Blockchain, as an emerging technology, provides a brand-new idea for the improvement of personalized recommender systems with its characteristics of decentralization, tamper-proof, anonymity and traceability.Therefore, the main problems faced by the recommender systems in recent years and the opportunities brought by blockchain technology were summarized firstly.Then, literature analysis was adopted to analyze and summarize the research on the application of blockchain technology in recommender systems from four aspects: time distribution, literature types, research questions and evaluation indicators.The results show that the blockchain is of great significance for solving the problems of data security and privacy protection, data sharing, data trustworthiness and recommendation transparency of recommender systems.Existing studies mainly focus on solving the problem of data security and privacy protection in recommender systems, while further breakthroughs are needed in cross-platform data sharing, design of incentive mechanisms and system scalability.
Satellite internet have the advantages of wide coverage, low latency, large transmission capacity and no geographical infl uence.It can provide ubiquitous internet access services for users all over the world.However, the heterogeneity of satellite internet and ground network, the channel opening and node exposure of satellite internet will pose a security threat to network access and resource management.Aiming at the security problem of satellite internet, a multilayer satellite internet security management architecture based on blockchain was proposed.As a distributed ledger technology, blockchain uses chain data structure to verify and store data, and adopts encryption methods to maintain that data blocks cannot be tampered.Blockchain can realize network security access, trusted resource management, and provide information security protection for satellite internet.This paper improved the security of satellite internet by integrating blockchain technology with satellite internet.
Aiming at the problems of low accuracy of current detection methods and poor generalization of model, a honeypot contract detection method based on KOLSTM deep learning model was proposed.Firstly, by analyzing the characteristics of honeypot contract, the concept of key opcode was proposed, and a keyword extraction method which could be used to select the key opcode in smart contract was designed.Secondly, by adding the key opcode weight mechanism to the traditional LSTM model, a KOLSTM model which could simultaneously capture the sequence features and key opcode features hidden in the honeypot contract was constructed.Finally, the experimental results show that the model had a high recognition accuracy.Compared with the existing methods, the F-score is improved by 2.39% and 19.54% respectively in the two classification and multi-classification detection scenes.
Blockchain technology has the features of decentralization, high credibility, non-tampering and traceability, which can address the trust problem in traditional access control technology.Based on the implementation with blockchain, the unique advantages of applying blockchain to access control are analyzed from two aspects: based on transaction and based on smart contract.Based on the key issues in blockchain application, the current research progress is summarized from three key technologies: dynamic access control, blockchain space optimization, and privacy data protection.Based on the challenges faced by the current blockchain-based access control mechanism, five research prospects are proposed.
Most of the blockchain-based identity authentication systems are based on public blockchain, which are still essentially traditional centralized identity management and verification methods, making it difficult to meet the needs of trusted access and fine-grained access control in microgrids.Therefore, based on the FISCO BCOS consortium blockchain technology, a distributed identity authentication system supporting multi-center was designed.A DID-based identity management protocol to achieve autonomous control of user identity in a practical scenarios was designed.Distributed trusted access technology for end nodes in microgrids was studied, and privacy-protecting credentials based on zero-knowledge proof were designed.This scheme meets the requirements of trustworthy and verifiable user identity in different privacy security scenarios, and achieves autonomous control of entity identity, fine-grained access control and trusted data exchange.The usability and effectiveness of the proposed algorithm are demonstrated through system experiments and performance analysis.
Federated learning is a new distributed machine learning technology, where training tasks are deployed on user side and training model parameters are sent to the server side.In the whole process, participants do not need to share their own data directly, which greatly avoids privacy issues.However, the trust relationship between mobile users in the learning model has not been established in advance, there is hidden safety when users perform cooperative train with each other.In view of the above problems, a federated learning scheme for mobile network based on reputation evaluation mechanism and blockchain was proposed.The scheme allowed the server side to use subjective logic models to evaluate the reputation of participating mobile users and provided them with credible reputation opinions sharing environment and dynamic access strategy interface based on the technique of smart contract of blockchain.Theoretical and experimental analys is results show that the scheme can enable the server side to select reliable users for training.And it can achieve more fair and effective reputation calculations, which improves the accuracy of federated learning.
A blockchain-based data integrity multi-party high-efficiency audit mechanism (MBE-ADI) for the big data environment was proposed.A hybrid Merkle DAG structure based on data domain was built to organize data, and realized the simultaneous verification of a large number of unstructured data in the big data environment.In order to deal with the problem of large amount of data in the big data environment, a multi copy deterministic verification method based on BLS signature was designed to realize the efficient verification of data integrity supporting multiple copies.A dual verification audit architecture based on consortium blockchain was designed to realize decentralized automatic audit and audit history credible traceability.At the same time, data integrity verification services were provided for data owners and data users to realize reliable acquisition of data.The test proves the feasibility of the system and the efficiency of data integrity audit.
In response to the problem that in the industrial Internet of things （IIoT）， industrial equipment stored data in the cloud， causing data to be easily tampered with and unable to track malicious users， causing a vicious circle， with the help of the traceability and immutability of the blockchain， a dual verifiable cloud storage scheme based on the blockchain was proposed.Firstly， homomorphic encryption technology was used to encrypt data and upload it to the cloud ， which ensured transmission security and realized data privacy protection.Secondly， the aggregated ciphertext and uploader information were stored on the blockchain， which could effectively avoid the risk of data being tampered with by illegal users， and could trace malicious users to achieve double verification of cloud data integrity.Finally， a safety analysis was carried out to prove that the proposed scheme is safer and more reliable than similar schemes.
To solve the problems of privacy and security in the electronic evidence sharing of Internet of vehicles， a sharing scheme of electronic evidence in the Internet of vehicles based on signcryption and blockchain was proposed.The evidence ciphertext and the evidence report were stored in the cloud server and the block chain respectively to realize the secure storage and sharing of the electronic evidence.The identity-based signcryption technology was used to ensure the confidentiality of data， and the proxy re-encryption technology was used to realize the sharing of electronic evidence of Internet of vehicles by insurance companies.The aggregation signature technique was introduced to reduce the computation cost of multi vehicle user signature verification.The reliability of electronic evidence was improved by using credibility incentive mechanism.Security analysis shows that the proposed scheme achieves data confidentiality， integrity， verifiability and unforgeability.Compared with the existing schemes， the proposed scheme has certain advantages in terms of computational overhead.
Aiming at the needs of edge computing for data privacy, the correctness of calculation results and the auditability of data processing, a privacy protection method for edge computing based on blockchain and federated learning was proposed, which can realize collaborative training with multiple devices at the edge of the network without a trusted environment and special hardware facilities.The blockchain was used to endow the edge computing with features such as tamper-proof and resistance to single-point-of-failure attacks, and the gradient verification and incentive mechanism were incorporated into the consensus protocol to encourage more local devices to honestly contribute computing power and data to the federated learning.For the potential privacy leakage problems caused by sharing model parameters, an adaptive differential privacy mechanism was designed to protect parameter privacy while reducing the impact of noise on the model accuracy, and moments accountant was used to accurately track the privacy loss during the training process.Experimental results show that the proposed method can resist 30% of poisoning attacks, and can achieve privacy protection with high model accuracy, and is suitable for edge computing scenarios that require high level of security and accuracy.
Multi-access edge computing (MEC) can provide high-quality service capabilities for computing-intensive services and delay-sensitive services in urban rail traffic.However, many edge facilities in rail traffic edge computing network are exposed to an open environment, and their privacy protection and transmission security are facing great challenges.Blockchain has functional characteristics such as distributed ledger, consensus mechanism, smart contract, and decentralized application.Therefore, the use of blockchain can build a systematic security protection mechanism for the distributed rail traffic edge computing network to ensure network security and data security and realize high-quality urban rail traffic services.Firstly, the basic concept of the blockchain and the urban rail traffic edge computing network architecture were introduced.Then, the structure and application content of the rail traffic edge computing network security protection mechanism integrated with the blockchain was discussed in detail.Finally, the open research issues and challenges of the security protection mechanism were analyzed.
In order to meet the needs of data security sharing in multi-user environment, a public key searchable encryption scheme supporting one-to-many mode was proposed.Specifically, the data owner could specify multiple users to retrieve the ciphertext by executing the encryption algorithm once, so as to achieve more flexible sharing of ciphertext data.In addition, the specific file encryption key transfer algorithm was designed to ensure that the user could decrypt and obtain the plaintext correctly after retrieving the ciphertext.Combined with the blockchain technology, the smart contract execution detection algorithm was used to ensure the correctness of the retrieval results.In terms of security, based on the decisional bilinear Diffie-Hellman hypothesis and the modified bilinear Diffie-Hellman hypothesis, it was proved that the proposed scheme satisfies the security requirements of keyword indistinguishability and trapdoor information indistinguishability under the random oracle model, and could resist the internal keyword guessing attack.Finally, the proposed scheme and the existing related schemes were simulated by using jPBC cryptolibrary, and the test results show that the proposed scheme has high computational efficiency.
For scenarios such as space-integrated-ground information network where satellite resources are limited and communication delays are large, in response to the requirements of non-interactive key exchange in the satellite communication network, a non-interactive key exchange scheme for space-integrated-ground information network based on blockchain and Diffi e-Hellman key exchange protocol was proposed.The scheme arranged the blockchain in space-integrated-ground information network to form TDYTH blockchain.After the satellite node was registered, its related information was stored in TDYTH blockchain.When the satellite node needed to communicated with the long-distance node such as NCC, the two parties could query the immutable information stored in TDYTH blockchain to generated the shared session key, established consensus, and then completed access authentication and key distribution under non-interactive conditions.The result of simulation demonstrated that the scheme we proposed could meet the requirements of non-interactive key distribution of satellites and other nodes, and could signifi cantly improved security and robustness.
Aiming at the problems of high process instantiation cost and difficult version iteration in the current blockchain-based business process management systems, a choreography-driven blockchain business process management framework was proposed.The framework included a general smart contract that could be used to store business process choreography meta-models, model component evolution versions, and instance execution status.The cost of process model instantiation on the blockchain was significantly reduced by delaying model elements instantiation timing and integrating multiple process instances.At the same time, a version control method based on model data reuse and voting mechanism was introduced, so that process instances of different versions of orchestration models could be created in a single smart contract.A real case validates the effectiveness of the framework in distributed business process management.
In order to solve the problems that the monitoring data was easy to be tampered with in the process of railway engineering construction safety monitoring, and the authenticity of the data might be questioned during the accountability of accidents, a blockchain-based railway engineering construction safety monitoring data sharing model was proposed.The characteristics of automatic execution of smart contracts ensured the transparency of the process of monitoring data on the chain.In the PBFT algorithm, there was a problem that the Byzantine nodes and the normal nodes were selected as the master node with the same probability, a reputation-based practical Byzantine fault tolerance algorithm was proposed.Streaming data on the chain might cause network congestion, which simplified the consensus protocol and reduced the time complexity from O(n2) to O(n).A comparative experiment was conducted using Hyperledger Caliper to prove that the delay of the improved algorithm is lower than PBFT algorithm, and the throughput is higher than PBFT algorithm.A quantitative analysis of the possibility of attack and the probability of successful attack was carried out, and it was determined that the smart contract provides tamper-proof modification for the monitoring data on the chain.Comparative analysis proves that the proposed blockchain-based railway engineering construction safety monitoring data sharing model is good than other models in terms of consensus efficiency, TPS and block generation speed.
Data is the foundation of the digital economy.However, the issue of data confirmation is currently controversial.As a new type of asset, capitalization standards and pricing standards are still in the exploration stage, and the construction of big data trading platforms is in the ascendant.The status quo and main problems of data right confirmation, pricing and trading were reviewed, and from this condenses, a new big data trading model was proposed, which is the iterative relationship between data right confirmation, pricing and trading.Finally, combined with the technical characteristics of the blockchain, a scheme of big data transaction platform based on the consortium blockchain was put forward, which is from the perspective of individuals and data transaction parties.The platform’s rights and interests protection, pricing mechanism and transaction mode have been designed.
The blockchain technology can ensure the high security, high privacy and traceability of data asset management.Through research on the current blockchain-based data asset management mechanism, it is concluded that the current management mechanism is only applied in a certain layer of the blockchain framework.In order to solve this problem, a new mechanism of data asset management based on blockchain was proposed.The mechanism combined and applied all layers in the blockchain framework.In addition, this mechanism added a node authority control mechanism at the network layer, realized the consensus mechanism with customizable attributes at the consensus layer, optimized the structure and built indexes to speed up data query efficiency at the data layer, realized intelligent data management and sharing at the smart contract layer, and realized information encryption with customizable encryption algorithms at the transaction layer.Experimental results show that the new mechanism of data asset management based on blockchain improves the efficiency of data query on chain by 2.33 times compared with the traditional mechanism.
Due to the lack of communication mechanism between inter-blockchain services, it is difficult to formulate effective interconnection between different blockchain.Under the smart services ecosystem, two parties of the transaction not only execute the single transaction of data assets, but also extend the scope of their services to cover a wider range of digital assets transfer scenarios.An inter-blockchain communication(IBC) framework for smart service transaction is designed.With component-based and modular design, it makes flexible for the subject and object application of smart service transaction to access IBC framework and thus promote inter-blockchain scalability.Finally, a three-phrase inter-blockchain communication protocol for smart service transaction is proposed to ensure the atomicity and consistency of inter-blockchain ecosystem.
With the continuous development of blockchain technology, different chains are derived due to different adaptation scenarios.Each chain has its own characteristics, such as public chains like bitcoin and ethereum, a large number of private chains and alliance chains.But as far as the current Internet is concerned, the implementation of many application scenarios on traditional blockchains has become particularly inconvenient.A master-slave blockchain (MSBC) architecture was proposed, which was mainly composed of a master block, a subordinate master block and a subordinate micro block.The master chain was composed of master blocks.Each master block has a slave master block and multiple slave micro block on its side chain.In addition, the master block and the master block were directly connected by the Hash of the previous block, the master block and the slave master block were connected by the Hash of the unique information, and the slave micro block and the previous block (whatever the slave master block or the slave micro block) was also connected by the Hash of the previous block.In talent chain, this kind of structure could put a person’s fixed resume information on the master chain, but updated resume information constantly on the slave side chain.MSBC architecture was more scalable, and it could improve the efficiency of data query.The experimental results show that the framework in the similar applications such as talent chain is feasible and the query efficiency has been improved greatly.
In order to solve the problems of the low transaction success rate and network imbalance of the payment channel network, an efficient routing strategy of blockchain-based payment channel network was proposed.This strategy established a dedicated payment channel for the high-priority services according to the service type and service priority, and divided the conventional business into multiple transaction unit.Furthermore, a channel balanced routing algorithm was designed to route each transaction unit, which could reduce the number of transactions on the blockchain and maintain long-term stable operation of the off-chain payment channel, as well as improve the transaction success rate.In addition, in order to avoid the temporary shortage of funds and unavailability of channels due to a certain link occupied by multiple transactions simultaneously, a transaction queuing mechanism in the payment channel network was designed.This mechanism established the forwarding rules for transactions by calculating the escrow amount between the node that transactions arrived and the next hop node, where the channel balanced routing algorithm was used to calculate the new forwarding path for the nodes that could not carry out capital injection within the queuing threshold.The simulation results show that the proposed strategy could improve the transaction success rate and realize the equilibrium of the payment channel network.
Non-fungible token (NFT) based on blockchain is a kind of digital asset ownership recorded on blockchain, which is unique, irreplaceable and indivisible.It has been widely used in collectibles, encrypted artworks and games.Firstly, the concepts, characteristics and development processes of NFT were mainly introduced, and its core elements and typical application fields were analyzes.The problems and risks faced by NFT in the aspects of property right, value, technology and supervision were also pointed out.After that, the related literatures on NFT were reviewed, and the research issues of NFT in value evaluation, transaction mode and pricing were proposed.Finally, the trend of NFT driven digital capitalization was prospected.
Aiming at the problem that the performance of intelligent detection models was limited by the representation ability of original data (features), a residual network structure ResNet-32 was designed to automatically mine the intricate association relationship between original features, so as to actively learn the high-level abstract features with rich semantic information.Low-level features were more transaction content descriptive, although their distinguishing ability was weaker than that of the high-level features.How to integrate them together to obtain complementary advantages was the key to improve the detection performance.Therefore, multi feature fusion methods were proposed to bridge the gap between the two kinds of features.Moreover, these fusion methods can automatically remove the noise and redundant information from the integrated features and further absorb the cross information, to acquire the most distinctive features.Finally, block-chain abnormal transaction detection model (BATDet) was proposed based on the above presented methods, and its effectiveness in the abnormal transaction detection is verified.
Aiming at the key management of electronic health records (EHR) in a distributed system and user identity tracing issues, a distributed EHR fine-grained traceability scheme based on blockchain was proposed.Combining chameleon hash and zero-knowledge proof technology, the registration of nodes on the blockchain and the generation of identity certificates were realized, and the traceability of malicious users on the blockchain was realized.Besides, given the single point of failure problem of key management, the attribute-based encryption scheme of distributed ciphertext strategy was designed to achieve secure and fine-grained data access control, and multiple decryption agency blockchain nodes were set up to jointly distribute the attribute private keys of user nodes.The security analysis shows that the traceable distributed key generation attribute-based encryption algorithm based on the blockchain is adaptively secure under the random oracle model, and through experiments, the feasibility and practicability of the proposed scheme are shown.
Abtract: The development of raw milk is an important direction for the development of China’s dairy industry, and a traceability system for the raw milk industry was proposed for the development of the entire industry crucially.The characteristics of the raw milk industry were analyzed and four major problems were proposed as the timeliness, the problems found after the fact, the difficulty in tracing the victims, the quality control system, such as difficulties in gaining trust, which were the main characteristics that distinguish the raw milk industry from other agricultural industries, and leaded to traceability in traditional agriculture.The mechanism or even the popular blockchain-based traceability mechanism for agricultural products could not meet the traceability requirements of the raw milk industry.Based on this finding, RMChain, a traceability system for raw milk supply chain system scheme, was designed to meet the requirements of the existing blockchain-based traceability mechanisms in the raw milk industry.In addition to the various advantages of the chain traceability mechanism, it was also optimized specifically for the characteristics of raw milk, which made it easy for users to trace the product and facilitate the traceability of the milk.The tracking and location of problem milk and consumer compensation effectively improved the traceability status of the fresh milk industry.For the problem of large files seriously affecting the performance of the blockchain, a multi-party storage model based on the importance of data was also designed.The feasibility of RMChain was verified.
The previous assured deletion schemes ignored that the privacy is threated by the relevance between data and user identity, exposing user behavior to the cloud service provider or attackers.Aiming at the above problems, an assured deletion approach based on blockchain was proposed.The improved linkable ring signature scheme was adopted to make user achieve anonymous assured deletion by setting specific link symbol in the signature.Moreover, the blockchain technology was leveraged to guarantee the nonrepudiation of assured deletion.Theoretical analysis and experimental results show that the proposed approach can meet the assured deletion requirements of user data in cloud storage, and its anonymity can effectively prevent attackers from tracking and analyzing user behavior.
Internet of things (IoT) is changing the data-driven smart industry due the massive availability of IoT data.Nevertheless, the IoT also poses some challenging issues like decentralization, poor interoperability, privacy and security vulnerabilities.The recent advent of blockchain can potentially tackle the above issues.The marriage of blockchain and IoT was investigated, and named this integration as blockchain of things (BCoT).In particular, the IoT and blockchain technology was introduced firstly.The convergence of blockchain and IoT was introduced, and the proposal of BCoT architecture was presented.The application of the Internet of things in the industry was further discussed.Finally, the open research directions in the field were outlined.
The blockchain provides an immutable, transparent, and decentralized method for data storage.However, as the volume of data gradually increases, the public blockchain system requires significant storage space.The bitcoin block's structure was analyzed.A method was introduced to compress the size of transactions in the bitcoin blockchain by encoding specific fields.Experiment shows that the proposed method can reduce the storage space of the bitcoin blockchain by 18.13%.
To meet efficient, safe, covert and stable transmission of confidential information, the transaction data structures, location and capacity of potential convert channels were analyzed.Then a formal security model of covert transmission in the bitcoin blockchain environment was proposed, which would not break the transaction structures, add special transaction content, can overcome shortcomings of traditional convert channels and protect the anonymity of both sender and receiver.The proposed security model opens a promising avenue of covert transmission, which is of great significance to promote the secure transmission technologies for the national special applications.
A blockchain technology based on practical Byzantine fault tolerance (PBFT)algorithm was proposed.First of all, the traditional practical Byzantine fault tolerant algorithm was explained.The traditional algorithm included six phases: pre-stage, demand, pre-preparation, preparation, confirmation, and response.However, traditional algorithms had the disadvantages of poor real-time performance, lack of penalty mechanisms, and high bandwidth.In response to these problems, the traditional algorithm was improved, which specifically involved the accounting node, the consensus process, and the view switching process.The feasibility of the improved algorithm was further proved by testing.Applying this algorithm to power grid enterprises, the federal reserve system was implemented by the constructedvirtual warehouse, which also reduced the consumption of inventory funds.And the efficiency of inventory management in power grid enterprises was improved.
In order to solve the problem that the existing publishing systems were vulnerable to tampering, and it was difficult to recommend service information to “cold start” users, a blockchain-based service publishing scheme that supported cold-start user recommendations was proposed.The latent feature mapping model of a single auxiliary domain was extended to two auxiliary domains to make more accurate recommendations for cold start users in the target domain.In addition, the microservice architecture and block technology were combined to ensure system scalability, reliability and security.The experimental results of three real data sets extracted from Amazon transaction data show that the proposed recommendation model is better than most other recommendation methods, and the service release information can be safely stored in the blockchain to ensure that it is not changed.
While the security of blockchain has been the central concern of both academia and industry since the very start, new security threats continue to emerge, which poses great risks to the blockchain ecosystem.A systematic study was conducted on the most state-of-the-art research on potential security issues of blockchain.Specifically, a taxonomy was developed by considering the blockchain framework as a four-layer system, and the analysis on the most recent attacks against security loopholes in each layer was provided.Countermeasures that can strengthen the blockchain were also discussed by highlighting their fundamental ideas and comparing different solutions.Finally, the forefront of research and potential directions of blockchain security were put forward to encourage further studies on the security of blockchain.
Compared with the traditional internet,the SDN-based internet of things (IoT) has a wider coverage,more connected devices,more complex data transmission.There are many security technical challenges.The security challenges of SDN-based IoT deployment were firstly analyzed,and then the advantages of blockchain technology in solving those security issues were introduced.Finally,to add a blockchain-based security layer was proposed,which acted as a security gateway,data entering the IoT was verified accurately one time.Each security gateway was added to the blockchain system as an equal blockchain node,combined with the traceability and non-tampering of the blockchain system,the security performance and efficiency of SDN-based IoT deployments was improved.
In order to deploy a blockchain on the non-continuous connectivity delay tolerant network,a blockchain trading mechanism was designed,which could run on this type of network.First,the identifier was introduced into the existing block structure and a block structure on the attached chain was presented,which could append the blocks generated during network disconnection.Then,the approaches including the block package,block mining and block consensus on the attached chain were proposed.Finally,a confirming consensus approach was presented to avoid block fraud in the process of appending the attached chain.Through theoretical proof and experimental analysis,the proposed mechanism can support blockchain trading in the delay tolerant network.
In view of the abuse of power by managers in the traditional centralized trading system, a security model without managers for the blockchain-based trading system was proposed, which also solved the problems of unsafe endorsement, untimely trading, low auditing efficiency and dynamic inefficiency caused by the elimination of managers.The proposed security model realized decentralization based on the blockchain technology, by using homomorphic authentication-based public auditing to achieve the secure endorsement and key updating for non-manager groups and efficient verification for transaction information respectively, introducing the reputation-based incentive mechanism to ensure the timeliness of the transaction.Finally, the security and reliability of the proposed security model were demonstrated by security proof and performance analysis, and the communication and computing costs are both lower than IPANM.
To improve the transparency and traceability of access control, a blockchain-based access control mechanism for data traceability and provenance was proposed.The proposed access control policy was transferred to the smart contract and deployed on the blockchain, and the access authorization evaluation was realized by executing the smart contract deployed on the blockchain to ensure the decentralization, transparency and traceability of the access control process.The manner of combining off-chain and on-chain was adopted, the object was stored in off-chain data server, and the object index was generated by the object storage address and hash value, and deployed on the object blockchain.The log of object access authorization and access were recorded in the log blockchain, any misbehavior was immutably recorded.The security analysis show that, the proposed mechanism achieve the properties of decentralization, transparency and traceability while ensuring the privacy of data.
In blockchain-enabled mobile edge computing (BMEC) systems,a new class of blockchain application related computation tasks was introduced to the system.Due to the differences of parallelism among computation tasks,heterogenous computing framework was introduced to suitably split various computation tasks on processors with vastly different processing power to achieve efficient task execution.Under the limited computation and communication resources,a system-wide utility maximization problem by jointly considering heterogeneous processor scheduling,computation and bandwidth resource allocation was formulated as a mixed-integer nonlinear programming problem.To solve the problem efficiently,the formulated problem was transformed into two sub-problems,namely application-driven heterogeneous processor scheduling and joint resource allocation,and a Lagrange-dual based algorithm was proposed.Simulation results show that the proposed scheme can effectively improve the system-wide utility of the BMEC system.
Considering the heterogeneity of various IoT system and the single point failure of centralized data-processing platform,a decentralized IoT data sharing and storage method based on blockchain technology was proposed.The block consensus and decentralized storage of shared data were realized through the PoS consensus mechanism.A block layered propagation mechanism between consensus node and verified node was proposed based on the Gossip protocol.The block propagation delay model and decentralization evaluation model of blockchain networks were derived.The trade-off between the block propagation delay and the decentralization degree of networks was analyzed.The simulation results demonstrate that the block propagation delay and degree of network decentralization decrease with the increase of minimal capabilities of consensus nodes.As an application example,in the trajectory data sharing scenario of confirmed patients,the data sharing smart contract is implemented and tested based on the Ethereum development platform.
Blockchain′s characteristics of non-temper and decentralization can be utilized to improve the data security and scalability of storage systems,called blockchain storage.These works that combine storage with blockchain technology,are mainly divided into three categories:decentralized storage systems based on blockchain,improve the performance of existing storage systems based on blockchain,and the underlying storage strategies of blockchain.These works were summarized,the current blockchain storage systems were compared,the main challenges that blockchain and storage being facing were discussed and its future development was forecasted.
A new blockchain chain protocol was proposed,which allowed adjusting the loading time of the mining process.This strategy reduced the ASIC and CPU mining rate of the gap,so that the using of ASIC mining is limited.Finally,the safety of this new chain structure was analyzed and compared to the original chain protocol.
With the development of intelligent transportation system,the vehicles will no longer be controlled by the traditional traffic light when they enter or leave the intersection.Instead,they will interact with the local server (LS) near the intersection and accept the regulation of LS.The basic of the security vehicle communication at intersections is authentication of network node.Based on this,an anonymous vehicle authentication scheme based on blockchain technology was proposed.The scheme employed a hybrid cryptography based on identity and hash message authentication code,and recorded the authentication results in blockchains.According to simulation testing and result analysis,the scheme ensures the anonymity and privacy-preserving,with less communication overhead compared to other methods.
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