A survey of security threats and defense on Blockchain

摘要

Blockchain provides a trusted environment for storing information and propagating transactions. Owing to the distributed property and integrity, blockchain has been employed in various domains. However, lots of studies prove that the security mechanism of blockchain exposes its vulnerability especially when the blockchain suffers attacks. This work provides a systematic summary of the security threats and countermeasures on blockchain. We first review the working procedure and its implementation techniques. We then summarize basic security properties of blockchain. From the view of the blockchain's architecture, we describe security threats of blockchain, including weak anonymity, vulnerability of P2P network, consensus mechanism, incentive mechanism and smart contract. We then describe the related attacks and summarize the current representative countermeasures which improve anonymity and robustness against security threats respectively. Finally, we also put forward future research directions on consensus, incentive mechanisms, privacy preservation and encryption algorithm to further enhance security and privacy of the blockchain-based multimedia.