Decentralised Redactable Blockchain: A Privacy-Preserving Approach to Addressing Identity Tracing Challenges

Blockchain is an immutable and distributed ledger managed by all participants, enhancing data transparency and safety. Immutability is a crucial factor in ensuring data transparency and safety. However, there is a significant demand for redaction of the ledger due to security and privacy concerns. In this paper, we propose a redactable blockchain solution based on meta-transactions using zk-SNARK to improve anonymity in a decentralised manner. A one-time cryptographic key generation scheme, designed for a signature generation scheme, produces different keys for each transaction to enhance security and privacy by preventing identity tracing. We also employ zk- SNARK to hide the information of cryptographic keys and signatures. The modification history for each transaction is linked together, and the verification time is significantly short, around 10 msec, even when transactions have multiple modifications. Furthermore, we introduce a redaction fee scheme for transaction owners to maintain concise modification histories encouraging removal instead of modification to minimise the performance overhead associated with this redaction approach. Index Terms—redactable blockchain, blockchain redaction, zksnarks