As one of the major threats to the current DeFi(Decentralized Finance)ecosystem,reentrant attack induces data inconsistency of the victim smart contract,enabling attackers to steal on-chain assets from DeFi projects,w...As one of the major threats to the current DeFi(Decentralized Finance)ecosystem,reentrant attack induces data inconsistency of the victim smart contract,enabling attackers to steal on-chain assets from DeFi projects,which could terribly do harm to the confidence of the blockchain investors.However,protecting DeFi projects from the reentrant attack is very difficult,since generating a call loop within the highly automatic DeFi ecosystem could be very practicable.Existing researchers mainly focus on the detection of the reentrant vulnerabilities in the code testing,and no method could promise the non-existent of reentrant vulnerabilities.In this paper,we introduce the database lock mechanism to isolate the correlated smart contract states from other operations in the same contract,so that we can prevent the attackers from abusing the inconsistent smart contract state.Compared to the existing resolutions of front-running,code audit,andmodifier,our method guarantees protection resultswith better flexibility.And we further evaluate our method on a number of de facto reentrant attacks observed from Etherscan.The results prove that our method could efficiently prevent the reentrant attack with less running cost.展开更多
Motivated by the fast evolvement of blockchain technology,cloud-edge platforms,intelligent transportation systems,smart grid,vehicular networks,location based services,and other IoT applications have achieved signific...Motivated by the fast evolvement of blockchain technology,cloud-edge platforms,intelligent transportation systems,smart grid,vehicular networks,location based services,and other IoT applications have achieved significant breakthrough during recent years.Nowadays,blockchain based researches and projects are super-hot topics and focuses for both research and industrial communities.However,most of the current blockchain projects still suffer from insufficient security concerns.The defects of the underlying protocol make the node communication vulnerable to be hijacked,and further exacerbate the fork problem;smart contracts can hardly be fully tested before deployment because of the evolving blockchain platforms,while the smart contracts updating is impossible(or very complicated);current data privacy protection techniques are either inefficient or inaccurate;sharing and cross-chain schemes brought new security problems together with its TPS promotion.The intrinsic security vulnerabilities make the current blockchain based systems and architectures prone to be assaulted,and further do harm to the confidence of the investment on the blockchain industrial.Worse still,blockchain turns out to play a critical role in a lot of existing security solutions,which would be useless if the blockchain is insecure.展开更多
Decentralized finance(DeFi)is a general term for a series of financial products and services.It is based on blockchain technology and has attracted people’s attention because of its open,transparent,and intermediary ...Decentralized finance(DeFi)is a general term for a series of financial products and services.It is based on blockchain technology and has attracted people’s attention because of its open,transparent,and intermediary free.Among them,the DeFi ecosystem based on Ethereum-based blockchains attracts the most attention.However,the current decentralized financial system built on the Ethereum architecture has been exposed to many smart contract vulnerabilities during the last few years.Herein,we believe it is time to improve the understanding of the prevailing Ethereum-based DeFi ecosystem security issues.To that end,we investigate the Ethereum-based DeFi security issues:1)inherited from the real-world financial system,which can be solved by macro-control;2)induced by the problems of blockchain architecture,which require a better blockchain platform;3)caused by DeFi invented applications,which should be focused on during the project development.Based on that,we further discuss the current solutions and potential directions ofDeFi security.According to our research,we could provide a comprehensive vision to the research community for the improvement of Ethereum-basedDeFi ecosystem security.展开更多
In the information age,electronic documents(e-documents)have become a popular alternative to paper documents due to their lower costs,higher dissemination rates,and ease of knowledge sharing.However,digital copyright ...In the information age,electronic documents(e-documents)have become a popular alternative to paper documents due to their lower costs,higher dissemination rates,and ease of knowledge sharing.However,digital copyright infringements occur frequently due to the ease of copying,which not only infringes on the rights of creators but also weakens their creative enthusiasm.Therefore,it is crucial to establish an e-document sharing system that enforces copyright protection.However,the existing centralized system has outstanding vulnerabilities,and the plagiarism detection algorithm used cannot fully detect the context,semantics,style,and other factors of the text.Digital watermark technology is only used as a means of infringement tracing.This paper proposes a decentralized framework for e-document sharing based on decentralized autonomous organization(DAO)and non-fungible token(NFT)in blockchain.The use of blockchain as a distributed credit base resolves the vulnerabilities inherent in traditional centralized systems.The e-document evaluation and plagiarism detection mechanisms based on the DAO model effectively address challenges in comprehensive text information checks,thereby promoting the enhancement of e-document quality.The mechanism for protecting and circulating e-document copyrights using NFT technology ensures effective safeguarding of users’e-document copyrights and facilitates e-document sharing.Moreover,recognizing the security issues within the DAO governance mechanism,we introduce an innovative optimization solution.Through experimentation,we validate the enhanced security of the optimized governance mechanism,reducing manipulation risks by up to 51%.Additionally,by utilizing evolutionary game analysis to deduce the equilibrium strategies of the framework,we discovered that adjusting the reward and penalty parameters of the incentive mechanism motivates creators to generate superior quality and unique e-documents,while evaluators are more likely to engage in assessments.展开更多
As the scale of federated learning expands,solving the Non-IID data problem of federated learning has become a key challenge of interest.Most existing solutions generally aim to solve the overall performance improveme...As the scale of federated learning expands,solving the Non-IID data problem of federated learning has become a key challenge of interest.Most existing solutions generally aim to solve the overall performance improvement of all clients;however,the overall performance improvement often sacrifices the performance of certain clients,such as clients with less data.Ignoring fairness may greatly reduce the willingness of some clients to participate in federated learning.In order to solve the above problem,the authors propose Ada-FFL,an adaptive fairness federated aggregation learning algorithm,which can dynamically adjust the fairness coefficient according to the update of the local models,ensuring the convergence performance of the global model and the fairness between federated learning clients.By integrating coarse-grained and fine-grained equity solutions,the authors evaluate the deviation of local models by considering both global equity and individual equity,then the weight ratio will be dynamically allocated for each client based on the evaluated deviation value,which can ensure that the update differences of local models are fully considered in each round of training.Finally,by combining a regularisation term to limit the local model update to be closer to the global model,the sensitivity of the model to input perturbations can be reduced,and the generalisation ability of the global model can be improved.Through numerous experiments on several federal data sets,the authors show that our method has more advantages in convergence effect and fairness than the existing baselines.展开更多
目的:探讨临床药师在神经内科开展药物治疗管理(medication therapy management,MTM)服务对脑卒中患者二级预防及预后的作用。方法:将2019年5月至2020年9月某三级甲等医院收治的急性缺血性脑卒中与短暂性脑缺血发作患者设为MTM组,采用...目的:探讨临床药师在神经内科开展药物治疗管理(medication therapy management,MTM)服务对脑卒中患者二级预防及预后的作用。方法:将2019年5月至2020年9月某三级甲等医院收治的急性缺血性脑卒中与短暂性脑缺血发作患者设为MTM组,采用前瞻性研究,由临床药师进行MTM服务;将2017年9月至2018年1月收治的急性缺血性脑卒中与短暂性脑缺血发作患者设为对照组,采用回顾性调查研究,仅进行药品使用方法说明服务。记录两组患者出院后3个月的回访情况,对患者的疾病情况、用药情况、二级预防与预后情况进行统计分析。结果:排除失访病例,MTM组最终纳入患者150例,对照组为142例。MTM组发现用药问题269例次,患者接受189例次;发现生活方式问题238例次,患者接受132例次。服务后,MTM组患者符合指南推荐的脑卒中二级预防用药品种数平均为(4.37±2.21)种,对照组患者为(2.88±1.76)种,两组的差异存在统计学意义(P<0.05);在用药监测方面,MTM组患者平均监测药物(1.97±1.41)种,对照组为(1.54±1.06)种,两组的差异存在统计学意义(P<0.05)。MTM组患者中,病情好转140例(占93.33%),复发10例(占6.67%);对照组患者中,病情好转123例(占86.62%),复发19例(占13.38%),两组的差异存在统计学意义(P<0.05)。服务后,两组患者的美国国立卫生研究院卒中量表(national institute of health stroke scale,NIHSS)评分、日常生活能力(activities of daily living,ADL)评分比较,差异均存在统计学意义(P<0.05)。结论:临床药师开展MTM服务能够提高缺血性脑卒中患者二级预防效果,改善患者预后,具有积极意义。展开更多
基金supported byNationalKeyResearch andDevelopment Plan(Grant No.2018YFB1800701)Key-Area Research and Development Program of Guangdong Province 2020B0101090003,CCF-NSFOCUS Kunpeng Scientific Research Fund(CCF-NSFOCUS 2021010)+2 种基金National Natural Science Foundation of China(Grant Nos.61902083,62172115,61976064)Guangdong Higher Education Innovation Group 2020KCXTD007 and Guangzhou Higher Education Innovation Group(No.202032854)Guangzhou Fundamental Research Plan of“Municipalschool”Jointly Funded Projects(No.202102010445).
文摘As one of the major threats to the current DeFi(Decentralized Finance)ecosystem,reentrant attack induces data inconsistency of the victim smart contract,enabling attackers to steal on-chain assets from DeFi projects,which could terribly do harm to the confidence of the blockchain investors.However,protecting DeFi projects from the reentrant attack is very difficult,since generating a call loop within the highly automatic DeFi ecosystem could be very practicable.Existing researchers mainly focus on the detection of the reentrant vulnerabilities in the code testing,and no method could promise the non-existent of reentrant vulnerabilities.In this paper,we introduce the database lock mechanism to isolate the correlated smart contract states from other operations in the same contract,so that we can prevent the attackers from abusing the inconsistent smart contract state.Compared to the existing resolutions of front-running,code audit,andmodifier,our method guarantees protection resultswith better flexibility.And we further evaluate our method on a number of de facto reentrant attacks observed from Etherscan.The results prove that our method could efficiently prevent the reentrant attack with less running cost.
基金supported by Key-Area Research and Develop-ment Program of Guangdong Province 2020B0101090003。
文摘Motivated by the fast evolvement of blockchain technology,cloud-edge platforms,intelligent transportation systems,smart grid,vehicular networks,location based services,and other IoT applications have achieved significant breakthrough during recent years.Nowadays,blockchain based researches and projects are super-hot topics and focuses for both research and industrial communities.However,most of the current blockchain projects still suffer from insufficient security concerns.The defects of the underlying protocol make the node communication vulnerable to be hijacked,and further exacerbate the fork problem;smart contracts can hardly be fully tested before deployment because of the evolving blockchain platforms,while the smart contracts updating is impossible(or very complicated);current data privacy protection techniques are either inefficient or inaccurate;sharing and cross-chain schemes brought new security problems together with its TPS promotion.The intrinsic security vulnerabilities make the current blockchain based systems and architectures prone to be assaulted,and further do harm to the confidence of the investment on the blockchain industrial.Worse still,blockchain turns out to play a critical role in a lot of existing security solutions,which would be useless if the blockchain is insecure.
基金supported by the Key-Area Research and Development Program of Guangdong Province 2020B0101090003CCF-NSFOCUS Kunpeng Scientific Research Fund (CCFNSFOCUS 2021010)+4 种基金Innovation Fund Program of the Engineering Research Center for Integration and Application of Digital Learning Technology of Ministry of Education under Grant No.1221027National Natural Science Foundation of China (Grant Nos.61902083,62172115,61976064)Guangdong Higher Education Innovation Group 2020KCXTD007 and Guangzhou Higher Education Innovation Group (No.202032854)Guangzhou Fundamental Research Plan of“Municipal-School”Jointly Funded Projects (No.202102010445)Guangdong Province Science and Technology Planning Project (No.2020A1414010370).
文摘Decentralized finance(DeFi)is a general term for a series of financial products and services.It is based on blockchain technology and has attracted people’s attention because of its open,transparent,and intermediary free.Among them,the DeFi ecosystem based on Ethereum-based blockchains attracts the most attention.However,the current decentralized financial system built on the Ethereum architecture has been exposed to many smart contract vulnerabilities during the last few years.Herein,we believe it is time to improve the understanding of the prevailing Ethereum-based DeFi ecosystem security issues.To that end,we investigate the Ethereum-based DeFi security issues:1)inherited from the real-world financial system,which can be solved by macro-control;2)induced by the problems of blockchain architecture,which require a better blockchain platform;3)caused by DeFi invented applications,which should be focused on during the project development.Based on that,we further discuss the current solutions and potential directions ofDeFi security.According to our research,we could provide a comprehensive vision to the research community for the improvement of Ethereum-basedDeFi ecosystem security.
基金This work is supported by the National Key Research and Development Program(2022YFB2702300)National Natural Science Foundation of China(Grant No.62172115)+2 种基金Innovation Fund Program of the Engineering Research Center for Integration and Application of Digital Learning Technology of Ministry of Education under Grant Number No.1331005Guangdong Higher Education Innovation Group 2020KCXTD007Guangzhou Fundamental Research Plan of Municipal-School Jointly Funded Projects(No.202102010445).
文摘In the information age,electronic documents(e-documents)have become a popular alternative to paper documents due to their lower costs,higher dissemination rates,and ease of knowledge sharing.However,digital copyright infringements occur frequently due to the ease of copying,which not only infringes on the rights of creators but also weakens their creative enthusiasm.Therefore,it is crucial to establish an e-document sharing system that enforces copyright protection.However,the existing centralized system has outstanding vulnerabilities,and the plagiarism detection algorithm used cannot fully detect the context,semantics,style,and other factors of the text.Digital watermark technology is only used as a means of infringement tracing.This paper proposes a decentralized framework for e-document sharing based on decentralized autonomous organization(DAO)and non-fungible token(NFT)in blockchain.The use of blockchain as a distributed credit base resolves the vulnerabilities inherent in traditional centralized systems.The e-document evaluation and plagiarism detection mechanisms based on the DAO model effectively address challenges in comprehensive text information checks,thereby promoting the enhancement of e-document quality.The mechanism for protecting and circulating e-document copyrights using NFT technology ensures effective safeguarding of users’e-document copyrights and facilitates e-document sharing.Moreover,recognizing the security issues within the DAO governance mechanism,we introduce an innovative optimization solution.Through experimentation,we validate the enhanced security of the optimized governance mechanism,reducing manipulation risks by up to 51%.Additionally,by utilizing evolutionary game analysis to deduce the equilibrium strategies of the framework,we discovered that adjusting the reward and penalty parameters of the incentive mechanism motivates creators to generate superior quality and unique e-documents,while evaluators are more likely to engage in assessments.
基金National Natural Science Foundation of China,Grant/Award Number:62272114Joint Research Fund of Guangzhou and University,Grant/Award Number:202201020380+3 种基金Guangdong Higher Education Innovation Group,Grant/Award Number:2020KCXTD007Pearl River Scholars Funding Program of Guangdong Universities(2019)National Key R&D Program of China,Grant/Award Number:2022ZD0119602Major Key Project of PCL,Grant/Award Number:PCL2022A03。
文摘As the scale of federated learning expands,solving the Non-IID data problem of federated learning has become a key challenge of interest.Most existing solutions generally aim to solve the overall performance improvement of all clients;however,the overall performance improvement often sacrifices the performance of certain clients,such as clients with less data.Ignoring fairness may greatly reduce the willingness of some clients to participate in federated learning.In order to solve the above problem,the authors propose Ada-FFL,an adaptive fairness federated aggregation learning algorithm,which can dynamically adjust the fairness coefficient according to the update of the local models,ensuring the convergence performance of the global model and the fairness between federated learning clients.By integrating coarse-grained and fine-grained equity solutions,the authors evaluate the deviation of local models by considering both global equity and individual equity,then the weight ratio will be dynamically allocated for each client based on the evaluated deviation value,which can ensure that the update differences of local models are fully considered in each round of training.Finally,by combining a regularisation term to limit the local model update to be closer to the global model,the sensitivity of the model to input perturbations can be reduced,and the generalisation ability of the global model can be improved.Through numerous experiments on several federal data sets,the authors show that our method has more advantages in convergence effect and fairness than the existing baselines.
文摘目的:探讨临床药师在神经内科开展药物治疗管理(medication therapy management,MTM)服务对脑卒中患者二级预防及预后的作用。方法:将2019年5月至2020年9月某三级甲等医院收治的急性缺血性脑卒中与短暂性脑缺血发作患者设为MTM组,采用前瞻性研究,由临床药师进行MTM服务;将2017年9月至2018年1月收治的急性缺血性脑卒中与短暂性脑缺血发作患者设为对照组,采用回顾性调查研究,仅进行药品使用方法说明服务。记录两组患者出院后3个月的回访情况,对患者的疾病情况、用药情况、二级预防与预后情况进行统计分析。结果:排除失访病例,MTM组最终纳入患者150例,对照组为142例。MTM组发现用药问题269例次,患者接受189例次;发现生活方式问题238例次,患者接受132例次。服务后,MTM组患者符合指南推荐的脑卒中二级预防用药品种数平均为(4.37±2.21)种,对照组患者为(2.88±1.76)种,两组的差异存在统计学意义(P<0.05);在用药监测方面,MTM组患者平均监测药物(1.97±1.41)种,对照组为(1.54±1.06)种,两组的差异存在统计学意义(P<0.05)。MTM组患者中,病情好转140例(占93.33%),复发10例(占6.67%);对照组患者中,病情好转123例(占86.62%),复发19例(占13.38%),两组的差异存在统计学意义(P<0.05)。服务后,两组患者的美国国立卫生研究院卒中量表(national institute of health stroke scale,NIHSS)评分、日常生活能力(activities of daily living,ADL)评分比较,差异均存在统计学意义(P<0.05)。结论:临床药师开展MTM服务能够提高缺血性脑卒中患者二级预防效果,改善患者预后,具有积极意义。
