Auditable zerocoin scheme with user awareness

Abstract

With the development of Blockchain, more and more distributed cryptocurrencies continue to emerge. Most of these currencies use cryptographic techniques (such as zero-knowledge proofs, ring signatures, etc.) to enhance privacy protection, but at the same time the regulatory authorities have no access to audit transactions. Most existing auditing schemes are based on centralized system and cannot be directly applied to distributed cryptocurrencies. Therefore, an Auditable Zerocoin with User Awareness (AZUA) scheme which supports privacy protection and auditability simultaneously is proposed in this paper. Aiming to ensure that auditors can audit Zerocoin's transactions, auditability is defined in this paper. Meanwhile, in order to prevent auditors from abusing their power, a new security property is proposed: user awareness auditing. Moreover, taking transaction privacy issue into consideration, indistinguishability of audit information is defined. The transaction auditing from auditors is achieved in AZUA through the encryption scheme, which ensures the honesty of the auditors by introducing a commitment mechanism and that the users can be aware of whether they have been audited according to randomized public keys. Finally, it is proved that the scheme can satisfy auditability, user awareness auditing and indistinguishability of audit information simultaneously.