New public blockchain protocol based on sharding and aggregate signatures

2021 ◽  
Vol 27 (1) ◽  
pp. 83-99
Author(s):  
Jinhua Fu ◽  
Wenhui Zhou ◽  
Mixue Xu ◽  
Xueming Si ◽  
Chao Yuan ◽  
...  
Keyword(s):  
Mobile Computing ◽  
Random Function ◽  
Security Analysis ◽  
Experimental Results ◽  
Processing Capacity ◽  
Blockchain Technology ◽  
New Public ◽  
Potential Applicability ◽  
Speed Up ◽  
Aggregate Signatures

Existing blockchains, especially public blockchains, face the challenges of scalability which means the processing capacity will not get better with the addition of nodes, making it somewhat infeasible for mobile computing applications. Some improved technologies are known to speed up processing capacity by shrinking the consensus group, increasing the block capacity and/or shortening the block interval. Even these solutions are met with major problems such as storage limitations and weak security. To face the realistic application scenarios for blockchain technology in the mobile realm, we propose a new public blockchain designed based on sharding, aggregate signature and cryptographic sortition which we call SAC. In SAC, the transaction rate increases with the number of shards while the length of the consensus signature is a constant. Meanwhile, in SAC, the assignment of consensus representatives is controlled by a verifiable random function, which can effectively solve the problem of centralized consensus. In addition, this paper analyzes the performance of SAC to give adequate comparison with other sharding technologies while also giving a rational security analysis. Our experimental results clearly show the potential applicability of this novel blockchain protocol to in mobile computation.

scholarly journals Thermochemical Heat Storage in a Lab-Scale Indirectly Operated CaO/Ca(OH)2 Reactor—Numerical Modeling and Model Validation through Inverse Parameter Estimation

2021 ◽  
Vol 11 (2) ◽  
pp. 682
Author(s):  
Gabriele Seitz ◽  
Farid Mohammadi ◽  
Holger Class
Keyword(s):  
Numerical Model ◽  
Gas Flow ◽  
Reaction Rate ◽  
Heat Storage ◽  
Bulk Material ◽  
Fixed Bed ◽  
Experimental Results ◽  
Fixed Bed Reactor ◽  
Thermochemical Heat Storage ◽  
Speed Up

Calcium oxide/Calcium hydroxide can be utilized as a reaction system for thermochemical heat storage. It features a high storage capacity, is cheap, and does not involve major environmental concerns. Operationally, different fixed-bed reactor concepts can be distinguished; direct reactor are characterized by gas flow through the reactive bulk material, while in indirect reactors, the heat-carrying gas flow is separated from the bulk material. This study puts a focus on the indirectly operated fixed-bed reactor setup. The fluxes of the reaction fluid and the heat-carrying flow are decoupled in order to overcome limitations due to heat conduction in the reactive bulk material. The fixed bed represents a porous medium where Darcy-type flow conditions can be assumed. Here, a numerical model for such a reactor concept is presented, which has been implemented in the software DuMux. An attempt to calibrate and validate it with experimental results from the literature is discussed in detail. This allows for the identification of a deficient insulation of the experimental setup. Accordingly, heat-loss mechanisms are included in the model. However, it can be shown that heat losses alone are not sufficient to explain the experimental results. It is evident that another effect plays a role here. Using Bayesian inference, this effect is identified as the reaction rate decreasing with progressing conversion of reactive material. The calibrated model reveals that more heat is lost over the reactor surface than transported in the heat transfer channel, which causes a considerable speed-up of the discharge reaction. An observed deceleration of the reaction rate at progressed conversion is attributed to the presence of agglomerates of the bulk material in the fixed bed. This retardation is represented phenomenologically by mofifying the reaction kinetics. After the calibration, the model is validated with a second set of experimental results. To speed up the calculations for the calibration, the numerical model is replaced by a surrogate model based on Polynomial Chaos Expansion and Principal Component Analysis.

scholarly journals The vibro-impact capsule system in millimetre scale: numerical optimisation and experimental verification

Meccanica ◽  
2020 ◽  
Vol 55 (10) ◽  
pp. 1885-1902
Author(s):  
Yang Liu ◽  
Joseph Páez Chávez ◽  
Jiajia Zhang ◽  
Jiyuan Tian ◽  
Bingyong Guo ◽  
...  
Keyword(s):  
Dynamical System ◽  
Mathematical Formulation ◽  
Path Following ◽  
Piecewise Smooth ◽  
Experimental Results ◽  
Scale Down ◽  
Speed Up ◽  
Small Bowel Endoscopy ◽  
Numerical Optimisation ◽  
Smooth Dynamical System

Abstract The vibro-impact capsule system has been studied extensively in the past decade because of its research challenges as a piecewise-smooth dynamical system and broad applications in engineering and healthcare technologies. This paper reports our team’s first attempt to scale down the prototype of the vibro-impact capsule to millimetre size, which is 26 mm in length and 11 mm in diameter, aiming for small-bowel endoscopy. Firstly, an existing mathematical model of the prototype and its mathematical formulation as a piecewise-smooth dynamical system are reviewed in order to carry out numerical optimisation for the prototype by means of path-following techniques. Our numerical analysis shows that the prototype can achieve a high progression speed up to 14.4 mm/s while avoiding the collision between the inner mass and the capsule which could lead to less propulsive force on the capsule so causing less discomfort on the patient. Secondly, the experimental rig and procedure for testing the prototype are introduced, and some preliminary experimental results are presented. Finally, experimental results are compared with the numerical results to validate the optimisation as well as the feasibility of the vibro-impact technique for the potential of a controllable endoscopic procedure.

scholarly journals Towards Secure Network Computing Services for Lightweight Clients Using Blockchain

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yang Xu ◽  
Guojun Wang ◽  
Jidian Yang ◽  
Ju Ren ◽  
Yaoxue Zhang ◽  
...  
Keyword(s):  
Service Providers ◽  
Security Analysis ◽  
Service Provisioning ◽  
Network Computing ◽  
Security Risks ◽  
Blockchain Technology ◽  
Computing Services ◽  
Viable Solution ◽  
Secure Network ◽  
Iot Devices

The emerging network computing technologies have significantly extended the abilities of the resource-constrained IoT devices through the network-based service sharing techniques. However, such a flexible and scalable service provisioning paradigm brings increased security risks to terminals due to the untrustworthy exogenous service codes loading from the open network. Many existing security approaches are unsuitable for IoT environments due to the high difficulty of maintenance or the dependencies upon extra resources like specific hardware. Fortunately, the rise of blockchain technology has facilitated the development of service sharing methods and, at the same time, it appears a viable solution to numerous security problems. In this paper, we propose a novel blockchain-based secure service provisioning mechanism for protecting lightweight clients from insecure services in network computing scenarios. We introduce the blockchain to maintain all the validity states of the off-chain services and edge service providers for the IoT terminals to help them get rid of untrusted or discarded services through provider identification and service verification. In addition, we take advantage of smart contracts which can be triggered by the lightweight clients to help them check the validities of service providers and service codes according to the on-chain transactions, thereby reducing the direct overhead on the IoT devices. Moreover, the adoptions of the consortium blockchain and the proof of authority consensus mechanism also help to achieve a high throughput. The theoretical security analysis and evaluation results show that our approach helps the lightweight clients get rid of untrusted edge service providers and insecure services effectively with acceptable latency and affordable costs.

scholarly journals ECLB: Edge-Computing-Based Lightweight Blockchain Framework for Mobile Systems

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Qingqing Xie ◽  
Fan Dong ◽  
Xia Feng
Keyword(s):  
Mobile Devices ◽  
Security Analysis ◽  
Edge Computing ◽  
Mobile Systems ◽  
Superior Performance ◽  
Consensus Protocol ◽  
Open Problems ◽  
Blockchain Technology ◽  
Natural Solution ◽  
And Performance

The blockchain technology achieves security by sacrificing prohibitive storage and computation resources. However, in mobile systems, the mobile devices usually offer weak computation and storage resources. It prohibits the wide application of the blockchain technology. Edge computing appears with strong resources and inherent decentralization, which can provide a natural solution to overcoming the resource-insufficiency problem. However, applying edge computing directly can only relieve some storage and computation pressure. There are some other open problems, such as improving confirmation latency, throughput, and regulation. To this end, we propose an edge-computing-based lightweight blockchain framework (ECLB) for mobile systems. This paper introduces a novel set of ledger structures and designs a transaction consensus protocol to achieve superior performance. Moreover, considering the permissioned blockchain setting, we specifically utilize some cryptographic methods to design a pluggable transaction regulation module. Finally, our security analysis and performance evaluation show that ECLB can retain the security of Bitcoin-like blockchain and better performance of ledger storage cost in mobile devices, block mining computation cost, throughput, transaction confirmation latency, and transaction regulation cost.

scholarly journals Privacy-Protection Scheme of a Credit-Investigation System Based on Blockchain

Entropy ◽  
2021 ◽  
Vol 23 (12) ◽  
pp. 1657
Author(s):  
Ke Yuan ◽  
Yingjie Yan ◽  
Tong Xiao ◽  
Wenchao Zhang ◽  
Sufang Zhou ◽  
...  
Keyword(s):  
Privacy Protection ◽  
Service Providers ◽  
Security Analysis ◽  
Cloud Service ◽  
Identity Authentication ◽  
Protection Scheme ◽  
Blockchain Technology ◽  
Searchable Symmetric Encryption ◽  
Verification Time ◽  
Identity Privacy

In response to the rapid growth of credit-investigation data, data redundancy among credit-investigation agencies, privacy leakages of credit-investigation data subjects, and data security risks have been reported. This study proposes a privacy-protection scheme for a credit-investigation system based on blockchain technology, which realizes the secure sharing of credit-investigation data among multiple entities such as credit-investigation users, credit-investigation agencies, and cloud service providers. This scheme is based on blockchain technology to solve the problem of islanding of credit-investigation data and is based on zero-knowledge-proof technology, which works by submitting a proof to the smart contract to achieve anonymous identity authentication, ensuring that the identity privacy of credit-investigation users is not disclosed; this scheme is also based on searchable-symmetric-encryption technology to realize the retrieval of the ciphertext of the credit-investigation data. A security analysis showed that this scheme guarantees the confidentiality, the availability, the tamper-proofability, and the ciphertext searchability of credit-investigation data, as well as the fairness and anonymity of identity authentication in the credit-investigation data query. An efficiency analysis showed that, compared with similar identity-authentication schemes, the proof key of this scheme is smaller, and the verification time is shorter. Compared with similar ciphertext-retrieval schemes, the time for this scheme to generate indexes and trapdoors and return search results is significantly shorter.

scholarly journals A Novel Image Encryption Algorithm Based on DNA Subsequence Operation

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Qiang Zhang ◽  
Xianglian Xue ◽  
Xiaopeng Wei
Keyword(s):  
Image Encryption ◽  
Chaotic Map ◽  
Security Analysis ◽  
Experimental Results ◽  
Encryption Algorithm ◽  
Secret Key ◽  
Logistic Chaotic Map ◽  
Image Encryption Algorithm

We present a novel image encryption algorithm based on DNA subsequence operation. Different from the traditional DNA encryption methods, our algorithm does not use complex biological operation but just uses the idea of DNA subsequence operations (such as elongation operation, truncation operation, deletion operation, etc.) combining with the logistic chaotic map to scramble the location and the value of pixel points from the image. The experimental results and security analysis show that the proposed algorithm is easy to be implemented, can get good encryption effect, has a wide secret key's space, strong sensitivity to secret key, and has the abilities of resisting exhaustive attack and statistic attack.

scholarly journals Simulation and Analysis of OSPFv2 Neighbor Authentication Based on GNS

2012 ◽  
Vol 6-7 ◽  
pp. 876-881
Author(s):  
Xiao Hua Li ◽  
Xian Gang Zhao ◽  
Ren Long Zhang ◽  
Shu Yan Xu ◽  
Li Yang
Keyword(s):  
Shortest Path ◽  
Network Topology ◽  
Security Analysis ◽  
Experimental Results ◽  
Functional Verification ◽  
Information Release ◽  
Packet Header ◽  
Network Safety ◽  
Normal Work

Routing information release is a kind of promise from the router for network reachability. Illegal routing information may have disastrous effects on the normal work of the network. Open Shortest Path First (OSPF) protocol provides authentication methods to protect the authenticity and integrity of the routing traffic. This paper describes two authentication types of OSPFv2, analyzes the realization mechanism and packet header format of each authentication respectively. Based on GNS3, a typical network topology was designed, and with the aid of it we carried out functional verification and security analysis. The simulation can provide a reference for building an OSPF network. Experimental results show that the configuration of OSPFv2 routing authentication can effectively prevent the router from receiving unauthorized or malicious routing updates, thereby improving network safety.

scholarly journals Reconstruction of Generative Adversarial Networks in Cross Modal Image Generation with Canonical Polyadic Decomposition

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Ruixin Ma ◽  
Junying Lou ◽  
Peng Li ◽  
Jing Gao
Keyword(s):  
Mobile Terminal ◽  
Experimental Results ◽  
Generative Adversarial Networks ◽  
Image Generation ◽  
Adversarial Networks ◽  
Speed Up ◽  
Canonical Polyadic Decomposition

Generating pictures from text is an interesting, classic, and challenging task. Benefited from the development of generative adversarial networks (GAN), the generation quality of this task has been greatly improved. Many excellent cross modal GAN models have been put forward. These models add extensive layers and constraints to get impressive generation pictures. However, complexity and computation of existing cross modal GANs are too high to be deployed in mobile terminal. To solve this problem, this paper designs a compact cross modal GAN based on canonical polyadic decomposition. We replace an original convolution layer with three small convolution layers and use an autoencoder to stabilize and speed up training. The experimental results show that our model achieves 20% times of compression in both parameters and FLOPs without loss of quality on generated images.

scholarly journals An Approach Inspired by Simulation Points to Accelerate Smart Cities Simulations

2021 ◽  
Author(s):  
Francisco Wallison Rocha ◽  
Emilio Francesquini ◽  
Daniel Cordeiro
Keyword(s):  
Time Series ◽  
Standard Deviation ◽  
Smart Cities ◽  
Experimental Results ◽  
Average Error ◽  
Original Series ◽  
Speed Up ◽  
Simulation Results

Approaches using simulations are of great value for smart cities research. However, city-scale simulators can be both processing and memory-intensive, and hard to scale. To speed up these simulations and to allow executing larger scenarios, this work presents an approach based on an technique named Simpoint to estimate the result of new simulations using previous simulations. This technique aims to identify and cluster recurring patterns during a simulation. Then, unique representatives of each cluster are selected and their simulation is used to estimate the simulation results of the remaining cluster elements. The experimental results for our estimates are promising.On a dataset with 16,993 time series, our technique was able to estimate the original series with an average error of 1.60979e-11 and standard deviation of 9.18228e-11.

scholarly journals Application-Level Interoperability for Blockchain Networks

2021 ◽  
Author(s):  
Mohammad Madine ◽  
Khaled Salah ◽  
Raja Jayaraman ◽  
Yousof Al-Hammadi ◽  
Junaid Arshad ◽  
...  
Keyword(s):  
Medical Record ◽  
Security Analysis ◽  
Data Provenance ◽  
Smart Contracts ◽  
Shared Data ◽  
The Core ◽  
Blockchain Technology ◽  
Detailed Explanation ◽  
Share Data ◽  
Inter Communication

Blockchain technology has the potential to revolutionize industries by offering decentralized, transparent, data provenance, auditable, reliable, and trustworthy features. However, cross-chain interoperability is one of the crucial challenges preventing widespread adoption of blockchain applications. Cross-chain interoperability represents the ability for one blockchain network to interact and share data with another blockchain network. Contemporary cross-chain interoperability solutions are centralized and require re-engineering of the core blockchain stack to enable inter-communication and data sharing among heterogeneous blockchain networks. In this paper, we propose an application-based cross-chain interoperability solution that allows blockchain networks of any architecture type and industrial focus to inter-communicate, share data, and make requests. Our solution utilizes the decentralized applications as a distributed translation layer that is capable of communicating and understanding multiple blockchain networks, thereby delegating requests and parameters among them. The architecture uses incentivized verifier nodes that maintain the integrity of shared data facilitating them to be readable by the entities of their network. We define and describe the roles and requirements of major entities of inter-operating blockchain networks in the context of healthcare. We present a detailed explanation of the sequence of interactions needed to share an Electronic Medical Record (EMR) document from one blockchain network to another along with the required algorithms. We implement the proposed solution with Ethereum-based smart contracts for two hospitals and also present cost and security analysis for the cross-chain interoperability solution. We make our smart contracts code and testing scripts publicly available.

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