In this paper, we present a generic approach of designing redactable blockchain protocol in the permissionless setting with instant redaction, applied to both proof-of-stake blockchain and proof-of-stake blockchain with just different instantiations to randomly select ``committees'' according to stake or computational power. Our protocol can achieve the security against 1/2 (mildly adaptive) adversary bound, which is optimal in the blockchain protocol. It also offers public verifiability for redactable chains, where any edited block in the chain is publicly verifiable. Compared to previous solutions in permissionless setting, our redaction operation can be completed instantly, even only within one block in synchronous network, which is desirable for redacting harmful or sensitive data. Moreover, our protocol is compatible with most current blockchains requiring only minimal changes. Furthermore, we define the first ideal functionality of redactable blockchain following the language of universal composition, and prove that our protocol can achieve the security property of redactable common prefix, chain quality, and chain growth. Finally, we develop a proof-of-concept implementation, and conduct extensive experiments to evaluate the overhead incurred by redactions. The experimental results show that the overhead remains minimal for both online nodes and re-spawning nodes, which demonstrates the high efficiency of our design.
Category / Keywords: applications / Blockchain; Redactable Blockchain; Instant redaction Date: received 27 Feb 2021 Contact author: xujing at iscas ac cn,xinyuli1920@gmail com,yinlingyuan@tca iscas ac cn,luyuan@tca iscas ac cn,qiang tang@sydney edu au,zfzhang@tca iscas ac cn Available format(s): PDF | BibTeX Citation Version: 20210302:202641 (All versions of this report) Short URL: ia.cr/2021/223