AudiTEE: Efficient, General-Purpose and Privacy-Preserving Audit for Distributed Ledgers

Abstract

Privacy-preservation and effective auditing are two desirable but challenging requirements on distributed ledgers. To meet the requirements, this paper presents an auditing scheme, called as AudiTEE, which can audit a distributed ledger in a generic, efficient, and privacy-preserving manner. AudiTEE leverages Trusted Execution Environment (TEE) to generate confidential but auditable transactions and realize arbitrary, efficient and confidential audit on them. Unfortunately, TEE suffers from some inherent barriers and is itself not a complete solution for fast audit. To tackle these challenges, AudiTEE takes advantage of KAMT (K-anonymity Authentication Based on Merkle Tree) protocol for efficient management on account and user-defined anonymous transactions. Further, to achieve a complete and fast audit with unlinkability, TEE doesn't process through all but only a comparatively small part of transactions according to a special ktag attached on each transaction to ensure that a user cannot hide transactions from auditor even when auditor is blind with who is involved in each transaction on the ledger. Apart from the above, AudiTEE allows flexible control on user behaviors. We implement a concrete instance of AudiTEE under a bank setting and demonstrate the scalability with all its core functionalities.