Enhancing Blockchain Interoperability Through Cross-Chain Outsourcing and Communication Shiming Duan Faculty of Information Technology City University Malaysia Kuala Lumpur, Malaysia duan_shiming@qq.com M. Kazem Chamran Faculty of Information Technology City University Malaysia Kuala Lumpur, Malaysia ORCID: 0000 0003 3836 4443 Mustafa Muwafak Alobaedy Faculty of Information Technology City University Malaysia Kuala Lumpur, Malaysia new.technology@hotmail.com Abstract—The shortcomings of blockchain technology, previously concealed, are now known to specialists and academics as blockchain technology has grown in popularity. The most basic idea at the heart of centralized technology is interoperability, but connecting interoperation with blockchain will trigger more challenges. The fundamental cryptography of blockchain technology causes issues with interoperation across connected blockchains. Scholars are continually working on solutions for cross-chain operations from blockchain birth till now. Some of these measures ensure that tokens are equivalent to one another. Some of them rely on side-chain technology, and some of them rely on centralized trading centers. However, will the new solution be able to gather the experience of its predecessors and build a more complete blockchain crosschain interoperability scheme? Is it feasible to create a global platform for cross-chain operations that would enable the interoperability of common blockchain features and provide solutions for the interoperability challenges posed by nonuniform aspects? This study strives to investigate the solution and viability of the solution using the action research approach by combining the papers and reports of earlier researchers. Finally, this paper proposes an easier-to-use cross-chain interoperability framework by synthesizing the experiences of previous scholars. Results show that this framework is the easiest to extend and interface. This framework can support cross-chain operations for all kinds of blockchain. Keywords—framework, operations, decentralized ledger technology I.INTRODUCTION Blockchain was defined as a tool for distributed accounting and data consistency [ 1 ]. The creators of blockchain describe the first decentralized ledger as a ledger where everyone is anonymous and can write something without control. A single or federated entity does not control the ledger and allows anyone to write to it. Blockchain ecology exists in many blockchains, such as Ether [ 2 ], Ripple [3], and others. Blockchain Explorers lists 171 active blockchains as of July 2023 [4]. A prominent application of distributed ledger is blockchain technology, which must possess many of the technical characteristics of Distributed Ledger Technology (DLT), such as decentralization, openness, invariance, transparency, traceability, security, and availability. In addition to some of the characteristics of decentralized technology such as consistency, availability, tolerance to network partitioning. However, with the advanced development of blockchain technology, some of its features have gradually become limitations. For example, cross-chain transactions and multi-chain collaborative work are functionalities that are gradually evolving with blockchain technological advancements[ 5 ]. With the development of blockchain technology, continuous researchers are trying to find ways to solve the contradiction between blockchain features and applications [6]. Blockchain has gone beyond digital currencies and enabled smart contracts, entering the realm of decentralized transaction management systems with distributed databases through many other forms of decentralized collaboration [ 7 ][ 8 ]. Due to the existing limitations, developing decentralized networks, producing decentralized applications, and autonomous organizations will be trendy subjects during the next ten years. The capacity of distributed ledger technologies like blockchain to interface and connect with other systems will determine their future [ 9 ]. These developments present the software development industry with new chances and problems [4]. With the development of technology, blockchain technical innovations have appeared and improved. Part of the blockchain has applied to business. Transaction rules, Smart Contracts, and data models of the blockchain network are specifically on a particular application. When it is necessary to interconnect different business blockchains with multiple models, interchain communication needs through cross-chain interoperability technology [ 10 ][ 11 ][ 12 ][ 13 ][ 14 ]. Developing blockchain interoperation systems remains a complex challenge, regardless of the solution employed. This paper proposes Enhancing Blockchain Interoperability Through Cross-Chain Outsourcing and Communication, a framework that focuses on cross-chain transactions and combines them with notarized collections to achieve transaction assurance. Through theoretical analysis and simulation in a laboratory environment, it is simple to realize the transmission of information between blockchains. The framework does not require any modification of the original blockchain to realize inter-blockchain communication and interoperability, and the information transmitted by inter-blockchain interoperability will not be subject to any restriction. A. Research Scope Some existing blockchain interoperability techniques involve modifying the original blockchain itself. This may require a fork (creating a new blockchain), updating the 979-8-3503-5385-3/24/$31.00 ©2024 IEEE276 2024 IEEE 6th Symposium on Computers & Informatics (ISCI) | 979-8-3503-5385-3/24/$31.00 ©2024 IEEE | DOI: 10.1109/ISCI62787.2024.10668062 Authorized licensed use limited to: UNIVERSITY TEKNOLOGI MALAYSIA. Downloaded on September 22,2024 at 12:20:09 UTC from IEEE Xplore. Restrictions apply. underlying code, or implementing specific rules to enable the blockchains to connect. These techniques could be potential security issues associated with this approach [15]. Hence, the existing blockchain ecosystem needs a framework that enables interoperability between blockchains without destroying or modifying the original blockchain on the premise. B. Significance of Research 1. Creatively adopt a novel method to establish the blockchain interoperability framework without changing the original blockchain code. 2. Reduce the complexity of the traditional blockchain interoperation framework through a transaction-based approach. With the core goal of completing cross-chain transactions, this research utilizes the outsourcing concept of blockchain and adopts outsourcing to realize cross-chain interoperation. The program improves some of the functions of the entire blockchain technology ecosystem to a certain extent. Its main realization goal is that users only need to spend a small number of tokens to realize cross-chain interoperability. 3. Users decide the value of building blockchain interoperability behavior. The framework empowers the user community with the autonomy to define the value of tokens and smart contracts [16]. II. METHODOLOGY This action research study analyzes the entire problem of blockchain interoperability. It combines theory, current research, and practical application in a cyclical process to develop a generic and achievable framework for blockchain interoperation. This method considers the current research landscape and utilizes a spiral approach to assess the potential of blockchain interoperability solutions. A. Research Initialization To explore the potential of blockchain interoperability, we need to analyze the current state of research. This research aims to analyze blockchain interoperation by surveying 25 relevant publications from 2018-2023. Fig.2 illustrates the frequency of keywords used in these articles. Fig.2 shows that the keywords centralized ledger, crossblockchain communication, and interoperability occupy the top three places in the sample. Therefore, most blockchainrelated researchers focus on the direction of communication and interoperation between blockchain ecosystems. Fig.2 Keyword Frequency B. Research Analysis This study demonstrates the possibility of blockchain interoperability by combining the current status quo with the theory and starting with the blockchain interoperability foundation problem in a circular process. After analyzing the current situation, the blockchain interoperability framework is being built. Such as the cross-chain interoperation framework must guarantee transaction consistency, security, and anonymity. A higher-level requirement is to require cross-chain interoperability framework generalization. C. Proposed Interoperability Framework This research aims to achieve blockchain interoperability with minimal disruption to existing blockchain structures, leveraging mature technologies while promoting their use cases and models. This approach increases the framework's practicality and real-world applicability. The proposed framework transforms continuous interoperability transactions into atomic transactions with repeated confirmations. This essentially establishes a persistent connection between two blockchains through repeated account verification, ensuring atomicity and overall transaction security. For widespread blockchain interoperability, this research prioritizes optimizing the flexibility of blockchains within the ecosystem. This means any blockchain, including multi-ledger ones, should be able to autonomously adopt a cross-chain interoperability technology. However, to emphasize the overall framework's innovation, some technical details are not addressed in this proposal. D. Framework Expected Features Blockchain technical characteristics limit their ecology. This research is intended to break the status quo of difficult interoperability between blockchains by building a blockchain interoperability framework with public interfaces. Building a more inclusive blockchain framework to provide interoperability between blockchains is not enough. Every blockchain has a set of potential risks. Tighter constraints on this more inclusive blockchain framework are needed, such as hot-plugging and fusion features. Hot-plugging provides immediate support for cross-chain transactions when they occur. When there is no cross-chain transaction, it can keep the cross-chain transaction from affecting the other blockchain. The fuse feature is to defend the risk of a blockchain from causing a chain crisis in the blockchain ecosystem. The clearinghouse is the most instantaneous and technologically segregated way to achieve cross-chain token conversion and interoperability. Transaction centers, however, potentially carry additional dangers. For instance, transaction centers do not ensure the anonymity of crosschain token conversions, some of which bring about credit risk, which goes against the decentralization premise. To achieve universal applicability and simultaneously address the hazards brought on by the token trading center, it is thus possible to develop a cross-chain operating framework comparable to the trading center. Cross-chain interoperability frameworks with similar functions as trading centers need to consider both centralized and decentralized architectural modes when making technology selections, where centralized architecture has clear advantages in processing efficiency, management 277 Authorized licensed use limited to: UNIVERSITY TEKNOLOGI MALAYSIA. Downloaded on September 22,2024 at 12:20:09 UTC from IEEE Xplore. Restrictions apply. efficiency, and scalability, and decentralized architecture has extremely high advantages in autonomy, security, transparency, and innovation. A more specific comparison of the advantages and disadvantages is shown in Fig. 3. Fig. 3 Centralization framework and Decentralization framework SWOT Analysis III. RELATED WORK This section focuses on the structure, modules, operation flow, features of the outsourcing framework, and the differences from other blockchain cross-chain interoperability schemes. A. Architecture of Outsourcing Framework The eight modules shown above make up most of the core functionality of a cross-chain interoperable blockchain. Fig. 4 shows the technical architecture of the outsourced blockchain framework. It includes the transactions request module, user account module, transaction in progress module, contract storage module, transaction pending confirmation module, investor module, transaction confirmation module, and proof of work module. These modules are the basic modules of the outsourced cross-chain framework. Fig. 4 Outsourcing Blockchain Functional Modules The User Account Module keeps track of how many tokens each user has in this blockchain and stops hostile users from sending transaction applications frequently to assault the entire outsourcing blockchain platform. The Contract Storage Module stores the judge's contracts, which holds most contracts used for executing the contract, performing encryption techniques and decryption, revenue distribution methods, and other operations on specific blockchains using invisible address techniques. Cross-chain interoperation framework can choose from the smart contracts in this section to help complete the process of transferring accounts between blockchains. According to the demands of applicants for cross-chain interoperation, the Investor Module is for one or more investors to complete the investment of the target transaction. The Proof of Work Module serves as the miner's evidence of workload. Transaction Request Module collects all transaction requests and several dates of the framework. The procedure is when an investor has already accepted the transaction submitted by the application but hasn't been recorded on the chain by the following miner and disposed of by the Transaction in Progress Module. A transaction in the Transaction in Progress Module is known as the Transaction Pending Confirmation Module. In this transaction, the miner first verifies the transaction for the amount on both accounts but does not yet decode the whole transaction. In a transaction called a "Transaction Confirmation Module, " the miner swaps the accounts of the two parties after reconfirming the balances of the accounts in the original and target blockchain. Fig. 5 depicts the overall organization of the blockchain links and includes coin minting transactions and cross-chain application transactions, order-taking transactions, and confirmation transactions. The cross-chain interoperability transaction needs the following data application fee, maximum value of each investor's investment, number of target tokens required, number of invested original tokens, number of confirmations, and other crucial details. When the 278 Authorized licensed use limited to: UNIVERSITY TEKNOLOGI MALAYSIA. Downloaded on September 22,2024 at 12:20:09 UTC from IEEE Xplore. Restrictions apply. number of confirmations achieves the number suggested by the applicant, this transaction will finish. Each transaction includes confirmation of transactions that have already been down. Fig. 5 The structure of "outsourcing" blockchain B. Practical Operation Procedure of Outsourcing Framework As a revolutionary cross-chain interoperability framework, the "outsourcing" framework made by "outsourcing" blockchain, its structure and functionality allow each blockchain's expansion as a plug-in, it will reduce the impact on both the target and original blockchain. As a result, the architecture and execution of "outsourcing" need to be creative and reasonable. The "outsourcing" blockchain functions as follows in practice: Fig. 6 shows the actual process of outsourcing framework to achieve interoperability. A user from the original blockchain submits a request for a cross-link operation in the outsourcing blockchain. The outsourcing framework records and publicizes such a request in the links of the outsourcing blockchain. Once a sponsor is interested in the transaction, the outsourcing framework will get a reply. Investors and judges are responsible for transaction security and transaction implementation. The cross-chain token exchange is an example in Fig.6. When other scholars make some improvements, this framework can provide a wide range of support. In Fig. 6. the seven cross-chain operation phases shown “Application Step", "Interoperability Application Step”, “Transfer Step", "Checking Step", "Checking Result Judgment Step", "Interoperability Step", and "Successful Transaction" sum up the process of outsourcing framework. The foundation of the entire cross-chain process consists of these phases. While combining with other technologies, this framework will create a more scalable interoperability technology platform based on these technologies. Every stage of the interoperation transaction must have its data integrity and consistency checked to guarantee the atomicity of the whole transaction. Any problem with any of the events that would affect the atomicity of the transaction will abandon the interoperable transaction. Fig 6 The "outsourcing" framework functions "Application Steps": The application steps are mainly for the applicants to upload their requirements, including the target chain, exchange ratio, operation content, and other data using the cross-chain operation to the "Outsourcing" blockchain. The miners on the outsourcing blockchain will collect these requirements and upload them to the chain. The applicant can use the smart contract if it exists in the "Outsourcing" blockchain to bind the tasks and responsibilities of both parties to the transaction. "Interoperability Request Step": the interoperability request step is that after the miner has uploaded the applicant's transaction request, the investor on the "outsourcing" blockchain will check its conditions and compare them with the requirements, and if it agrees with the transaction, it will send a request to the blockchain to agree with the transaction, and at the same time, the miner will also need to request the "outsourcing" blockchain. If the investor approves the transaction, they will send the request to the "outsourcing" blockchain to agree to the transaction. If no investor approves of the transaction, give a request back for the failed transaction after a certain period. The transaction is marked as a failure from the entire "outsourcing" blockchain, preventing subsequent miners from continuing to record and track the transaction. "Transfer Step": This step assumes that there are investors and that they are willing to complete the deal. 279 Authorized licensed use limited to: UNIVERSITY TEKNOLOGI MALAYSIA. Downloaded on September 22,2024 at 12:20:09 UTC from IEEE Xplore. Restrictions apply. Create one-time accounts for investors and applicants through stealth address technology and smart contracts that allow them to communicate with each other on a dual chain blockchain. These accounts will expire after the address has taken effect. "Account Checking Step": the application, investor, contract maker (judge), and miner review the two accounts after the miner uploads the records of successful transfers to the chain. To the greatest extent possible, this kind of account verification can guarantee the security and equity of the entire transaction. "Judgement Step of Checking Result": Generally speaking, there are two ways to determine the outcome of a check. If the tokens are missing from the one-time account, the transaction will fail and smit the offending party. It moves on to the next phase if it is successful. "Interoperability Step": Decryption is the initial step in the interoperability phase. The step in the interoperability process is to decrypt the one-time address created by the address-hiding technique, which applies to receiving payments. Hence, the decryption process releases the account's private key, which is one way to ensure the security and atomicity of the entire transaction. "Successful Transaction": To guarantee data integrity, miners must uplink this data, which is the last signal of a single transaction. C. Framework Role Flow Outsourcing Roles in the "outsourcing" framework include applicants, miners, judges, and investors. Since the "Applicant" started the entire cross-chain interoperability transaction, all other roles are centered around the "Applicant" during the transaction. As the one who realizes cross-chain interoperability, the "investor" is motivated to act by the opportunity to get a fee for each transaction. Since 171 active blockchains and acquired tokens are mostly among these mainstream tokens, the "investor" is typically indifferent to the type of token obtained. Depending on how much labor they put in, miners who upload different types of data into the blockchain will get a portion of the earnings after the transaction. The "Judge" oversees establishing regulations for cross-chain transactions and has the authority to determine the price based on how automated and secure the rules are. After each transaction, it must pay for the judge, who will also oversee the entire transaction process. The framework is trying to split a cross-chain transaction into countless smaller transactions. Follow the steps in this framework design to gradually release bidirectional from one blockchain to another. Data security is accomplished at the technical level by the cross-chain encryption algorithm released by the judge in the outsourced blockchain. In the process of hacking, most of the hacker's computing power needs to be stronger than that of a single node with a decryption algorithm. According to this feature, if the split sub transaction is small enough during the cross-chain transaction splitting process (the cost of hacking a single sub transaction is significantly higher than the value of the single sub transaction). From a logical point of view, the benefits of hacking the entire cross-chain transaction are very tiny. In the experimental stage like Fig. 7, the framework divides a single transaction into multiple sub transactions, adds time locks to the mix of these sub transactions, and performs oneto-one mapping. This process takes place once for each side of the cross-chain transaction. Then, according to the process, the mapping results are exchanged separately under the multi-role notary and the return receipt. The whole process needs at least n+1 times. The last time of communication is the mapping parameters. The advantage of this encryption is that it guarantees that both parties can obtain most of the subsets after the transaction. Fig. 7 encryption and decryption transfer process D. Cross-Chain Methods Differences A mass of cross-chain methods focused on changing the blockchain's underlying architecture to include new field limitations or creating new kinds of blockchain structure. By mass minting coins and locking the existing blockchain's coins, destroy the original blockchain's coins to interoperate the new blockchain. Therefore, the running Bitcoin and Ether blockchains and other similar blockchain products are already mature and robust blockchains. Most existing crosschain operation techniques require minor changes to the target chain, such as locking the tokens and other operations. As a result, such an operation may increase the potential risks. A subset of people now achieve blockchain interoperability through trusted agents [ 17 ][ 18 ]. Some portion uses hash locks [19], sidechains, and atomic swaps [20] to achieve interoperate. The literature [21] gives an analysis of blockchain interoperability and proves that blockchain interoperability is difficult. Currently, blockchains commonly use token exchange to achieve interoperability. The framework has the following features: 1) Public Links Many blockchain developers should aim to concentrate on enhancing their blockchain ecosystem to the best of their abilities rather than thinking about how their blockchain will interact with other blockchains. Cross-chain technology or cross-chain technology framework providers will carry out the responsibilities of cross-chain interoperation. To achieve the interoperation of many distinct blockchains, development at this point must thus have the features of public linkages. 2) Isolation Between Blockchains The impact on the native blockchain must be negligibly tiny, and it is optimal if there is no impact. Since the entire quantity of all blockchain tokens in each blockchain is known, creating, and destroying new tokens affects 280 Authorized licensed use limited to: UNIVERSITY TEKNOLOGI MALAYSIA. Downloaded on September 22,2024 at 12:20:09 UTC from IEEE Xplore. Restrictions apply. blockchain interoperability and significantly affects each bl ockchain's financial characteristics. The danger of threat rises substantially as a power function if everyone chooses one way to destroy and create blockchain tokens. In addition, there are few methods to demonstrate that actions will affect the blockchain in the first place or only have uncontrolled effects later. 3) Users Determine Redemption Criteria The blockchain token is a vital part of the blockchain and needs to follow the rules of distribution. Distributed technology is a point-to-point way of transmitting information, and no center can define the value of tokens. Many cross-chain activities aim to lower the token exchange rate that occurs across the chain. However, the token exchange ratio demonstrates the worth of a token. As an illustration, the market capitalization of Bitcoin changes over time, and the price of Bitcoin tokens will change every day. So, the token exchange rate and transaction fee are an expression of the value of the blockchain, making the use of a dynamic exchange rate and transaction charge a viable option. For user operations that perform cross-chain, each user has the right to define the value corresponding to its interoperation behavior. In other words, every user can delimit how much to pay for their cross-chain interoperation. IV. RESULTS AND DISCUSSION Compared with the original cross-chain interoperability technology, this solution, based on a composite of several more mature and secure cross-chain technologies, carries out technological innovations and integration of these technologies. In this study, the users of each blockchain autonomously decide the exchange rate for token exchange and the value of the cross-chain operation function. This study's technique divides the original physical link into two virtual links, enhancing data security and making it more challenging for unauthorized users to attack each blockchain. The technology is a universal arbitrary blockchain token that can operate across the chain with the consent of both users. A. Conclusion This research investigates the importance of cross-chain interoperability through two analysis phases. It then employs a practical method, leveraging semi-automatic techniques like outsourcing, to demonstrate the feasibility of achieving interoperability. To address this challenge, the research proposes a technological framework that incorporates the core principles of distributed applications and crowdfunding. This framework aims for broad applicability, exceeding the limitations of existing solutions. However, due to time constraints, some framework modules rely on standard cryptographic methods, potentially limiting their application in certain scenarios. This framework presents a novel approach to blockchain interoperability, although further development with cryptographic expertise could enhance its comprehensiveness. It provides a valuable foundation for future research to address cross-chain communication. 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