ACT: Auditable Confidential Transaction Scheme

Cryptographic techniques are important means for blockchain privacy protection. However, strong privacy protection and transaction data audit are two conflicting requirements of stakeholders and organizations in the blockchain. Therefore, considering the lack of auditing of private cryptocurrency, an auditable confidential transaction (ACT) scheme is proposed. In ACT scheme, digital signature is used to authenticate the source of audit request, and bulletproofs is used to aggregate range proof to improve the efficiency of transaction generation. Homomorphic encryption ensures that the auditor only knows the total amount of transaction of all users in the network for a period of time, while protecting the privacy of individual user’s transaction amount. Through zero knowledge proof, the privacy and correctness of transaction data are guaranteed. The security proof shows that ACT scheme satisfies auditability, audit reliability and transaction amount privacy. The experiment results show that the generation and verification efficiency of transaction via bulletproofs are improved, and the execution efficiency of the auditor’s algorithm as well.