For the goals of security and privacy preservation,we propose a blind batch encryption-and public ledger-based data sharing protocol that allows the integrity of sensitive data to be audited by a public ledger and all...For the goals of security and privacy preservation,we propose a blind batch encryption-and public ledger-based data sharing protocol that allows the integrity of sensitive data to be audited by a public ledger and allows privacy information to be preserved.Data owners can tightly manage their data with efficient revocation and only grant one-time adaptive access for the fulfillment of the requester.We prove that our protocol is semanticallly secure,blind,and secure against oblivious requesters and malicious file keepers.We also provide security analysis in the context of four typical attacks.展开更多
This article outlines the benefits and risks of the distributed ledger technology(DLT)for the clearing and settlement of exchange-traded and OTC securities,followed by a description of the technology’s potential role...This article outlines the benefits and risks of the distributed ledger technology(DLT)for the clearing and settlement of exchange-traded and OTC securities,followed by a description of the technology’s potential role for central counterparties and central securities depositories.Although the industry and scholars are attempting to solve the technological and operational issues that DLT systems still face,outstanding legal risks are such that the financial industry is asking for more regulatory guidance and intervention.This article wants to contribute to the public policy debate by presenting potential regulatory barriers that may have to be removed for DLT to be fully adopted.In addition,it identifies areas requiring an update of the legal framework in order to address certain prudential and conduct risks that this technology could introduce.展开更多
As one of the most concerned digital technologies in recent years,blockchain and distributed ledger technology are an important driving force for a new round of technological development.It is currently in the process...As one of the most concerned digital technologies in recent years,blockchain and distributed ledger technology are an important driving force for a new round of technological development.It is currently in the process of accelerating its evolution and maturity,and has gradually integrated with other digital technologies.It has been applied in many industries,providing decentralized solutions for various industries,realizing innovative storage models,and building a new trust system.As blockchain technology is officially incorporated into China’s new information infrastructure category,the application fields of blockchain have expanded rapidly,gradually extending from the financial field and government affairs to other fields in the real economy.At the same time,with the continuous development of the globalized economy,blockchain technology will also have a profound impact on international technological and economic development.Therefore,for the healthy and orderly development and real implementation of the blockchain industry,standardize the application of blockchain,effectively break through the cognitive and technical barriers between different countries,industries and systems on a global scale,prevent application risks,the development of the global blockchain industry needs standardization basis,which is particularly important and urgent.A sound standard system is an important key to the successful development of technology,and formulating the right standard at the right time for technology development helps ensure the ease of use and interoperability of the technology.From the perspective of international standardization,this article first introduces the general situation of ISO,ITU-T,IEEE,W3C and other international standardization organizations,and sorts out the status quo of the blockchain standardization working groups of mainstream international standardization organizations.All blockchain-related standards under development have been analyzed for the characteristics of international blockchain technology standards and industry application standards.Through data analysis,the overlaps,differences and conflicts in the field of international blockchain standard formulation are sorted out,and suggestions for blockchain standardization work in the application and development of blockchain technology standardization by international organizations and industries are put forward.The plans and layouts of future international standards are summarized to help the development of the international standardization of blockchain.展开更多
A zero-knowledge proof or protocol is a cryptographic technique for verifying private data without revealing it in its clear form.In this paper,we evaluate the potential for zero-knowledge distributed ledger technolog...A zero-knowledge proof or protocol is a cryptographic technique for verifying private data without revealing it in its clear form.In this paper,we evaluate the potential for zero-knowledge distributed ledger technology to alleviate asymmetry of information in the asset-backed securitization market.To frame this inquiry,we conducted market data analyses,a review of prior literature,stakeholder interviews with investors,originators and security issuers and collaboration with blockchain engineers and researchers.We introduce a new system which could enable all market participants in the securitization lifecycle(e.g.investors,rating agencies,regulators and security issuers)to interact on a unique decentralized platform while maintaining the privacy of loan-level data,therefore providing the industry with timely analytics and performance data.Our platform is powered by zkLedger(Narula et al.2018),a zero-knowledge protocol developed by the MIT Media Lab and the first system that enables participants of a distributed ledger to run publicly verifiable analytics on masked data.展开更多
Election allows the voter of a country to select the most suitable group of candidates to run the government.Election in Pakistan is simply paper-based method but some certain political and socio-economic issues turn ...Election allows the voter of a country to select the most suitable group of candidates to run the government.Election in Pakistan is simply paper-based method but some certain political and socio-economic issues turn that simple process in complicated and disputes once.Solutions of such problems are consisting of many methods including the e-voting system.The e-voting system facilitates the voters to cast their votes by electronic means with very easy and convenient way.This also allows maintaining the security and secrecy of the voter along with election process.Electronic voting reduces the human-involvement throughout the process from start to the end.Such system is not established yet in Pakistan.Hence,every election is disputed always.In this paper we proposed the framework of an e-voting system and simulation with the use of blockchain ledger technology.The proposed framework owns the capacity to deal with ballots in Pakistan.The novelty of the framework is that the e-voting system is linked to National Database and Registration Authority(NADRA)database which assures voter’s validation.The fundamental requirements were kept in consideration during the performance evaluation of the system.The results are processed and depicted specially with reference to the number of voters and voting stations,real time of vote casting,network bandwidth and controlling principles.The results support the decision makers and guide them in the foundation and customization of an e-voting system in Pakistan.展开更多
Privacy-preservation and effective auditing are two desirable but challenging requirements on distributed ledgers. To meet the requirements, this paper presents an auditing scheme, called as AudiTEE, which can audit a...Privacy-preservation and effective auditing are two desirable but challenging requirements on distributed ledgers. To meet the requirements, this paper presents an auditing scheme, called as AudiTEE, which can audit a distributed ledger in a generic, efficient, and privacy-preserving manner. AudiTEE leverages Trusted Execution Environment (TEE) to generate confidential but auditable transactions and realize arbitrary, efficient and confidential audit on them. Unfortunately, TEE suffers from some inherent barriers and is itself not a complete solution for fast audit. To tackle these challenges, AudiTEE takes advantage of KAMT (K-anonymity Authentication Based on Merkle Tree) protocol for efficient management on account and user-defined anonymous transactions. Further, to achieve a complete and fast audit with <i>unlinkability</i>, TEE doesn’t process through all but only a comparatively small part of transactions according to a special <i>ktag</i> attached on each transaction to ensure that a user cannot hide transactions from auditor even when auditor is blind with who is involved in each transaction on the ledger. Apart from the above, AudiTEE allows flexible control on user behaviors. We implement a concrete instance of AudiTEE under a bank setting and demonstrate the scalability with all its core functionalities.展开更多
Due to the advantages of high volume of transactions and low resource consumption,Directed Acyclic Graph(DAG)-based Distributed Ledger Technology(DLT)has been considered a possible next-generation alternative to block...Due to the advantages of high volume of transactions and low resource consumption,Directed Acyclic Graph(DAG)-based Distributed Ledger Technology(DLT)has been considered a possible next-generation alternative to blockchain.However,the security of the DAG-based system has yet to be comprehensively understood.Aiming at verifying and evaluating the security of DAG-based DLT,we develop a Multi-Agent based IOTA Simulation platform called MAIOTASim.In MAIOTASim,we model honest and malicious nodes and simulate the configurable network environment,including network topology and delay.The double-spending attack is a particular security issue related to DLT.We perform the security verification of the consensus algorithms under multiple double-spending attack strategies.Our simulations show that the consensus algorithms can resist the parasite chain attack and partially resist the splitting attack,but they are ineffective under the large weight attack.We take the cumulative weight difference of transactions as the evaluation criterion and analyze the effect of different consensus algorithms with parameters under each attack strategy.Besides,MAIOTASim enables users to perform largescale simulations with multiple nodes and tens of thousands of transactions more efficiently than state-of-the-art ones.展开更多
In recent years,blockchain technologies have expanded from the finance field to other areas that rely on trustbased solutions.The healthcare industry represents one such area,as digital transformation disrupts relatio...In recent years,blockchain technologies have expanded from the finance field to other areas that rely on trustbased solutions.The healthcare industry represents one such area,as digital transformation disrupts relationships between patients,healthcare professionals,and healthcare institutes.Patients and healthcare institutes lack a proficient tool to verify the credentials of medical professionals in a digital environment.Furthermore,healthcare professionals lack a tool where they are in control over their credentials.The first contribution of this paper is a proposal of a solution that leverages the private permissioned Hyperledger Fabric blockchain and smart contracts to provide a source of transparent trust for relationships within the healthcare industry.Second,we pave the ground for GDPR compliance by storing only the hash values on the blockchain.Third,we solve the problem of patient authentication by utilizing cryptographic techniques.Finally,we prove the usability of the proposed solution by implementing a user interface and creating a live deployment.展开更多
A key component of blockchain technology is the ledger,viz.,a database that,unlike standard databases,keeps in memory the complete history of past transactions as in a notarial archive for the benefit of any future te...A key component of blockchain technology is the ledger,viz.,a database that,unlike standard databases,keeps in memory the complete history of past transactions as in a notarial archive for the benefit of any future test.In second-generation blockchains such as Ethereum,the ledger is coupled with smart contracts,which enable the automation of transactions associated with agreements between the parties of a financial or commercial nature.The coupling of smart contracts and ledgers provides the technological background for very innovative application areas,such as Decentralized Autonomous Organizations(DAOs),Initial Coin Offerings(ICOs),and Decentralized Finance(DeFi),which propelled blockchains beyond cryptocurrencies that were the only focus of first generation blockchains,such as Bitcoin.However,the currently used implementation of smart contracts as arbitrary programming constructs has made them susceptible to dangerous bugs that can be exploited maliciously and has moved their semantics away from that of legal contracts.We propose here to recompose the split and recover the reliability of databases by formalizing a notion of contract modeled as a finite-state automaton with well-defined computational characteristics derived from encoding in terms of allocations of resources to actors,as an alternative to the approach based on programming.To complete the work,we use temporal logic as the basis for an abstract query language that is effectively suited to the historical nature of the information kept in the ledger.展开更多
基金partially supported by the National Natural Science Foundation of China under grant no.62372245the Foundation of Yunnan Key Laboratory of Blockchain Application Technology under Grant 202105AG070005+1 种基金in part by the Foundation of State Key Laboratory of Public Big Datain part by the Foundation of Key Laboratory of Computational Science and Application of Hainan Province under Grant JSKX202202。
文摘For the goals of security and privacy preservation,we propose a blind batch encryption-and public ledger-based data sharing protocol that allows the integrity of sensitive data to be audited by a public ledger and allows privacy information to be preserved.Data owners can tightly manage their data with efficient revocation and only grant one-time adaptive access for the fulfillment of the requester.We prove that our protocol is semanticallly secure,blind,and secure against oblivious requesters and malicious file keepers.We also provide security analysis in the context of four typical attacks.
文摘This article outlines the benefits and risks of the distributed ledger technology(DLT)for the clearing and settlement of exchange-traded and OTC securities,followed by a description of the technology’s potential role for central counterparties and central securities depositories.Although the industry and scholars are attempting to solve the technological and operational issues that DLT systems still face,outstanding legal risks are such that the financial industry is asking for more regulatory guidance and intervention.This article wants to contribute to the public policy debate by presenting potential regulatory barriers that may have to be removed for DLT to be fully adopted.In addition,it identifies areas requiring an update of the legal framework in order to address certain prudential and conduct risks that this technology could introduce.
基金supported by the Key R&D Program of Zhejiang Province(2021C01105)the Key R&D Program of Guangdong Province(2020B0101090003)+1 种基金the National Key R&D Program of China(2021YFB2701100)These supports are gratefully acknowledged.
文摘As one of the most concerned digital technologies in recent years,blockchain and distributed ledger technology are an important driving force for a new round of technological development.It is currently in the process of accelerating its evolution and maturity,and has gradually integrated with other digital technologies.It has been applied in many industries,providing decentralized solutions for various industries,realizing innovative storage models,and building a new trust system.As blockchain technology is officially incorporated into China’s new information infrastructure category,the application fields of blockchain have expanded rapidly,gradually extending from the financial field and government affairs to other fields in the real economy.At the same time,with the continuous development of the globalized economy,blockchain technology will also have a profound impact on international technological and economic development.Therefore,for the healthy and orderly development and real implementation of the blockchain industry,standardize the application of blockchain,effectively break through the cognitive and technical barriers between different countries,industries and systems on a global scale,prevent application risks,the development of the global blockchain industry needs standardization basis,which is particularly important and urgent.A sound standard system is an important key to the successful development of technology,and formulating the right standard at the right time for technology development helps ensure the ease of use and interoperability of the technology.From the perspective of international standardization,this article first introduces the general situation of ISO,ITU-T,IEEE,W3C and other international standardization organizations,and sorts out the status quo of the blockchain standardization working groups of mainstream international standardization organizations.All blockchain-related standards under development have been analyzed for the characteristics of international blockchain technology standards and industry application standards.Through data analysis,the overlaps,differences and conflicts in the field of international blockchain standard formulation are sorted out,and suggestions for blockchain standardization work in the application and development of blockchain technology standardization by international organizations and industries are put forward.The plans and layouts of future international standards are summarized to help the development of the international standardization of blockchain.
基金We received funding solely from our institution to perform this research.
文摘A zero-knowledge proof or protocol is a cryptographic technique for verifying private data without revealing it in its clear form.In this paper,we evaluate the potential for zero-knowledge distributed ledger technology to alleviate asymmetry of information in the asset-backed securitization market.To frame this inquiry,we conducted market data analyses,a review of prior literature,stakeholder interviews with investors,originators and security issuers and collaboration with blockchain engineers and researchers.We introduce a new system which could enable all market participants in the securitization lifecycle(e.g.investors,rating agencies,regulators and security issuers)to interact on a unique decentralized platform while maintaining the privacy of loan-level data,therefore providing the industry with timely analytics and performance data.Our platform is powered by zkLedger(Narula et al.2018),a zero-knowledge protocol developed by the MIT Media Lab and the first system that enables participants of a distributed ledger to run publicly verifiable analytics on masked data.
文摘Election allows the voter of a country to select the most suitable group of candidates to run the government.Election in Pakistan is simply paper-based method but some certain political and socio-economic issues turn that simple process in complicated and disputes once.Solutions of such problems are consisting of many methods including the e-voting system.The e-voting system facilitates the voters to cast their votes by electronic means with very easy and convenient way.This also allows maintaining the security and secrecy of the voter along with election process.Electronic voting reduces the human-involvement throughout the process from start to the end.Such system is not established yet in Pakistan.Hence,every election is disputed always.In this paper we proposed the framework of an e-voting system and simulation with the use of blockchain ledger technology.The proposed framework owns the capacity to deal with ballots in Pakistan.The novelty of the framework is that the e-voting system is linked to National Database and Registration Authority(NADRA)database which assures voter’s validation.The fundamental requirements were kept in consideration during the performance evaluation of the system.The results are processed and depicted specially with reference to the number of voters and voting stations,real time of vote casting,network bandwidth and controlling principles.The results support the decision makers and guide them in the foundation and customization of an e-voting system in Pakistan.
文摘Privacy-preservation and effective auditing are two desirable but challenging requirements on distributed ledgers. To meet the requirements, this paper presents an auditing scheme, called as AudiTEE, which can audit a distributed ledger in a generic, efficient, and privacy-preserving manner. AudiTEE leverages Trusted Execution Environment (TEE) to generate confidential but auditable transactions and realize arbitrary, efficient and confidential audit on them. Unfortunately, TEE suffers from some inherent barriers and is itself not a complete solution for fast audit. To tackle these challenges, AudiTEE takes advantage of KAMT (K-anonymity Authentication Based on Merkle Tree) protocol for efficient management on account and user-defined anonymous transactions. Further, to achieve a complete and fast audit with <i>unlinkability</i>, TEE doesn’t process through all but only a comparatively small part of transactions according to a special <i>ktag</i> attached on each transaction to ensure that a user cannot hide transactions from auditor even when auditor is blind with who is involved in each transaction on the ledger. Apart from the above, AudiTEE allows flexible control on user behaviors. We implement a concrete instance of AudiTEE under a bank setting and demonstrate the scalability with all its core functionalities.
基金supported by the National Natural Science Foundation of China(Grant No.62071151)。
文摘Due to the advantages of high volume of transactions and low resource consumption,Directed Acyclic Graph(DAG)-based Distributed Ledger Technology(DLT)has been considered a possible next-generation alternative to blockchain.However,the security of the DAG-based system has yet to be comprehensively understood.Aiming at verifying and evaluating the security of DAG-based DLT,we develop a Multi-Agent based IOTA Simulation platform called MAIOTASim.In MAIOTASim,we model honest and malicious nodes and simulate the configurable network environment,including network topology and delay.The double-spending attack is a particular security issue related to DLT.We perform the security verification of the consensus algorithms under multiple double-spending attack strategies.Our simulations show that the consensus algorithms can resist the parasite chain attack and partially resist the splitting attack,but they are ineffective under the large weight attack.We take the cumulative weight difference of transactions as the evaluation criterion and analyze the effect of different consensus algorithms with parameters under each attack strategy.Besides,MAIOTASim enables users to perform largescale simulations with multiple nodes and tens of thousands of transactions more efficiently than state-of-the-art ones.
文摘In recent years,blockchain technologies have expanded from the finance field to other areas that rely on trustbased solutions.The healthcare industry represents one such area,as digital transformation disrupts relationships between patients,healthcare professionals,and healthcare institutes.Patients and healthcare institutes lack a proficient tool to verify the credentials of medical professionals in a digital environment.Furthermore,healthcare professionals lack a tool where they are in control over their credentials.The first contribution of this paper is a proposal of a solution that leverages the private permissioned Hyperledger Fabric blockchain and smart contracts to provide a source of transparent trust for relationships within the healthcare industry.Second,we pave the ground for GDPR compliance by storing only the hash values on the blockchain.Third,we solve the problem of patient authentication by utilizing cryptographic techniques.Finally,we prove the usability of the proposed solution by implementing a user interface and creating a live deployment.
文摘A key component of blockchain technology is the ledger,viz.,a database that,unlike standard databases,keeps in memory the complete history of past transactions as in a notarial archive for the benefit of any future test.In second-generation blockchains such as Ethereum,the ledger is coupled with smart contracts,which enable the automation of transactions associated with agreements between the parties of a financial or commercial nature.The coupling of smart contracts and ledgers provides the technological background for very innovative application areas,such as Decentralized Autonomous Organizations(DAOs),Initial Coin Offerings(ICOs),and Decentralized Finance(DeFi),which propelled blockchains beyond cryptocurrencies that were the only focus of first generation blockchains,such as Bitcoin.However,the currently used implementation of smart contracts as arbitrary programming constructs has made them susceptible to dangerous bugs that can be exploited maliciously and has moved their semantics away from that of legal contracts.We propose here to recompose the split and recover the reliability of databases by formalizing a notion of contract modeled as a finite-state automaton with well-defined computational characteristics derived from encoding in terms of allocations of resources to actors,as an alternative to the approach based on programming.To complete the work,we use temporal logic as the basis for an abstract query language that is effectively suited to the historical nature of the information kept in the ledger.
