Transaction-Level Blockchain Rewrites with Revocation and Traceability Using Attribute-Based Cryptosystems

In this article, we study efficient and authorized rewriting of transactions already written to a blockchain. Mutable transactions will make a fraction of all blockchain transactions, but will be a necessity to meet the needs of privacy regulations, such as the General Data Protection Regulation (GDPR). The state-of-the-art rewriting approaches have several shortcomings, such as lack of user anonymity, inefficiency, and absence of revocation mechanisms for entities authorized to mutate transactions. To address this challenge we present \(\mathsf{ReTRACe}\) , an efficient framework for blockchain rewrites. \(\mathsf{ReTRACe}\) is designed by composing a revocable chameleon hash scheme with an ephemeral trapdoor, a revocable fast attribute based encryption scheme, and a dynamic group signature scheme. In this article, (i) we discuss \(\mathsf{ReTRACe}\) and its constituent primitives in detail, (ii) present security analyses of the primitives, and (iii) present experimental results to demonstrate the scalability of \(\mathsf{ReTRACe}\) .