Abstract

۱٫ Introduction

۲٫ Overview of blockchain history

۳٫ Blockchain Technology

۴٫ Blockchain Applications

۵٫ Security risks and attacks with blockchain

۶٫ Security measures for blockchain

۷٫ Challenges and research trends

۸٫ Related work

۹٫ Conclusion

Conflict of interest

References

Abstract

     Blockchain is a technology that has desirable features of decentralization, autonomy, integrity, immutability, verification, fault-tolerance, anonymity, auditability, and transparency. In this paper, we first carry out a deeper survey about blockchain technology, especially its history, consensus algorithms’ quantitative comparisons, details of cryptography in terms of public key cryptography, Zero-Knowledge Proofs, and hash functions used in the blockchain, and the comprehensive list of blockchain applications. Further, the security of blockchain itself is a focus in this paper. In particular, we assess the blockchain security from risk analysis to derive comprehensive blockchain security risk categories, analyze the real attacks and bugs against blockchain, and summarize the recently developed security measures on blockchain. Finally, the challenges and research trends are presented to achieve more scalable and securer blockchain systems for the massive deployments.

Introduction

     In blockchain, data are kept in a distributed ledger. It is the blockchain technology to provide integrity and availability that allows participants in the blockchain network to write, read, and verify transactions recorded in a distributed ledger. However, it does not allow the deletion and modification operations on the transactions and other information stored on its ledger. The blockchain system is supported and secured by cryptographic primitives and protocols, e.g., digital signatures, hash functions, etc. These primitives guarantee the transactions that are recorded into the ledger are integrity-protected, authenticity-verified, and non-repudiated. Further, as a distributed network, to allow the entire set of participants to agree on a unified record, the blockchain technology also needs a consensus protocol, which is essentially a set of rules to be followed by every participant, in order to achieve a globally unified view.

     In a trustless environment, blockchain provides users with desirable features of decentralization, autonomy, integrity, immutability, verification, fault-tolerance, attracted great academic and industrial attention in the recent few years, anonymity, auditability, and transparency [[1], [2], [3]]. With these advanced features, blockchain technology has attracted great academic and industrial attention in the recent few years.

Conclusion

     This paper has first conducted a deeper survey on blockchain technology in terms of overview, consensus algorithms, smart contracts, and cryptography for blockchain. It presented the history of blockchain, and compared the five most common consensus algorithms and one most different consensus algorithm in as much detail and quantitative as possible. Public key cryptography, Zero-Knowledge Proof, and hash functions used in blockchain have been described in detail for integrity, authentication, nonrepudiation, and payment address required in blockchain systems. This paper has then listed the comprehensive applications of blockchain. It has further presented the rich information and comparisons of eight cryptocurrencies as the first blockchain application, supply chain as a widely used case, and Smart Dubai Office as the first whole government service application. Further, the security of blockchain itself is a focus in this paper. It has described the comprehensive security risks categories based on the Top 10 Web Application Security Risks, low level risks, and high level risks. It has surveyed many real attacks and bugs on blockchain systems and listed out their root causes. The paper has then presented the security measures in the areas of security analysis, detecting malicious codes & bugs, software codes security, privacy preserving, and so on. Specially, it has presented and compared eleven smart contract bytecode vulnerability analysis tools. Finally, the challenges and research trends have been presented to build more scalable and securer blockchain systems for massive deployments.