关键词: 区块链, 分布式账本, P2P网络, 非对称加密, 共识机制, 智能合约

Abstract: Blockchain, both the cryptocurrency and the underlying Bitcoin technology, have attracted significant attention around the world. The reason is that blockchain is a decentralization technology with Consensus Trust Mechanism (CTM), which is obviously different from the traditional centralization system with Outer Trust Mechanism (OTM). This has made a great influence on the trust mechanism of people and promoted the usage of security technology in the blockchain. In this paper, we present the security architecture and key technologies of the blockchain, and explain how the blockchain ensure the integrity, non repudiation, privacy, consistency for the stored data through P2P network, distributed ledger, asymmetric encryption, consensus mechanism and smart contracts. Moreover, we analyze some new security threats and measures, for example, the preventing technology of Denial of Service (DoS) attack against the Transaction Storm (TS), the cryptographic access control (CAC) technology to enhance the data privacy, the key management technology against losing and stealing of digital asset, and so on. We also discuss the future security problems and technologies that might be discovered after the blockchain syncretizes new technologies, including, AI, Big Data, IOT, cloud computing, mobile Internet technologies.

Key words: blockchain, distributed ledger, P2P network, asymmetric encryption, consensus mechanism, smart contracts