HSchain: Anonymous Permissioned Blockchain with Enhanced Auditability

Abstract

Anonymity and auditability of transactions are two important but conflicting requirements for many blockchain-based applications. Technologies proposed to realize anonymous transactions, such as coin mixing and ring signature, make it hard to identify the participants of transactions. In this paper, we propose a system called HSchain, which enables the regulator to identify the participants while keeping the identity information hidden from nodes in the blockchain network. The proposed system uses the ring signature and the one-time public key to hide the sender and the receiver of a transaction respectively. By running a secret handshake protocol with the regulator, the sender/receiver generates a tag which is attached to the transaction to make it auditable. We carefully design the structure of the tag so that only the regulator can determine if a user has participated in a specific transaction. Simulation results demonstrate that adding such a tag to an anonymous transaction does not incur much overhead.