      <p>
        Research by Deineka et al. [
        <xref ref-type="bibr" rid="ref25">25</xref>
        ] on designing data
classification and secure store policy according to SOC 2
Type II provides valuable insights into ensuring regulatory
compliance and data security in decentralized systems. This
work is particularly relevant for DDBs that need to meet
stringent security and privacy standards.
      </p>
      <p>
        The development of decentralized identification
systems (DID) and the concept of self-sovereign identity,
described by Allen (2016) [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ], opens new perspectives for
improving identity management in DDBs. These
approaches allow users to have full control over their
identification data, which is an important step towards
enhancing privacy and security.
      </p>
      <p>
        An important direction of development is ensuring
cross-blockchain interaction. Projects such as Polkadot,
proposed by Wood (2016) [
        <xref ref-type="bibr" rid="ref26">26</xref>
        ], aim to create an
infrastructure for effective communication between
different blockchain systems. This can significantly expand
the capabilities and application areas of decentralized
systems, creating a single global ecosystem.
      </p>
      <p>
        Recent research has also explored the application of
decentralized database technologies in specific domains,
demonstrating their versatility and potential for innovation.
Balatska et al. [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] propose a concept for applying blockchain
technology in the context of Single Sign-On (SSO) systems.
Their work suggests that integrating blockchain with SSO
can enhance security and user authentication processes,
potentially revolutionizing access management in
decentralized environments. This approach could be
particularly beneficial for DDBs that require robust and
secure authentication mechanisms.
      </p>
      <p>
        Furthermore, Poberezhnyk et al. [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ] have developed a
concept for a learning management system based on
blockchain technology. Their research illustrates how DDBs
can be effectively utilized in educational settings, offering
improved data integrity, transparent record-keeping, and
enhanced security for student information. This application
of blockchain in education demonstrates the potential of
decentralized databases to transform traditional systems
across various sectors, providing new solutions to
longstanding challenges in data management and security.
      </p>
      <p>
        Martseniuk et al. [
        <xref ref-type="bibr" rid="ref27">27</xref>
        ] propose an automated conformity
verification concept for cloud security, which can be
adapted for use in decentralized database environments to
enhance security measures and ensure compliance with
various standards.
      </p>
      <p>
        Additionally, research by Yevseiev et al. (2023) [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ] on
security models of socio-cyber-physical systems emphasizes
the importance of integrating DDBs with other modern
technologies. Balatska et al. (2024) [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] consider the concept
of blockchain application in the context of Single Sign-On
(SSO) technology, opening new perspectives for improving
the security and convenience of authentication in
decentralized systems. Poberezhnyk et al. (2023) [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ]
demonstrate the potential of DDBs in the educational
sphere, proposing a concept of a learning management
system based on blockchain technology.
      </p>
      <p>In summary, it can be stated that decentralized database
technologies have significant potential for further
development and improvement. Addressing current
challenges in the areas of scalability, confidentiality,
regulatory compliance, and security paves the way for
creating a new generation of distributed systems capable of
meeting the growing needs of the modern digital world.
Further research and innovation in this field are critical for
realizing the full potential of decentralized technologies and
their widespread implementation in various spheres of
human activity.</p>
    </sec>
    <sec id="sec-5">
      <title>5. Conclusions</title>
      <p>The research emphasizes that blockchain-based
decentralized databases, due to their distributed nature, can
solve problems associated with centralized data storage and
management systems. This allows avoiding a single point of
failure and contributes to a higher level of user information
protection.</p>
      <p>The main aspect of the study lies in the careful
examination and comparison of the advantages of various
DDB technologies, such as BigchainDB, GUN, OrbitDB,
Bluzelle, Fluree, and Ties.DB, and Hyperledger Fabric. The
results show that these systems not only provide a high
level of security but also contribute to solving problems of
scalability, confidentiality, and access management.</p>
      <p>The technical aspects of implementing authentication
and authorization methods in DDBs are examined in detail,
including the use of public key cryptography, smart
contracts, and distributed access control. This can
significantly increase the reliability of user identification
processes and access rights management.</p>
      <p>The results of the DDB technology analysis show that,
despite their advantages in ensuring data transparency and
immutability, there are problems related to scalability and
compliance with regulatory requirements. The use of
innovative approaches, such as sharding and
ZeroKnowledge Proofs, can help solve these issues, providing an
efficient and confidential data processing mechanism.</p>
      <p>Additionally, it is important to note that DDBs can
become a fundamental element in solving interoperability
problems that often arise in traditional database systems.
Their ability to provide a unified and reliable record of
information can contribute to creating global data
ecosystems without the risk of security breaches.</p>
      <p>In the context of DDB development, it is important to
consider collaboration between developers of different
systems to ensure standardization and interaction between
various platforms and protocols, especially in the field of
cross-blockchain interaction.</p>
    </sec>
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