Towards a Trustworthy Rental Market: A Blockchain-Based Housing System Architecture

Abstract

This study explores the transformative potential of blockchain technology in overhauling conventional housing rental systems. It specifically addresses persistent issues, such as information asymmetry, fraudulent listings, weak Rental Agreements, and data breaches. A comprehensive review of ten academic publications highlights the architectural frameworks, underlying technologies, and myriad benefits of decentralized rental platforms. The intrinsic characteristics of blockchain—immutability, transparency, and decentralization—are pivotal in enhancing the credibility of rental information and proactively preventing fraudulent activities. Smart contracts emerge as a key innovation, enabling the automated execution of Rental Agreements, thereby significantly boosting efficiency and minimizing reliance on intermediaries. Furthermore, Decentralized Identity (DID) solutions offer a robust mechanism for securely managing identities, effectively mitigating risks associated with data leakage, and fostering a more trustworthy environment. The suitability of platforms such as Hyperledger Fabric for developing such sophisticated rental systems is also critically evaluated. Blockchain-based systems promise to dramatically increase market transparency, bolster transaction security, and enhance fraud prevention. They also offer streamlined processes for dispute resolution. Despite these significant advantages, the widespread adoption of blockchain in the rental sector faces several challenges. These include inherent technological complexity, adoption barriers, the need for extensive legal and regulatory adaptation, and critical privacy concerns (e.g., ensuring compliance with GDPR). Furthermore, blockchain scalability limitations and the intricate balance between data immutability and the necessity for occasional data corrections present considerable hurdles. Future research should focus on developing user-friendly DID solutions, enhancing blockchain performance and cost-efficiency, strengthening smart contract security, optimizing the overall user experience, and exploring seamless integration with emerging technologies. While current challenges are undeniable, blockchain technology offers a powerful suite of tools for fundamentally improving the rental market’s efficiency, transparency, and security, exhibiting significant potential to reshape the entire rental ecosystem.

1. Introduction

1.1. Research Background and Motivation

The rapid confluence of global population growth and accelerating urbanization has resulted in a persistent surge in demand for rental housing worldwide. However, this escalating demand continues to confront myriad systemic challenges inherent in traditional rental models. These pervasive issues include information asymmetry, the proliferation of fraudulent listings, a lack of robust legal protection within lease agreements, and the ever-present risk of personal data breaches. Collectively, these deficiencies significantly undermine the rights and interests of tenants and landlords, thereby impeding the healthy and sustainable development of the rental market.

In Taiwan, these challenges are particularly salient. Tenants frequently navigate a landscape dominated by privately posted rental listings, which are often unverified, contributing to widespread misinformation and a high incidence of deceptive practices. Unscrupulous landlords exploit these vulnerabilities, engaging in illicit activities such as the fraudulent seizure of deposits or the theft of personal information, thereby directly infringing upon tenant rights. Conversely, landlords encounter considerable difficulties in accurately verifying tenant identities and assessing their financial credibility, which elevates the risk of leasing to unreliable individuals. The reliance on manual processes for collecting and verifying sensitive documents, such as income statements or employment records, not only introduces significant inefficiencies but also inherently exposes critical personal data to the heightened risks of leakage or misuse.

Moreover, lease agreements in Taiwan frequently suffer from a lack of legal enforceability. Many contracts do not meet legal standards or clearly define responsibilities, making it challenging for tenants to protect their rights during disputes. Although the government has implemented reforms such as actual price registration and lease management policies, data from the Ministry of the Interior (MOI) [1] and the 2020 National Housing Census [2] reveal persistent market disparities. By the end of 2023, only 687,000 valid rental contracts were officially recorded, yet census data indicate that over 2.45 million people reside in rental properties. This significant discrepancy highlights the prevalence of an underground rental economy. These problems can be summarized into four key issues: unverified listings, lack of market transparency, weak contract protection, and personal data vulnerability. To address these multifaceted challenges, this study explores the potential use of blockchain technology as a novel solution.

1.2. Research Objectives and Questions

This study aims to leverage blockchain technology to address the pervasive issues within the traditional rental market, particularly in the context of Taiwan. The primary objectives are to enhance transparency, improve security, and empower users by mitigating information asymmetry, reducing fraudulent activities, strengthening contract enforceability, and safeguarding personal data.

Based on these objectives, the following research questions will be addressed:

• How can blockchain technology, specifically through decentralization, transparency, immutability, and smart contracts, be effectively applied to overcome the challenges in traditional rental markets?
• What is the optimal architecture for a blockchain-based rental system that integrates trusted third-party verification and Decentralized Identity (DID) to ensure the legitimacy of listings and protect user privacy?
• How can smart contracts be designed and implemented to automate rental processes, including rent payments, deposit handling, and lease termination, thereby increasing efficiency and fairness while reducing reliance on intermediaries?
• To what extent can the proposed blockchain-based system enhance privacy protection and improve identity verification for both landlords and tenants, fostering greater trust within the rental ecosystem?

1.3. Research Scope and Limitations

This research focuses on proposing and evaluating a blockchain-based rental system designed to mitigate key challenges in the residential rental market. While the principles and proposed solutions are broadly applicable, this study specifically examines the context of the Taiwanese rental market due to its pronounced issues with unverified listings, limited transparency, weak contract protection, and data vulnerability.

The limitations of this study include the following:

• Implementation Complexity: While a system model is proposed, a full-scale, nationwide deployment and its long-term societal impact are beyond the scope of this study.
• Regulatory Environment: This study acknowledges the current regulatory landscape, but a detailed analysis of potential legal or policy hurdles for blockchain adoption in real estate is not the primary focus.
• User Adoption: This research does not delve deeply into the socio-economic factors influencing user adoption rates of a new blockchain-based platform.
• Technological Evolution: The rapid evolution of blockchain and related technologies means that the proposed solutions may require adaptation in the future.

1.4. Research Methodology

This study adopts a design science research methodology, focusing on the creation of an innovative artifact (the blockchain-based rental system) to solve identified real-world problems. The research process involves several stages:

• Problem Identification and Motivation: Detailed analysis of existing problems in the rental market, especially in Taiwan, including unverified listings, lack of transparency, weak contract protection, and data vulnerability, as outlined in Section 1.1.
• Objectives of a Solution: Defining the clear goals for the proposed system, such as enhancing security, transparency, and user empowerment.
• Design and Development: Proposing a novel rental platform architecture that integrates blockchain technology, Decentralized Identity (DID), and smart contracts. This includes conceptualizing the verifiable third-party mechanism.
• Demonstration: Illustrating the practical application of the proposed system through a detailed system model and, if feasible, a prototype implementation.
• Evaluation: Assessing the proposed system’s potential benefits in addressing the identified problems, focusing on aspects such as privacy protection, identity verification, automation, and cost reduction.
• Communication of Results: Presenting the findings, contributions, and implications for future research and development.

The methodology will involve a comprehensive literature review of blockchain applications in various sectors, Decentralized Identity systems, and smart contract functionalities, as well as an analysis of existing rental market obstacles in Taiwan.

1.5. Research Contributions

The main contributions of this study are as follows:

We propose an innovative rental platform architecture that integrates trusted third-party verification and Decentralized Identity to construct a more secure, transparent, and user-empowered ecosystem. This architecture offers a novel approach to addressing fundamental trust and information asymmetry issues in the rental market.

We emphasize the crucial role of Decentralized Identity (DID) in enhancing privacy protection, improving identity verification, and fostering trust between landlords and tenants. This highlights a pathway to empowering users with greater control over their data while enabling secure and verifiable interactions.

We demonstrate how smart contracts can automate rental processes and effectively reduce dependency on intermediaries, thereby lowering transaction costs and significantly increasing operational efficiency. This showcases the potential for a more streamlined, fair, and automated rental transaction lifecycle.

1.6. Thesis Structure

Section 1: Introduction: This section provides the research background and motivation; outlines the research objectives and questions; defines the scope and limitations; details the methodology; and highlights the key contributions of this study.

Section 2: Literature Review: This section provides a comprehensive overview of the fundamental blockchain principles; its applications across diverse fields; and existing research specifically focusing on blockchain technology in housing rental systems, laying the groundwork for understanding relevant technologies.

Section 3: Proposed System Model: This section introduces the detailed design and conceptual framework of the blockchain-based rental system, including integrating trusted third-party verification, Decentralized Identity (DID), and smart contracts.

Section 4: System Implementation and Demonstration: This section describes the proposed system’s practical aspects and demonstrates its core functionalities.

Section 5: Evaluation Results: This section presents the findings from evaluating the proposed system, assessing its performance and effectiveness in addressing the identified challenges.

Section 6: Conclusions and Future Research: This section summarizes this study’s key findings, discusses its implications, and suggests future research and development directions in this area.

2. Related Research

This section explores the existing academic literature on the following research topic: “Blockchain-Based Rental Housing System.” It begins by outlining the fundamental principles of blockchain technology, providing a necessary conceptual foundation. Subsequently, it examines the current applications of blockchain across various fields, illustrating its versatility and transformative potential beyond its origins in cryptocurrency. This section then focuses on the latest developments and emerging trends, specifically in blockchain applications within rental housing management. Through a comprehensive review and critical analysis of these studies, we lay the theoretical foundation for the innovative blockchain-based rental system architecture proposed in the subsequent sections of this thesis. This structured review ensures that the proposed system is grounded in existing knowledge while identifying gaps that the current research seeks to address.

2.1. Fundamental Principles and Characteristics of Blockchain Technology

Blockchain technology is fundamentally a decentralized database [3] or Distributed Ledger Technology (DLT) [4]. It utilizes cryptographic principles [5] to bundle records of transactions occurring within a specific period into blocks. These blocks are then connected in chronological order [3] through a chain structure [6]. Each block contains transaction data and is tightly linked to the previous block via a cryptographic hash function [6], forming a tamper-resistant record [7].

The blockchain concept was first introduced by Satoshi Nakamoto in 2009 in the white paper “Bitcoin: A Peer-to-Peer Electronic Cash System” [8]. This publication proposed blockchain as the underlying technology for a decentralized digital currency system—Bitcoin [5]. Since then, blockchain technology has been applied across various fields, including vehicle transport, securities and finance, and healthcare. The emergence of private blockchains has also addressed practical industry needs, and blockchain applications are steadily maturing [3].

Blockchain technology possesses several key characteristics that enable its powerful potential across various sectors, helping to solve many issues faced by traditional systems [6]:

Decentralization: Blockchain does not rely on a centralized third-party authority. Instead of being stored on a central server, data is distributed across numerous nodes in the network [4]. Each node in this distributed network has equal rights and responsibilities [6], eliminating dependence on any single entity [3].

Immutability: Once a transaction is verified and recorded on the blockchain, it becomes a permanent part of the ledger [7]. Since blocks are connected via hash values, altering any block results in changes to the hash values of subsequent blocks [6]. Such modifications are complicated, as they require controlling more than 51% of the network nodes [6] or consensus from most of the network, significantly enhancing data security and integrity [7].

Transparency: Transaction records on public blockchains are generally open and viewable by participants in the network. This transparency helps build trust, accountability, and smooth operations, significantly reducing the risk of fraud and disputes [5]. Despite the high level of transparency, participant identities can be protected using cryptographic techniques. For example, zero-knowledge proofs can verify identity legitimacy without revealing actual identities [6].

Security: Blockchain employs cryptographic technologies such as hash algorithms and asymmetric encryption [6] to protect transaction data and user identities. Each block’s connection must be verified through a consensus mechanism to ensure data accuracy and validity [3], thereby safeguarding the network. Cryptographic assurance replaces the traditional trust-based model in the system [3].

Smart Contracts: The concept of smart contracts was first proposed by Nick Szabo in 1994. A smart contract is an event-driven program written in code that runs on the blockchain. Once predefined conditions are met, the smart contract automatically executes its terms without human intervention [3], improving transaction efficiency and trustworthiness. Blockchain provides a trustworthy environment for smart contracts to operate [3]. Compiling traditional Rental Agreements into smart contracts allows transactions to be executed automatically. Ethereum is a platform that supports the deployment and execution of smart contracts. These contracts are transparent, immutable, and publicly verifiable, enhancing the fairness of transactions.

2.2. Applications of Blockchain Technology Across Diverse Fields

With its unique characteristics, blockchain technology has gradually permeated various industries, demonstrating significant effectiveness in addressing traditional problems, enhancing efficiency, and establishing trust. This technology has already found robust applications across diverse sectors, including transportation, financial services, and healthcare [3], with its utility continuing to mature. Within decentralized networks, such as those enabled by blockchain, each node possesses equal rights and responsibilities, thereby effectively eliminating reliance on any single central entity. Furthermore, information on public blockchains is transparently accessible, allowing participants to view transaction records; this inherent openness fosters trust and accountability within the network. Blockchain primarily employs sophisticated cryptographic techniques, such as hash algorithms and asymmetric encryption, to secure both data and user identities. Through established consensus mechanisms, the accuracy and validity of information are continuously validated [8], fundamentally transforming traditional trust-based systems into environments secured by verifiable cryptographic guarantees.

Financial Sector: The earliest application of blockchain technology was in cryptocurrency, but its potential extends far beyond this initial use case. The financial sector has adopted blockchain for diverse applications, including cross-border payments, digital identity verification, supply chain finance, and securities trading. The primary objectives in these applications are to reduce transaction costs, improve transaction speed, and enhance transparency and security [5].

Supply Chain Management: Blockchain technology offers significant advancements in supply chain management by enabling the end-to-end traceability of products from their initial production stages through transportation and ultimately to sales. This inherent capability substantially increases visibility and transparency across the supply chain, which is crucial for combating counterfeit goods and improving overall operational efficiency. For example, a case study by Casado-Vara et al. [9] explored how blockchain can enhance the food supply chain [5,6], demonstrating its practical benefits in ensuring product integrity and fostering consumer trust.

Healthcare Sector: The healthcare sector presents vast potential for blockchain integration in areas such as Electronic Health Record (EHR) management, pharmaceutical traceability, clinical trial oversight, and secure personal health data sharing. As an illustrative example, Hsieh et al. [10] proposed physiological-chain [10], a privacy-preserving physiological data-sharing ecosystem built upon a dual-layer blockchain architecture. This innovative system includes a Decentralized Identity (DID) Chain and an Application Data (App) Chain, leveraging smart contracts to manage identity and access control in compliance with General Data Protection Regulation (GDPR) principles, thereby ensuring both data utility and patient privacy.

Land Management: Traditional land management systems frequently suffer from inefficiencies, a lack of transparency, and significant vulnerability to corruption and fraud. Due to its inherent characteristics of immutability, transparency [7], and security [11], blockchain technology is regarded as a powerful tool for reforming land administration. It can enhance land transactions’ efficiency and security, prevent double-spending and fraudulent activities, and ultimately strengthen public trust in land records. For instance, Junaid et al. [7] proposed a secure blockchain-based land registry framework. Countries such as Estonia and Georgia have begun exploring and implementing blockchain-based land registration projects. Furthermore, the authors of [7] introduced a blockchain-enabled framework specifically for transparent land leasing and mortgage management, emphasizing its capabilities in double-spending prevention, increasing transparency, and enhancing user participation.

2.3. Blockchain Applications in Housing Rental Systems

In recent years, a growing body of research has explored the application of blockchain technology to the housing rental sector. These studies aim to address persistent challenges in traditional rental markets, such as information asymmetry, lack of trust, inefficient contract execution, and fraud. Leveraging its inherent decentralization, immutability, transparency, and security properties, blockchain has emerged as a promising tool for revolutionizing rental management systems, demonstrating significant potential for enhancing both efficiency and trust.

Several key studies highlight different approaches. Qi-Long, C. et al. [12] proposed a blockchain-based system to establish a decentralized and tamper-proof rental information-sharing platform. Their research emphasized the transformation of traditional Rental Agreements into smart contracts to enable automated execution and on-chain data recording. The system architecture included distinct smart contracts for property listings, agreement generation, and lease management, with performance evaluations conducted on the Rinkeby test network to assess gas consumption and transaction costs.

Qi-Long, C. et al. [12] designed a consortium blockchain-based rental system jointly managed by landlords, leasing companies, and public housing authorities. This architecture segregated responsibilities across different ledgers for transaction records, identity certifications, and lease terms, thereby enabling collaborative governance and data partitioning.

In prior research, Hsieh et al. [10] proposed a hybrid architecture integrating Ethereum and Hyperledger Fabric. A Decentralized Identity Chain (DID-Chain) was designed for managing user identities, while a separate Rental House Chain handled core rental functions. The system aimed to create a secure, transparent, and privacy-preserving platform by involving multiple stakeholders, such as real estate agents and land management authorities. Its core processes included property verification, agent certification, lease management, and rent payment, with experimental evaluations focused on the throughput and response time of various smart contract functions.

Sharma et al. [4] explored the integration of Soulbound Tokens (SBTs) into a real estate rental platform. They argued that SBTs, as non-transferable digital assets, can effectively serve as a mechanism for tracking and verifying identities and property-related information, thereby enhancing trust and security. Their study highlighted the potential of SBTs in establishing robust digital reputation and trust frameworks.

Finally, Santos, J.F. et al. [11] proposed a decentralized and scalable approach utilizing a blockchain, peer-to-peer network, and InterPlanetary File System (IPFS) combination. Their Blockchain-Based Documentation Management (BDM) system stores large documents on off-chain storage solutions (e.g., IPFS, Google Cloud Storage) while recording the document hashes on the blockchain. This design ensures both content integrity and user privacy while providing immutable and traceable records for auditing and management purposes.

2.4. Core Technologies and Concepts

Blockchain-based housing rental systems integrate several key technologies to address the challenges of traditional rental markets and enhance system security, transparency, and efficiency.

2.4.1. Smart Contracts

Smart contracts are self-executing programs stored on a blockchain that automatically enforce the terms of an agreement [6]. They are event-driven stateful applications that run on a replicated and shared ledger and can manage on-chain assets.

Application in Rental Housing: Smart contracts are pivotal in automating the rental lifecycle. They can replace traditional paper-based agreements to manage rent and deposit payments, streamline the contract execution process, and handle breach-of-contract scenarios automatically [6]. By encoding predefined trigger conditions and response rules, smart contracts enhance the efficiency of rental processes and the fairness of transactions. Their public, transparent, and immutable nature makes them ideal for managing tasks such as automated rent collection and distribution or even initiating eviction protocols in cases of non-payment [4].

2.4.2. Decentralized Identity (DID) and Self-Sovereign Identity (SSI)

Self-Sovereign Identity (SSI) is a model where individuals own, control, and manage their digital identities without reliance on centralized authorities. Users maintain local control over their personal data, granting access to service providers only with explicit consent [3]. DID serves as the technical backbone for implementing SSI.

Application in Rental Housing: DID and SSI are instrumental in verifying the identities of landlords and tenants, thereby establishing a trusted transactional environment while preserving user privacy. For instance, a government authority can issue DIDs, ensuring a verifiable link between digital identities and real-world entities without centrally storing correlations [10]. This framework mitigates the risk of malicious or unverified actors participating in the platform [6].

2.4.3. Non-Fungible Tokens (NFTs)

NFTs are unique, non-interchangeable digital assets recorded on a blockchain, each representing a one-of-a-kind item [4].

Application in Rental Housing: In principle, NFTs could be used to represent unique property titles or rental rights, enabling the digital tokenization and management of real-world assets. However, the reviewed literature does not yet detail specific implementations of NFTs for this purpose in housing rental solutions.

2.4.4. Soulbound Tokens (SBTs)

SBTs are non-transferable, publicly verifiable tokens that function as permanent records of an individual’s credentials, affiliations, or commitments. Unlike NFTs, they cannot be bought or sold, rendering them ideal for representing reputation [4].

Application in Rental Housing: SBTs can be used to implement a decentralized reputation system. For example, an “Entry Token” SBT could be issued to new users to accumulate their transactional history and ratings on the platform. Mutual ratings between landlords and tenants, which are only possible upon the establishment of a formal rental relationship, can be recorded on their respective SBTs. This mechanism increases the credibility of the rating system and establishes a robust, reputation-based trust framework [4].

2.4.5. InterPlanetary File System (IPFS)

IPFS is a peer-to-peer protocol for storing and sharing data in a distributed file system, using content-addressing to uniquely identify each file.

Application in Rental Housing: Given the high cost of on-chain data storage, IPFS is well-suited for storing large files, such as property images and Rental Agreement documents. The file’s unique hash value is stored on the blockchain, while the file itself resides on IPFS. This hybrid approach ensures data integrity and availability while remaining cost-effective and efficient [4].

2.4.6. Hyperledger Fabric

Hyperledger Fabric is an open-source, permissioned blockchain platform hosted by the Linux Foundation. It features a modular architecture, pluggable consensus algorithms, and private communication channels that ensure data confidentiality among specific participants. Access control is managed through a Certificate Authority (CA) and X. 509 certificates, restricting network participation to trusted, verified members [11].

Application in Rental Housing: As a permissioned platform, Hyperledger Fabric is ideal for building enterprise-grade consortium blockchains for the housing rental industry [6]. Its architecture facilitates a network comprising diverse stakeholders (e.g., certification bodies, rental companies, and government authorities) [13], with transaction data segregated through channels to maintain privacy and enforce governance rules [4].

The synergistic application of these technologies aims to create a more equitable, transparent, and efficient housing rental market.

2.5. Research Gaps and Contribution of This Study

Our review of the existing literature indicates that while blockchain technology offers promising solutions for the housing rental market, several research gaps remain. Current studies have effectively explored applications in information sharing, contract automation, and identity verification. However, persistent challenges exist in key areas, including interoperability between disparate blockchain platforms, advanced user privacy preservation, and the scalability required for real-world adoption. Furthermore, the integration of these technological solutions within existing legal and regulatory frameworks remains a significantly underexplored area.

This research aims to address these gaps by designing and implementing a hybrid blockchain architecture tailored to the specific needs of the rental market in Taiwan. By combining a permissioned chain for rental operations with a public-facing DID chain for identity management, our system seeks to enhance user experience, privacy, and scalability. This study contributes to the field by proposing a practical, multi-chain solution that improves the efficiency, transparency, and security of the housing rental ecosystem while aligning with the operational realities of a government-regulated market.

3. System Design and Architecture

Building upon the analysis of challenges in the traditional rental market, this section details the design principles and overall architecture of the proposed blockchain-based housing rental system. Our objective is to establish a decentralized, secure, and transparent rental platform that effectively mitigates issues such as information asymmetry, fraudulent listings, and counterparty risk, thereby safeguarding the rights and interests of all participants.

3.1. Overall System Architecture

Figure 1, showing the proposed system, employs a multi-layered, hybrid blockchain architecture designed to leverage the distinct advantages of different blockchain platforms. At the same time, it is necessary to integrate trusted third-party verifiers to ensure data accuracy and reliability. The core components of this architecture are as follows:

• Permissioned Blockchain Layer (Rental House Chain):

This layer serves as the core data and transaction ledger for all rental activities. We adopt a consortium blockchain model, which is collaboratively maintained and governed by a pre-selected set of authorized nodes. Compared to public blockchains, consortium chains offer superior performance in transaction throughput, enhanced data privacy, and more efficient governance [3], making them highly suitable for regulated environments such as the housing rental market [13]. For this system, we utilize Hyperledger Fabric to implement this layer, named the Rental House Chain. Consortium members are envisioned to include trusted entities, such as land administration offices, financial institutions, real estate agencies, courts, and tax authorities.

• Decentralized Identity Blockchain Layer:

To ensure secure and privacy-preserving identity management, we introduce a dedicated Decentralized Identity (DID) system built on an independent blockchain. This layer, which can be implemented on a platform such as Ethereum or Hyperledger Fabric, allows users to autonomously manage their digital identities. Trusted institutions, such as government agencies, are responsible for issuing and verifying Verifiable Credentials (VCs), which are cryptographically linked to a user’s DID. This mechanism enables robust identity verification for both landlords and tenants while preserving user privacy.

• API and User Interface Layer:

This layer provides the user-facing interfaces through which tenants, landlords, and third-party verifiers interact with the underlying blockchain infrastructure. It comprises user-friendly decentralized applications (DApps) and a set of well-defined Application Programming Interfaces (APIs) [11]. Through this layer, users can perform essential operations, such as property listing, contract signing, and payment execution, with business logic automated via smart contracts.

• Trusted Third-Party Verification Authorities:

To prevent fraudulent property listings at their source, the architecture integrates trusted third-party organizations. These entities are responsible for the off-chain verification of information submitted by users. For instance, the Department of Land Administration (DLA) is tasked with verifying property ownership and real estate agency licenses. The verified outcomes are then recorded on the permissioned blockchain as immutable and verifiable claims [3], anchoring real-world trust to the digital system.

3.1.1. Decentralized Identity (DID) Chain

The proposed system architecture integrates a Decentralized Identity (DID) Chain to manage user identities. This infrastructure is developed on the Hyperledger Fabric platform and adapts the architecture proposed in our prior work [10].

In this framework, a designated government authority functions as the identity issuer. All users—including landlords, real estate agents, and tenants—must register using their official national identification numbers. Upon successful off-chain verification, the government computes a cryptographic hash of the user’s ID number and records this hash value on the DID-Chain. This process establishes a Decentralized Identity for the user while ensuring that the personally identifiable information (PII) itself remains off-chain in the government’s secure database, a design that is compliant with data privacy regulations such as GDPR [10].

The government then issues each verified user a unique Personal Identity (PI) smart contract, which is deployed on the DID-Chain. Ownership of this PI contract is transferred to the user, who manages it via their digital wallet. The PI contract serves as the on-chain representation of the user’s DID and as an interface for interacting with other blockchain applications, such as the Rental House Chain.

To register on the Rental House Chain (also built on Hyperledger Fabric), a user generates a Certificate Signing Request (CSR) and a corresponding cryptographic key pair for that network. The user’s private Rental House Chain key is stored locally and is never transmitted over the network. The CSR, containing the public key, is then submitted to their PI contract.

For transactions on the Rental House Chain, the user utilizes their locally stored private Fabric key to sign the transaction. The signature is created offline, ensuring that the private key remains exclusively under the user’s control. This design embodies the principles of Self-Sovereign Identity (SSI), granting users full autonomy over their digital identity and associated credentials [10].

3.1.2. Rental House Blockchain

The Rental House Chain is the primary permissioned blockchain in our system, which is responsible for managing all core rental-related transactions. It is built on Hyperledger Fabric and operates in conjunction with the DID-Chain to ensure that all participants are authenticated.

The interaction between the two chains is managed through the user’s Personal Identity (PI) smart contract, which resides on the DID-Chain. To participate in the Rental House Chain, a user must first be registered on the DID-Chain, as detailed in Section 3.1.1.

The registration process for the Rental House Chain involves the following steps:

• A user generates a new cryptographic key pair specifically for interacting with the Hyperledger Fabric-based Rental House Chain.
• The private key for this chain is stored securely on the user’s local client (e.g., within their wallet) and is never exposed to the network.
• The user creates a Certificate Signing Request (CSR), which includes the public key of the newly generated key pair.
• This CSR is then submitted to the user’s PI contract on the DID-Chain. This action links their verified Decentralized Identity to their new account on the Rental House Chain.

For all subsequent transactions on the Rental House Chain (e.g., listing a property or signing a lease), the user employs their locally stored private Fabric key to sign the transaction. This offline signing mechanism ensures that private keys remain exclusively under user control, adhering to the principles of Self-Sovereign Identity (SSI) and providing robust security for all on-chain activities.

Figure 2 illustrates the comprehensive architecture of the Rental House Chain, a blockchain-based platform designed to enhance trust and transparency in the housing rental market. The blockchain infrastructure is structured around three primary channels—register-channel, lease-channel, and acc-channel—and incorporates five core smart contracts: Estate Register, Estate Agent, Estate Publish, Rental Agreement, and Access Control Manager. Each smart contract executes a distinct function within the ecosystem, with its functionalities detailed in the subsequent section.

In Figure 2, the network is governed by a consortium of four primary organizations: the Department of Land Administration (DLA), the System Application provider, the court, and the National Taxation Bureau (NTB). The system serves three main user roles: landowners, estate agents, and tenants. The functions of each component are detailed below.

• Blockchain Channels

Lease Channel: This channel manages all data related to public rental activities, including agency entrustment records, property listings, and finalized Rental Agreements. It is co-managed by all consortium members (DLA, System Application, the court, and NTB) and provides public read access to promote market transparency.

Access Control Channel (acc-channel): Administered exclusively by the NTB, this private channel is dedicated to managing access permissions for sensitive tenant data. Through this channel, tenants can grant the NTB consent to verify their financial information (e.g., income) and provide attestations to landlords without exposing the underlying data.

Register Channel: This channel is responsible for recording and managing all identity and certification data, including property ownership records and real estate agent licenses.

2.

Consortium Organizations

Department of Land Administration (DLA): As a governmental authority, the DLA serves as the official certifier for land ownership and real estate agent licenses. It is responsible for validating these credentials off-chain and recording the verification results on the blockchain, thereby establishing a foundational layer of trust.

System Application: This component refers to the decentralized application (DApp) that serves as the primary user interface to the blockchain. It retrieves and presents on-chain data to users and facilitates user interactions, such as submitting transactions for signing and execution.

Court: The court fulfills a regulatory and validation role, ensuring the legal integrity of Rental Agreements. It stores a hash or official record of notarized contracts, guaranteeing their legal enforceability.

National Taxation Bureau (NTB): The NTB plays a dual role in verification and compliance. With explicit user consent, it acts as a trusted third-party verifier for financial data. Additionally, it can monitor on-chain rental transactions to ensure tax compliance.

3.

System Users

Landowner: The landowner is the verified owner of a real estate property, initiating the rental process by listing their property after their ownership has been certified by the DLA.

Estate Agent: An estate agent is a government-licensed professional who acts as an intermediary for the landowner. The agent is authorized to manage property listings, negotiate terms, and facilitate Rental Agreements.

Tenant: A tenant is an individual or entity seeking to lease a property. Tenants use the system to search for available listings and enter into legally binding rental contracts with landowners.

3.2. Smart Contract Design

The smart contracts for the DID-Chain are consistent with those detailed in our prior study [10] (Section 3.2.1). Therefore, this section focuses exclusively on the smart contract designs implemented within the Rental House Chain.

3.2.1. Estate Register Contract

The Estate Register contract (Figure 3) operates within the Register Channel and is jointly managed by the Department of Land Administration (DLA) and the System Application. As a foundational component of the system, this smart contract is responsible for recording verified real estate ownership information and creating an immutable link between a property and its owner’s digital identity.

Data within this contract is structured as a key-value store, where the index key is a composite of the property owner’s public key and the property address. The corresponding value is a data structure named estateInfo, which encapsulates the detailed property attributes specified in

Table 1. DLA-verified estate information.

Variable	Type	Description
address	string	The address of the estate.
area	number	The area of the estate.
date	string	The issue date of the land ownership certificate.

. Each verified property corresponds to a unique estateInfo instance on the blockchain.

The operational flow is as follows.

After the DLA completes its off-chain verification of a property ownership certificate, it invokes the UploadPersonalEstate function. This action records the corresponding estateInfo structure on the blockchain and associates it with the property owner’s account.

Subsequently, the System Application can retrieve this verified information by calling the GetEstate function, using the owner’s public key and property address as query parameters. This enables downstream processes to programmatically verify a property’s authenticity before it is listed for rent.

This contract design ensures that all property data within the system are authoritatively verified and reliably sourced. By mandating validation from the official land administration authority, this mechanism effectively mitigates the risk of fraudulent listings at the foundational level.

3.2.2. Estate Agent Contract

The Estate Agent contract (Figure 4) operates on the Lease Channel and is co-managed by the Department of Land Administration (DLA) and the System Application. Its primary responsibilities are twofold: first, to maintain an on-chain registry of certified real estate agents, and second, to manage the property entrustment process between landowners and agents.

Agent Certification Management:

Agent certification data, provided by the DLA, are stored in a data structure named Certificate, as defined in

Table 2. Table of the Certificate structure.

Variable	Type	Description
address	string	The public key of the estate agent.
expDate	string	The certificate’s expiration date.

. Each record is indexed by the agent’s public key, with the corresponding value containing certificate metadata and the agent’s address. The DLA uses the NewAgent function to record a new agent’s certification on the blockchain. Subsequently, the System Application can query this information via the GetAgentCertificate function to programmatically verify an agent’s credentials.

Property Entrustment Management:

Landowners can delegate the management of their properties to certified agents. These entrustment records are stored using a composite key derived from the agent’s public key and the property address. The associated data structure includes owner information, property details, and the delegation status. The workflow is as follows:

• A landowner initiates an entrustment request by invoking the AddEstate function, targeting a specific agent.
• The designated agent can then respond by calling either the AcceptEstate or RejectEstate function to approve or decline the request.
• The System Application can retrieve details of a specific delegation using the GetAgentEstate function or access all entrustment records for a particular agent via the GetAllAgentEstate function.

This dual-function contract design establishes a trusted framework for agent verification and property delegation, ensuring that all agent-led activities are authorized and traceable.

Table 3. Table of the Agreement structure.

Variable	Type	Description
ownerAddress	string	The address of the estate owner.
estateAddress	string	The address of the estate.
type	string	Records the type of entrustment, whether it is only responsible for renting or includes management after renting out.
state	string	Records whether the real estate agent has accepted the entrustment.

details the Agreement data structure, which records the authorization for a real estate agent to manage a specific property on behalf of a landowner. This structure is indexed by a composite key, derived from the agent’s public key and the property address, ensuring a unique record for each entrustment. It stores critical data, including the landowner’s identity, the property address, the type of entrustment, and its current status (e.g., pending, active, or rejected).

The lifecycle of an entrustment is managed through the following functions:

• AddEstate: Invoked by a landowner to submit an entrustment request to a designated real estate agent.
• AcceptEstate/RejectEstate: Invoked by the designated agent to approve or decline the pending entrustment request.
• The system also provides two query functions for retrieving these records:
• GetAgentEstate: Retrieves the details of a single, specific entrustment record.
• GetAllAgentEstate: Retrieves all entrustment records associated with a particular real estate agent.

This contract design provides a transparent, accountable, and traceable framework for delegating property management responsibilities, thereby enhancing trust between landowners and licensed estate agents.

3.2.3. Estate Publish Contract

The Estate Publish contract (Figure 5) operates on the Lease Channel and is governed by the consortium of participating organizations. This smart contract is designed to manage the lifecycle of rental property listings. The core data is stored in the estateInfo structure (detailed in

Table 4. Table of the estateInfo structure.

Variable	Type	Description
uploader	string	The public key of the estate uploader. The uploader may be a landowner or a real estate agent.
estateAddress	string	The address of the estate.
owner	string	The address of the estate owner.
rent	int	Rent is registered for this property by the landlord.
state	string	Records the rental situation.
restriction	json	The conditions that the landlord hopes for from the tenant; the restricted item is used as the key, and the corresponding value is used as the value.

), which is indexed by a composite key derived from the landlord’s public key and the property address. This structure encapsulates the rental terms and property-specific details provided by the landlord.

The contract exposes several functions for managing and querying these listings:

Listing Creation and Status Management:

• NewListing: Invoked by a landlord to publish a new rental listing, which sets its initial status to “Online”.
• ListingSigned: Called by the Rental Agreement contract upon the successful execution of a lease. This function updates the listing’s status, effectively removing it from the pool of available properties.

Query Functions:

• GetAllOnlineListing: Retrieves all listings currently marked as “Online,” serving as the primary function for property discovery.
• GetListing: Retrieves detailed information for a single, specific listing.
• GetListingCondition: Retrieves any eligibility conditions or constraints associated with a specific listing.
• GetPersonListing: Retrieves all listings published by a specific landlord, identified by their public key.

This design ensures the integrity and real-time accuracy of available rental listings on the platform. By automatically updating a listing’s status upon contract execution, the system prevents properties that are no longer available from appearing in search results.

3.2.4. Rental Agreement Contract

The Rental Agreement contract (Figure 6) operates on the Lease Channel and is co-managed by the court and the National Taxation Bureau (NTB). This smart contract is responsible for recording the metadata of finalized Rental Agreements and the digital signatures of all contracting parties. It serves as the immutable, on-chain proof of the contractual relationship.

To ensure data confidentiality and cost-efficiency, the full rental contract text is stored off-chain within the court’s secure database. The court generates a cryptographic hash of the contract, agreementHashed, which serves as a unique digital fingerprint. This hash is then recorded on the blockchain. The agreementInfo data structure (see

Table 5. Table of agreement Info structure.

Variable	Type	Description
address	string	The address of the lease item.
partyA	string	The public key of the landlord.
partyB	string	The public key of the tenant.
agreementHashed	string	The hashed value of this agreement in the database.

) is indexed by a composite key derived from the landlord’s public key and the agreementHashed value. This structure stores essential on-chain metadata, including a unique contract identifier, the public keys of the landlord and tenant, and their respective digital signatures (see

Table 6. Table of sign structure.

Variable	Type	Description
partyA	string	The signature of the landlord. It can be verified by agreementHashed and the landlord’s public key.
partyB	string	The signature of the tenant. It can be verified by agreementHashed and the tenant’s public key.

). All signatures are generated using Elliptic Curve Cryptography (ECC), ensuring cryptographic authenticity.

The contract execution workflow proceeds as follows:

• The landlord submits the finalized agreement to the court’s off-chain system.
• The court invokes the CreateAgreement function, which records the agreementHashed and associated metadata on the blockchain.
• Both the landlord and the tenant then individually invoke the SignAgreement function to submit their digital signatures to the contract.
• Once both signatures are recorded, the VerifyAgreementSign function can be called to validate their authenticity.

Upon the successful verification of all signatures, the agreement is considered fully executed and legally binding on the blockchain. This design establishes a secure, tamper-proof, and verifiable Rental Agreement process, supporting legal enforceability and accountability through court-managed oversight and on-chain signature verification.

3.2.5. Access Control Manager Contract

The Access Control Manager (Figure 7) contract operates on the private acc-channel and is co-managed by the National Taxation Bureau (NTB) and the Department of Land Administration (DLA). This smart contract implements a granular, consent-based access control mechanism, enabling tenants to authorize trusted third parties (e.g., the NTB) to verify their qualifications without directly exposing sensitive personal data.

The core of this contract is the Permission data structure. Each user is identified by their public key, which indexes their Permission structure (

Table 7. Table of Permission structure.

Variable	Type	Description
type	string	The key to this type of access control data.
access	string	The access set by the user.
endTime	string	The expiry date of the type of access right.

). This structure contains multiple categories of personal data attestations (e.g., income level verification, background check status) and maps each category to a specific set of access permissions.

Users retain full autonomous control over their data permissions through two primary functions:

• UpdatePermission: Allows a user to grant or modify access rights for a specific data category to a designated verifier.
• RevokePermission: Allows a user to permanently revoke a previously granted access right.

When a landlord requests qualification verification, the NTB first invokes the GetPermission function to retrieve the tenant’s current explicit consent settings. This ensures that only authorized data categories are accessed for verification. Furthermore, every access request and verification event is immutably logged on the blockchain, including the requesting landlord’s public key. This provides a fully transparent and auditable trail of all permissioned data access.

This contract design directly supports contemporary data privacy principles, such as data minimization and purpose limitation. By facilitating the third-party verification of attestations rather than direct data disclosure, the system ensures user-centric control, enhances transparency, and aligns with data protection regulations such as GDPR [14].

3.3. Mapping of User Roles to Smart Contract Functions

Table 8. This table presents the function list of the Estate Register contract chaincode.

Function	Permitted Roles	Description
UploadPersonalEstate()	Department of Land Administration (DLA)	Used by the Land Administration Authority (DLA) to upload verified real estate ownership information to the blockchain and securely link it to the owner’s account, addressing the issue of fraudulent property listings at the source.
GetEstate()	System Application	To enable the System Application to query real estate ownership information and verify the authenticity of a property using the owner’s public key and the property’s address in order to support subsequent rental processes.

,

Table 9. This table presents the function list of the Estate Agent contract chaincode.

Function	Permitted Roles	Description
NewAgent()	Department of Land Administration (DLA)	The Land Administration Authority (DLA) uploads real estate agent certification data to the blockchain, linking the agent’s public key with their verified credentials to ensure that only authorized agents can participate in transactions.
GetEstate()	System Application	Used by the System Application to query agent certification data in order to verify the agent’s identity and credentials.
AddEstate()	Property Owner	The property owner initiates a delegation request to a designated certified real estate agent, including the property to be delegated and the type of delegation (rental-only or full delegation).
AcceptEstate()	Real Estate Agent	The real estate agent accepts the delegation request from the property owner and is officially granted management authorization.
RejectEstate()	Real Estate Agent	The real estate agent rejects the delegation request from the property owner.
GetAgentEstate()	Property Owner/ Real Estate Agent (via System Application)	Query detailed information of a specific delegation record based on the agent’s public key and the property address for use by relevant parties.
GetAllAgentEstate()	Property Owner/ Real Estate Agent (via System Application)	Query all delegation records associated with a specific real estate agent.

,

Table 10. This table presents the function list of the Estate Publish contract chaincode.

Function	Permitted Roles	Description
NewListing()	Landlord/ Authorized Agent	Allows the landlord or their authorized agent to publish a new rental listing on the blockchain and set its status to “online”.
GetAllOnlineListing()	Tenant/ System Application()	Provides tenants with a list of all available rental properties currently marked as “online,” serving as a key read operation in the system.
GetListing()	User/Tenant (via System Application)	Allows users to obtain detailed information and lease terms of a specific property using the landlord’s public key and property address.
GetListingCondition	User/Tenant (via System Application)	Queries the restrictions and tenant eligibility requirements for a specific property.
GetPersonListing()	Landlord/ System Application	Retrieves all property listings associated with a given landlord’s public key.
ListingSigned()	Rental Agreement Contract/court	After the lease agreement is signed, the status of the property is updated to remove it from “online” listings, ensuring the timeliness and accuracy of property information on the platform.

,

Table 11. This table presents the function list of the Rental Agreement contract chaincode.

Function	Permitted Roles	Description
CreateAgreement()	Court	The court records the encrypted hash value and related metadata of the Rental Agreement on the blockchain, serving as an immutable digital fingerprint of the agreement.
SignAgreement()	Landlord/Tenant	The landlord and tenant upload their digital signatures of the agreement’s hash value to the smart contract, confirming mutual agreement on the terms and ensuring the legality and authenticity of the contract.
VerifyAgreementSign()	Court/System Application	Verify the authenticity of the landlord’s and tenant’s digital signatures to ensure that they match the original agreement hash value. Upon successful verification, this function triggers the Estate Publish contract to update the property status to “Signed,” marking the agreement as officially effective and recorded on the blockchain.

and

Table 12. This table presents the function list of the Access Control Manager contract chaincode.

Function	Permitted Roles	Description
UpdatePermission()	Tenant	Tenants update or assign access permissions to their specific personal data (such as income records or background check results), allowing them full control over data usage and enabling user-centric data governance.
GetPermission()	National Tax Bureau (NTB)	Allows third-party organizations (such as the National Tax Bureau, NTB) to retrieve the tenant’s latest permission settings, enabling verification of the tenant’s eligibility (e.g., income) without directly exposing sensitive data, thereby protecting the tenant’s privacy.

present a matrix that maps the system’s smart contract functions to their corresponding user roles. This mapping provides a clear and systematic overview of the permissions and capabilities associated with each role—landowner, estate agent, and tenant—as well as the administrative functions assigned to consortium organizations such as the DLA and the court.

This structured representation not only elucidates the specific responsibilities of each smart contract but also demonstrates how these functions collaboratively address the challenges of the traditional rental market. By defining and enforcing these roles at the contract level, the system enhances transparency, security, and operational efficiency across the entire rental ecosystem.

3.4. Security Analysis

The proposed blockchain-based housing rental system is engineered with a multi-layered security posture, integrating the inherent characteristics of blockchain technology, Decentralized Identity (DID), and other cryptographic safeguards. This robust design is intended to mitigate various cyber threats, ensuring data integrity, user privacy, and system availability.

3.4.1. Resilience Against Distributed Denial-of-Service (DDoS) Attacks

The system’s foundation in Hyperledger Fabric, a permissioned distributed ledger [15], provides inherent resilience against DDoS attacks. Unlike centralized systems that rely on a single server, our architecture distributes data and transaction processing across a network of authorized nodes. In this decentralized environment, first conceptualized in peer-to-peer systems [8], there is no single point of failure. The disruption of a limited number of nodes will not compromise overall system availability, as the remaining operational nodes can continue to process and validate transactions, ensuring continuous service.

3.4.2. Mitigation of Man-in-the-Middle (MitM) Attacks

The system employs several mechanisms to counter MitM attacks:

• Cryptographic Integrity and Immutability: All transactions are secured using advanced cryptographic primitives, such as hash functions and digital signatures. The integrity of the ledger is maintained through a consensus mechanism that validates every block. This cryptographic linkage ensures that any unauthorized data tampering would be immediately detectable, as it would invalidate the hash of the tampered block and all subsequent blocks [3,6]. Once recorded, a transaction becomes a permanent and immutable part of the ledger, making retroactive alteration computationally infeasible.
• Offline Signing Mechanism: A cornerstone of our security design is the offline signing mechanism, which adheres to the principles of Self-Sovereign Identity (SSI) [10,16]. All transaction proposals are signed on the user’s local, secure client-side environment (e.g., their wallet). This critical design ensures that a user’s private keys are never exposed to the network or any server. Only the signed transaction, which is publicly verifiable but impossible to forge without the private key, is transmitted. This approach completely eliminates the risk of private keys being intercepted by a MitM attacker during network transmission, thereby guaranteeing transaction authenticity and non-repudiation.
• Immutable Agreement Fingerprints: To prevent tampering with Rental Agreements, the system records the cryptographic hash of each contract on the blockchain, creating a secure, immutable “digital fingerprint” [11]. Following this, the digital signatures of all contracting parties are also recorded on-chain. Any attempt by a MitM attacker to surreptitiously alter the agreement’s content after it has been signed would result in a hash mismatch, rendering the tampering attempt immediately obvious and futile. This method of ensuring data integrity by storing hashes on-chain is a common practice in blockchain applications, including those outside of real estate applications [9].

3.4.3. Mitigation of Spoofing and Impersonation Attacks

The system implements multi-layered identity and asset verification mechanisms to preempt spoofing and impersonation attacks:

• Decentralized Identity (DID) System: Our DID solution, adapted from prior research [10], is central to user authentication. All participants must register using their official national identification numbers, which are verified off-chain by a government authority. The authority then records a cryptographic hash of the ID on the DID-Chain, creating a tamper-proof link between a real-world identity and a digital one. Since only the government authority can issue these Verifiable Credentials, this design effectively prevents malicious actors from creating fraudulent identities or impersonating legitimate users on the platform [6].
• Permissioned Blockchain Access Control: The use of Hyperledger Fabric provides an intrinsic layer of network security [15]. Its permission mechanism requires all participating nodes and users to be authenticated via a Certificate Authority (CA) and issued X. 509 certificates. This ensures that only pre-vetted trusted entities can join and transact on the network, fundamentally preventing unauthorized actors from gaining access to the core infrastructure.
• Dual Verification of Property and Identity: To prevent asset spoofing, all rental properties must undergo a dual-verification process. First, the Department of Land Administration (DLA) certifies property ownership. Second, the property owner’s identity is verified via the DID-Chain. Only after both verifications are successfully recorded on-chain is a property eligible for listing. This robust mechanism effectively eliminates the risk of fraudulent property listings and establishes a foundational layer of asset authenticity.

3.4.4. Resilience Against 51% Attacks

The system’s adoption of a consortium blockchain architecture fundamentally mitigates the risk of a 51% attack. Unlike public proof-of-work blockchains, where such an attack can be mounted by amassing sufficient computational power [8], a consortium chain is governed by a pre-selected group of trusted and identifiable organizations [6,13].

In our proposed model, these consortium members would include reputable entities, such as the DLA, courts, and financial institutions. To alter the ledger, an attacker would need to compromise the security of and gain control over a majority of these distinct, trusted organizations—a feat that is orders of magnitude more difficult and less feasible than acquiring hashing power on an anonymous public network. This architectural choice significantly elevates the threshold for a successful attack, thereby augmenting the overall security and integrity of the ledger.

4. Workflow

4.1. Workflow Overview

The system’s workflow begins with a one-time user registration on the DID-Chain, which establishes a secure and verifiable digital identity for each participant. Following this identity registration, users can authenticate themselves with respect to the Rental House Chain system using their blockchain address and associated private key. This authentication process is consistent with the methodology detailed in our prior study [10] (Section 4.1).

Once authenticated, users can engage in the core rental process, which is structured into seven sequential steps:

• Property Registration: A landowner verifies and registers their property on the blockchain.
• Estate Agent Registration: A real estate agent verifies and registers their professional credentials.
• Property Entrustment: A landowner delegates management authority for a property to a registered agent.
• Rental Listing Publication: The landowner or their designated agent publishes a rental listing for the property.
• Property Search and Tenant Application: A prospective tenant searches for properties and submits a rental application.
• Rental Agreement Creation: The landowner drafts and proposes a formal Rental Agreement.
• Rental Agreement Execution: Both parties digitally sign the agreement, rendering it legally binding on the blockchain.

Each of these steps will be detailed in the subsequent sections, outlining how the system leverages blockchain technology to ensure transparency, data integrity, and trust throughout the entire rental lifecycle.

4.2. Property Registration and Verification

Before a property can be listed for rent, a landowner must complete a two-stage process: first, obtaining an official ownership certification from the Department of Land Administration (DLA), and second, registering the certified property within the Rental House Chain system.

4.2.1. Off-Chain Ownership Verification by the DLA

The initial and most critical step is the verification of property ownership by the DLA. This workflow, as illustrated in Figure 8, proceeds as follows:

• The landowner submits their national identification number and property address to the DLA’s off-chain system.
• The DLA queries its internal governmental registry to validate the authenticity of the ownership claim.
• Simultaneously, the DLA verifies the landowner’s identity. This is achieved by hashing the submitted ID number and comparing it against the corresponding hash stored on the DID-Chain. A match confirms that the identity claim is legitimate.

Upon the successful validation of both property ownership and user identity, the DLA invokes the UploadPersonalEstate function in the Estate Register smart contract. This on-chain transaction records the verified ownership data, including the owner’s public key and a reference to the land ownership certificate, thereby creating an immutable and authoritative record.

4.2.2. On-Chain Property Registration Within the System

Following successful DLA certification, the landowner can formally register the property within the Rental House Chain application. This process is depicted in Figure 9.

The landowner initiates a registration request through the System Application. The application then uses the landowner’s public key to query the Estate Register contract on the blockchain and retrieve the DLA-certified ownership data. Once retrieved, this data is cached in the application’s local database to optimize performance for subsequent operations. A confirmation message is then returned to the user, completing the registration process.

This dual-layered approach ensures that all properties listed on the platform are anchored to an official, DLA-verified ownership record, fundamentally preventing fraudulent listings and enhancing the trustworthiness of the entire rental ecosystem.

4.3. Real Estate Agent Registration and Verification

To operate as a real estate agent within the system, a user must complete a two-stage registration and verification process, which mirrors the property registration workflow. This ensures that only government-licensed professionals can offer intermediary services.

4.3.1. Off-Chain License Verification by the DLA

The initial step requires the prospective agent to submit their professional certification and national identification number to the Department of Land Administration (DLA). This process is illustrated in Figure 10. The DLA performs two parallel verification actions:

It queries its internal registry of licensed professionals to confirm the validity of the submitted certification.

It verifies the user’s identity by hashing their submitted ID number and matching it against the corresponding hash on the DID-Chain.

Upon successful validation of both the professional license and the user’s identity, the DLA invokes the NewAgent function in the Estate Agent smart contract. This on-chain transaction creates an immutable record that cryptographically links the agent’s public key to their verified professional credentials.

4.3.2. On-Chain Credential Confirmation Within the System

Once the DLA has recorded the certification on-chain, the agent can be formally recognized within the Rental House Chain application. As depicted in Figure 11, this involves the System Application querying the Estate Agent’s contract.

The application utilizes the GetAgentCertificate function, using the agent’s public key as the query parameter, to retrieve the DLA-certified credential data from the blockchain. Successful retrieval and validation of this data confirms the user’s status as a licensed real estate agent. This completes the registration process, officially authorizing the user to perform intermediary functions such as managing property listings and representing landowners.

This structured, dual-layered process guarantees that only government-verified agents can participate in rental operations, thereby reinforcing system security, regulatory compliance, and overall user trust.

4.4. Property Entrustment to a Real Estate Agent

Following the successful verification of both the landowner’s property and the real estate agent’s credentials, the landowner may delegate rental management responsibilities to the agent. This entrustment workflow is depicted in Figure 12.

4.4.1. Initiating the Entrustment Request

To initiate the process, the landowner selects the certified property and the designated real estate agent. A critical step in this process is defining the type of entrustment, which determines the agent’s scope of authority:

Leasing-Only Entrustment: The agent is authorized solely to manage pre-lease activities, such as listing the property and finding a tenant. The final Rental Agreement must be signed by the landowner.

Full Entrustment (Sub-Landlord): The agent is granted comprehensive management responsibilities, including post-lease activities. In this capacity, the agent acts as a sub-landlord and is authorized to sign the Rental Agreement on behalf of the landowner.

The landowner then formalizes the request by invoking the AddEstate function in the Estate Agent smart contract. This transaction is executed via the Offline Sign mechanism, where the request is signed locally using the landowner’s private key before being submitted to the network. This ensures the security and authenticity of the authorization.

4.4.2. Agent Response and Finalization

Upon receiving the entrustment request, the designated real estate agent must respond by either accepting or rejecting it. This decision is also committed to the blockchain by invoking either the AcceptEstate or RejectEstate function, again using the Offline Sign procedure to ensure verifiable consent.

Once the agent’s response is recorded on-chain, the landowner receives a notification of the outcome. If the agent accepts, they are formally authorized within the system to manage the entrusted property and proceed with all subsequent rental activities as per the terms of the entrustment.

4.5. Offline Signing Transaction Flow

The offline signing process, as illustrated in Figure 13, is a critical security mechanism within the Rental House Chain system. It ensures that a user’s private key never leaves their secure, local environment (e.g., a client-side wallet), thereby decentralizing key management and safeguarding against network-based threats.

This process, which aligns with the standard transaction flow in Hyperledger Fabric, can be broken down into the following stages:

• Transaction Proposal: The user, via the client application, initiates a transaction by submitting the required parameters for a specific smart contract function. The client application uses these parameters to construct a transaction proposal.
• Simulation and Endorsement: The client application sends this proposal to one or more designated endorsing peers in the network. Each peer simulates the transaction, verifies the client’s signature, and generates a proposal response (also known as an endorsement), which it signs with its own private key and returns to the client.
• Transaction Assembly: The client application collects the signed proposal responses from the endorsing peers. It verifies the peers’ signatures and ensures that the responses are consistent and satisfy the smart contract’s endorsement policy. The client then assembles these endorsements into a final transaction payload.
• Submission to Ordering Service: The client application submits the complete transaction payload (containing the original proposal and all endorsements) to the ordering service.
• Ordering and Block Creation: The ordering service sequences all received transactions into a cryptographically linked block. It does not inspect the transaction content but simply establishes a definitive order.
• Validation and Ledger Commit: The ordering service broadcasts the newly created block to all committing peers in the network. Each peer independently validates every transaction within the block, checking for endorsement policy fulfillment and ensuring there are no state conflicts.
• Ledger Update: Upon successful validation, each committing peer appends the block to its local copy of the ledger, and the world state is updated accordingly. The client application is then notified of the transaction’s successful commitment.

This offline signing procedure is fundamental to the system’s security. By ensuring that the user’s private key is used only for local signing in the initial step, the entire workflow guarantees the authenticity and non-repudiation of transactions without ever exposing sensitive credentials to the network or any intermediary server.

4.6. Rental Listing Publication

The process for publishing a rental listing on the platform, as depicted in Figure 14, involves several secure and verifiable steps designed to ensure the authenticity of all rental offerings.

The workflow begins after the property has been successfully registered and verified. The landlord or their designated agent first prepares the listing’s descriptive content, which includes textual information, photographs, and other multimedia files. Given the storage constraints and costs associated with blockchain, this large-format data is stored in the system’s off-chain database.

Next, the landlord defines the on-chain rental parameters, such as the rental price and specific lease conditions (e.g., minimum duration, tenant eligibility criteria). Before this information can be committed to the blockchain, the system performs a critical authorization check. It verifies that the user initiating the transaction is one of the following:

• The verified property owner, as confirmed by the Estate Register contract.
• A certified real estate agent who has been officially entrusted with management rights for that specific property, as recorded in the Estate Agent contract.

Upon successful authorization, the landlord or agent uses the Offline Sign mechanism to sign the transaction proposal. This signed transaction then invokes the NewListing function within the Estate Publish smart contract, which creates a new, immutable rental listing record on the blockchain.

Once the transaction is successfully committed to the ledger, the rental listing is marked as “Online” and becomes discoverable by prospective tenants through the system’s search interface. This comprehensive process ensures that all listings are authentic, authorized, and traceable, thereby enhancing trust and transparency throughout the rental ecosystem.

4.7. Property Search and Tenant Application

This section details the workflow for prospective tenants, covering the search for available properties, the submission of rental applications, and the subsequent privacy-preserving qualification review.

4.7.1. Property Search and Expression of Interest

As illustrated in Figure 15, the process for a tenant to find and apply for a rental property is structured and secure.

• Property Discovery: When a landlord publishes a rental listing, its status is set to “Online.” Prospective tenants can then access a comprehensive list of all active listings via the System Application. The application calls the GetAllOnlineListing function to retrieve this data directly from the blockchain, ensuring that all displayed listings are current and verifiable on-chain.
• Detailed Review: If a tenant is interested in a particular listing, they can request its detailed information. By providing the landlord’s and the property’s addresses, the System Application retrieves the full listing details, including rental terms, conditions, and any specific eligibility requirements set by the landlord.
• Application Submission: After reviewing the details, the tenant can submit a formal expression of interest (i.e., a rental application) through the application. This action notifies the landlord of the tenant’s interest and initiates the subsequent stages of the rental process.

4.7.2. Privacy-Preserving Qualification Review

As depicted in Figure 16, the system incorporates a privacy-preserving verification mechanism that allows landlords to evaluate a tenant’s eligibility without direct access to sensitive personal data. This process is mediated by a trusted third party, such as the National Taxation Bureau (NTB).

The workflow proceeds as follows:

• Tenant Consent: To enable this feature, the tenant must first grant consent. Using the Offline Sign mechanism, the tenant signs a transaction that authorizes the NTB to perform specific data checks on their behalf. This creates a verifiable, on-chain proof of consent.
• Landlord Request: After receiving a rental application, the landlord can issue a qualification review request to the NTB. Before proceeding, the NTB verifies that the tenant has granted the necessary permissions and immutably logs with respect to the landlord’s request on the blockchain, creating a tamper-proof audit trail.
• Off-Chain Verification: The NTB then retrieves the eligibility criteria from the on-chain rental listing by using the GetListingRestriction function. It cross-references these criteria with the tenant’s confidential off-chain data (e.g., income records).
• Result Attestation: Based on this comparison, the NTB returns a simple, binary attestation to the landlord: “pass,” “fail,” or “permission denied.” Crucially, no raw personal data (e.g., actual income figures) is ever disclosed to the landlord.

This privacy-preserving review system allows for landlord due diligence while upholding tenant confidentiality, thereby fostering a more transparent and trustworthy rental ecosystem.

4.8. Rental Agreement Creation and Execution

The system implements a contract execution process inspired by judicial notarization, where the court acts as a trusted custodian for Rental Agreements. This workflow establishes a secure mechanism for contract storage and verification.

4.8.1. Rental Agreement Creation and On-Chain Registration

Once a landlord selects a tenant, the agreement creation phase begins, as depicted in Figure 17.

• Authorization Check: Before proceeding, the system performs a critical authorization check. If the party creating the contract is an entrusted real estate agent, the system verifies that their entrustment agreement grants them the authority to sign on behalf of the landowner.
• Off-Chain Storage: The landlord (or authorized agent) drafts the complete Rental Agreement and submits it to the court’s secure off-chain database. This ensures the confidentiality of the full contract text.
• On-Chain Fingerprinting: The court system then generates a cryptographic hash of the agreement (agreementHashed), which serves as its unique, immutable “digital fingerprint.” The court invokes the CreateAgreement function to record this hash and other essential metadata on the blockchain, placing the agreement into a “pending signature” state.

4.8.2. Digital Signature Execution and Contract Activation

Following the on-chain registration of the contract’s metadata, the final execution requires digital signatures from all contracting parties, as illustrated in Figure 18 and Figure 19.

The workflow proceeds as follows:

• Signature Generation (Offline): The landlord and tenant are prompted by the System Application to sign the agreementHashed value. Each party uses a locally stored private key to generate a unique digital signature. This cryptographic operation is performed entirely within the user’s secure client environment, ensuring that their private key is never exposed.
• Signature Submission: Each party then invokes the SignAgreement function to submit their respective digital signature to the Rental Agreement smart contract.
• Verification and Activation: Once all signatures are submitted, a final verification step is initiated. This action activates the VerifyAgreementSign function, which performs on-chain verifications to validate each signature against the agreementHashed using the corresponding public keys.
• Finalization and Status Update: Upon successful verification of all signatures, the VerifyAgreementSign function executes two critical actions:
  • It updates the Rental Agreement’s status to “Active,” marking it as fully executed and legally binding.
  • It triggers a cross-contract call to the Estate Publish contract to update the property listing’s status to “Signed,” thereby removing it from the public marketplace.

The court then communicates the final outcome to all parties. This comprehensive process guarantees the integrity, non-repudiation, and legal enforceability of the agreement, providing a transparent and tamper-proof record on the blockchain.

5. Experimental Evaluations

5.1. Analysis of the Proposed Solution

This section analyzes how the proposed Rental House Chain system addresses the four critical challenges identified in the Introduction: unverifiable property listings, lack of market transparency, inadequate lease protection, and vulnerabilities in personal data sharing.

• Unverified Property Listings

To mitigate the risk of fraudulent property listings, the system mandates that all rental properties must first be certified by the Department of Land Administration (DLA). This certification is recorded on-chain, ensuring that only legitimately owned properties are eligible for listing. Concurrently, property owners must authenticate their identities via the Decentralized Identifier (DID) Chain prior to registration. This dual-verification mechanism, which validates both property ownership and owner identity, effectively eliminates the circulation of unverified or fraudulent rental listings.

2.

Lack of Market Transparency

The system enhances market transparency by recording all critical rental-related processes—including property certification, agent entrustments, and contract execution—on the blockchain. The inherent immutability of the blockchain renders these records both tamper-proof and publicly verifiable. Although the current implementation does not feature a unified data aggregation interface, all on-chain information remains fully queryable and accessible. This framework offers substantial improvements in visibility and accountability across the rental ecosystem.

3.

Inadequate Lease Protection

To strengthen legal protection for Rental Agreements, the system integrates with the court system by storing finalized contracts in a court-mediated database, thereby creating an official legal record for each agreement. Furthermore, digital signatures from all contracting parties are verified and recorded on the blockchain, serving as immutable proof of mutual consent. This dual approach ensures that rental contracts are not only legally enforceable but also transparent and verifiable at any time.

4.

Personal Data Vulnerabilities

The system incorporates a privacy-preserving data verification protocol to mitigate risks associated with personal data exposure. During the listing process, landlords may define specific eligibility requirements for prospective tenants. Tenants can then authorize trusted third-party institutions, such as the National Taxation Bureau (NTB), to verify their qualifications (e.g., income level) without disclosing the underlying raw data to the landlord. This consent-based mechanism allows tenants to retain control over their sensitive information while providing landlords with verifiable attestations of their credentials. Consequently, the system significantly reduces the risk of personal data leakage and misuse.

5.2. Experimental Evaluation

5.2.1. Experimental Environment and Methodology

Prior research estimates that approximately 2.45 million individuals in Taiwan require rental housing [2,17], translating to an average demand of five users per minute seeking rental services. Consequently, the proposed system must be capable of scaling efficiently and supporting a high volume of concurrent transactions to ensure smooth and reliable operation under real-world loads.

To evaluate the system’s performance, we deployed the DID Chain using Docker and developed the Rental House Chain with the aid of Fablo, a tool for managing Hyperledger Fabric networks [18]. The hardware specifications of the testing environment are detailed in

Table 13. Computer environment.

CPU	Core	RAM
Intel i5-10400 2.9 GHz (Intel, Santa Clara, CA, USA)	12	16 GB

. To simulate multi-user access and assess the system’s response under stress, we employed Apache JMeter [19] to conduct load testing on the smart contract functions. This approach allowed us to evaluate the system’s capacity to handle a specified number of transactions per second (TPS).

Our performance evaluation primarily focuses on the core operational functions of the Rental House Chain. For detailed performance metrics concerning the DID Chain, including its identity verification efficiency and cryptographic overhead, readers are referred to Section 6.2 of our prior work [10].

To systematically assess performance, we measured the throughput of various smart contract functions, categorized by their parent smart contract. Furthermore, each function was classified into one of two operation types: read operations (i.e., querying blockchain data without altering state) and write operations (i.e., submitting transactions that modify the blockchain state). This distinction facilitates a more granular analysis of system performance, enabling a direct comparison of execution efficiency between data retrieval and state-modifying transactions.

5.2.2. Performance of the Estate Register Contract

The Estate Register contract encompasses two primary functions: UploadPersonalEstate, a write operation, and GetEstate, a read operation. The performance results for these functions are illustrated in Figure 20 and Figure 21, respectively.

A key observation is that the maximum throughput for the UploadPersonalEstate (write) function is approximately 100 transactions per second (TPS), which is substantially lower than that of the GetEstate (read) function. This performance disparity is characteristic of blockchain systems, underscoring that on-chain read operations are generally more computationally efficient and thus achieve higher throughput than write operations, which require consensus and state changes.

5.2.3. Performance of the Estate Agent Contract

The functions within the Estate Agent contract are categorized into read and write operations. Read operations include GetAgentCertificate and GetAgentEstate, whereas write operations comprise NewAgent, AddEstate, AcceptEstate, and RejectEstate.

The implementation of these write functions employs two distinct methods. The NewAgent function is executed via the SDK. In contrast, AddEstate, AcceptEstate, and RejectEstate utilize an Offline Sign mechanism. In the Offline Sign approach, the transaction is first signed on the client side using the user’s private key, which is never exposed to the server. The resulting signed transaction is then transmitted to the server, which is responsible for its submission to the blockchain network. This methodology is designed to minimize the latency of interactive data exchanges, as the server’s role is confined to transaction relay.

Figure 22 and Figure 23 present the transaction throughput results for these write operations. The results indicate no significant disparity in throughput between the SDK-based and Offline Sign methods. This finding suggests that the choice of the implementation method—whether via the SDK or Offline Sign—does not constitute a primary performance determinant for this contract.

5.2.4. Performance of the Estate Publish Contract

The performance evaluations of the Estate Publish contract focused on two critical functions: NewListing and GetAllOnlineListing.

The NewListing function, executed via the Offline Sign method, enables landlords or authorized agents to publish rental properties to the blockchain. As illustrated in Figure 24, this function represents a primary performance bottleneck for write operations, achieving a maximum throughput of approximately 87 transactions per second (TPS). This result underscores the computational overhead associated with on-chain write operations.

The GetAllOnlineListing function facilitates a central read operation, allowing users to query and browse all available rental listings. Given its importance for user interaction, this function retrieves and returns a comprehensive list of properties published on the platform. The testing methodology for GetAllOnlineListing was distinct from previous evaluations; it specifically examined the correlation between the volume of retrieved data and the function’s response time. The test involved executing 10 separate queries for each data size category and calculating the average response time. The results of this analysis, depicted in Figure 25, provide insight into the system’s read efficiency at scale.

Performance analyses of the GetAllOnlineListing function reveal a linear relationship between response times and the number of retrieved rental listings. As the volume of returned data increases, the response time increases proportionally. Specifically, retrieving 20,000 records incurred a response time of approximately 5.656 s, a latency that could noticeably degrade user experience.

To mitigate this performance bottleneck, two optimization strategies are proposed—caching and paginated access:

• Caching: This strategy involves temporarily storing frequently accessed data on the application layer, thereby minimizing direct queries to the blockchain for repeated searches. This approach can significantly reduce response times by serving requests from a faster local cache.
• Paginated Access: This method limits the number of records returned in a single query. By employing bookmarks to track the last accessed item, the system enables efficient navigation through large datasets without overwhelming the user or the backend infrastructure.

To validate these strategies, a test scenario was conducted with 100 concurrent users, each requesting 100 records. This optimized approach reduced the average response time to 1.433 s, a duration considered acceptable for most interactive applications. These findings demonstrate that caching and pagination are effective strategies for enhancing the scalability and responsiveness of read-intensive operations within the blockchain-based rental platform.

5.2.5. Performance of the Rental Agreement Contract

The Rental Agreement contract encompasses three primary functions: CreateAgreement, SignAgreement, and VerifyAgreementSign. The CreateAgreement and SignAgreement functions are implemented as direct on-chain write operations. In contrast, VerifyAgreementSign interacts with the Estate Publish contract by invoking an external write function.

As illustrated in Figure 26, the throughput of VerifyAgreementSign significantly surpasses that of both CreateAgreement and SignAgreement. This result is noteworthy, as VerifyAgreementSign executes a cross-contract call yet demonstrates superior transaction processing efficiency. This performance differential suggests that VerifyAgreementSign is highly optimized, potentially due to more efficient internal logic or lower computational complexity relative to the other two functions.

5.2.6. Performance of the Access Control Manager Contract

The Access Control Manager contract encompasses two core functions, UpdatePermission and GetPermission, both of which were evaluated for throughput performance. The UpdatePermission function facilitates a write operation, utilizing an offline signing mechanism to securely commit permission data to the ledger. In contrast, GetPermission is a read operation designed to retrieve access rights information.

The respective throughput results for these functions are presented in Figure 27 and Figure 28. These findings provide insights into their operational efficiency and scalability within the system’s access control framework.

5.2.7. Experimental Conclusion

The aggregated results of both read and write operations are presented in Figure 29 and Figure 30, respectively. Analyses of the performance data indicate that the system consistently achieves a throughput exceeding 200 transactions per second for read operations and a minimum of 70 transactions per second for write operations.

These results confirm that the system meets the target performance benchmark—defined initially as supporting five users per minute—while maintaining low-latency performance throughout the testing process.

Overall, the findings suggest that the Rental House Chain system is capable of stable and efficient operation under the current test conditions, rendering it suitable for real-world deployment scenarios with comparable demand levels.

5.3. Related Research Comparison

To evaluate the novelty and effectiveness of our proposed system, we conducted a comparative analysis against several related studies. This comparison was guided by research questions, specifically highlighting key system features and limitations. The results of this comparative analysis are summarized in

Table 14. Related research comparison.

	Our Research	Sanskar Sharma et al. [4]	Laila Junaid et al. [7]	João F. Santos et al. [11]
Blockchain	Hyperledger Fabric	Ethereum	Ethereum	Hyperledger Fabric
Identity and property authentication	Use DID Chain and DLA authentication	Soulbound Tokens trace identity	A specific Property Identification Number (PID)	Registration with the CA
Transparency	Blockchain architecture	Blockchain architecture	Blockchain architecture	Blockchain architecture
Lease protection	Contracts and signatures are recorded on the blockchain through the court	Rent control through smart contracts	△	△
Personal data sharing vulnerabilities	After authorization, verification is performed by a credible third party	X	X	Tenants upload files and authorize sharing
Other features	Can entrust real estate agents; private keys are under personal control, DID Chain	Reputation and review	Combined with a blockchain-based mortgage to prevent double-spending	The system generates audit reports

.

In Table 14, the symbol △ denotes aspects that are not explicitly addressed in the corresponding studies but that are deemed potentially valuable within the context of our research objectives. This symbolic notation helps identify areas where related studies may benefit from future enhancements that are aligned with our system’s design.

There are two symbols in the comparison table with the following definitions:

△ (Triangle Symbol): The triangle symbol “△” indicates an aspect that is not explicitly mentioned or addressed in a particular related research publication but is considered to have potential benefits in this study.

X (Cross Symbol): The cross symbol “X” indicates that the related research publication does not cover or address a specific function or issue.

Table 14 provides a detailed comparison of our proposed system with three representative blockchain-based rental systems: Sharma et al. [4], Junaid et al. [7], and Santos et al. [11]. This comparison focuses on several core functional aspects, including the underlying blockchain platform, identity and property authentication mechanisms, data transparency, lease protection, and personal data sharing protocols.

Our system utilizes Hyperledger Fabric, a permissioned ledger that provides both decentralized trust and enterprise-grade governance and privacy controls. In contrast, the other studies rely exclusively on either Ethereum [4,7] or Hyperledger Fabric [11], a choice that may limit either public verifiability or granular access control.

Regarding identity and property authentication, our system introduces a novel mechanism that integrates a Decentralized Identifier (DID) Chain with verification by the Department of Land Administration (DLA). This dual-layered approach establishes government-backed trust and enhances reliability. While other systems employ different strategies—such as Soulbound Tokens for identity tracing [4], a Property Identification Number (PID) [7], or Certificate Authority (CA) registration [11]—these methods, though effective to an extent, lack the robust, multifaceted authentication framework afforded by our DID and DLA integration.

Transparency is a common benefit achieved across all compared systems via their underlying blockchain architecture, which ensures data immutability and traceability. However, our study enhances this foundational transparency by also recording entrustment relationships, digital signatures, and court-verified rental contract records on-chain.

In terms of lease protection, our system explicitly stores contracts and digital signatures on the blockchain and engages the court as a verification authority to ensure legal enforceability. While Sharma et al. [4] incorporate rent control mechanisms via smart contracts, the other two systems [7,11] lack explicit mechanisms for lease protection, as indicated by the △ symbol in our comparison.

To address personal data sharing vulnerabilities, our approach employs a privacy-preserving verification protocol where third-party entities (e.g., NTB) conduct data verifications only with explicit tenant authorization. This design adheres to the principles of data minimization and confidentiality. Conversely, the systems by Sharma et al. [4] and Junaid et al. [7] do not detail secure data sharing mechanisms, while Santos et al. [11] permit direct file uploads by tenants, a method that could introduce privacy risks without robust security measures.

Finally, our system provides several distinct features, including agent entrustment functionality, user-controlled private keys, and robust identity management via its DID Chain. These features afford users greater autonomy, traceability, and trust compared to the other systems, which focus on alternative aspects such as reputation systems [4], mortgage-related protections [7], or audit report generation [11].

6. Conclusions and Future Research

6.1. Conclusions

This study presents a blockchain-based architecture for a rental housing system designed to enhance trust, guarantee personal data privacy, and address critical inefficiencies within the rental market. The proposed system facilitates secure and transparent interactions among landlords, real estate agents, and tenants by resolving persistent challenges, including unverifiable property listings, market opacity, inadequate lease protection, and vulnerabilities in personal data management.

To address identity and property verification, the system integrates a Decentralized Identifier (DID) Chain with verification protocols from the Department of Land Administration (DLA). This dual mechanism ensures that both user identities and property ownership are authenticated prior to registration. All rental-related transactions and records—such as property listings, agency authorizations, and contractual agreements—are immutably stored on the blockchain, thereby enhancing traceability and guaranteeing data integrity.

The system further ensures the legal enforceability of rental contracts by incorporating court-mediated validation and storage. Rental Agreements are executed via digital signatures and securely recorded on-chain, providing cryptographic proof of consent among all contracting parties.

To mitigate privacy risks, the architecture enables third-party verification of sensitive information, such as tenant income, without disclosing raw data to landlords. This is achieved through a blockchain-based access control mechanism that facilitates verifiable, consent-based data sharing. All blockchain interactions are authorized via offline signatures, ensuring that users’ private keys remain under their exclusive control and are never exposed to the network. The architecture also supports the delegation of rental management to authorized real estate agents, reflecting practical market scenarios and enhancing system usability.

Performance evaluations demonstrate that the system achieves a throughput sufficient for real-world rental demands, processing requests at a rate exceeding five users per minute. These results confirm the system’s viability as a secure, scalable, and trust-enhancing platform for the rental housing market.

6.2. Future Research

Despite its foundational capabilities, the current system exhibits several limitations when compared to real-world rental market dynamics. The architecture is presently constrained to one-to-one property and rental relationships, which preclude the subdivision of a single property into multiple rental units. This constraint renders the system unsuitable for more complex scenarios, such as shared housing or multi-tenancy buildings, which are commonplace in modern rental markets. A critical direction for future research is to support subdivided rental units while preserving the same degree of trust and accountability for each individual lease.

Further limitations exist in agent and commission management. While the system facilitates lease authorization by real estate agents, it does not yet incorporate mechanisms for managing commission contracts or tracking payments. Moreover, the current design restricts subletting authority to certified real estate agents, excluding uncertified individuals from managing sublets. Future iterations should aim to support subletting by non-certified parties to better reflect diverse market practices.

A significant limitation is the absence of automated legal reviews for rental contracts. Currently, contracts submitted to the court-mediated module are not assessed for legal compliance. Future studies will focus on integrating AI-based analytical tools to automatically identify potentially non-compliant or unlawful clauses, thereby enhancing the system’s legal reliability. This enhancement would move the process closer to a digitally notarized model, offering superior legal protection for all contracting parties.

The system’s capabilities could also be extended through integration with external entities. Collaboration with financial institutions, for instance, could enable automated, contract-driven payment execution, streamlining rent collection and improving transactional efficiency. Establishing partnerships with additional trusted third-party verifiers would further bolster support for complex rental arrangements and increase the robustness of personal data validation.

Addressing these limitations represents key avenues for future research and development. By tackling these challenges, the system can evolve into a more comprehensive, adaptable, and robust platform aligned with the nuanced demands of real-world rental ecosystems.