As a key technology for building trust networks and implementing value interconnections, blockchain has received extensive attention. There are numerous technical use cases for blockchains in a variety of areas, such as digital currency systems, Internet of Things (IoT), smart grids, supply blockchain and finance. However, the widespread application of blockchain also encounters many security and privacy issues. This article presents an overview and analysis of privacy protection, security supervision and data exchange in blockchain-based applications, providing a comprehensive analysis of the wide application of blockchain. Moreover, blockchain's future research directions and development trends are discussed.
A centralized management mechanism suffers from a single point of failure problem. When the centralized node is destroyed, the system crashes. Decentralized blockchains can solve this problem without the need for a trusted third party. Blockchains are considered to be a breakthrough in secure computing that does not require central authorization . Generally, a blockchain is a distributed database that packs changing transactions into blocks, where a blockchain structure is formed between the blocks. From a security point of view, blockchains run on a peer-to-peer (P2P) overlay network, utilizing consensus mechanisms and cryptographic algorithms to ensure their security .
With the widespread popularity of digital cryptocurrencies such as Bitcoin, blockchains have attracted widespread attention from governments, regulators, financial institutions, technology companies, etc. . Blockchains are considered a promising solution to the problems of secure storage, sharing and analysis of data, trusted network control and resource management. Thus, blockchains have deeply penetrated people’s daily lives and work through cryptocurrency, digital finance, supply chains, smart cities and the Internet of Things (IoT) .
With the introduction of smart contracts, blockchains were endowed with programmable features. Therefore, the application field for blockchains is becoming increasingly extensive, which is conducive for the interconnection of value. However, due to the immature technologies and the imperfect management of blockchains, they face many problems. In terms of security, there are still many attacks against blockchain consensus mechanisms, smart contracts, data content, etc., such as 51% attacks, smart contract vulnerabilities and denial of service attacks . Moreover, a set of formal regulatory rules and mechanisms have not yet been formed for illegal data on blockchains. In terms of privacy protection, blockchains need to disclose the transaction information for an entire network to allow the nodes in the network to reach a consensus, which creates a risk of privacy leakage.
As distributed ledgers, blockchains are decentralized, tamper-resistant, open and transparent, and they are accelerating the application pace in finance, medical care, manufacturing and other industries. However, there are still many problems and challenges in the theory and application of blockchains as a whole. This paper discussed the latest progress in blockchain supervision, privacy and other challenges in recent years, and systematically elaborated and analyzed the technologies involved. Through research on security supervision, privacy protection and data exchange, some problems for the current blockchains were summarized. This paper also proposed future research directions, hoping to provide more possibilities for further blockchain advancements.