Privacy-Preserving Transaction Admission with Warrant-Based Trace Recovery for Regulated Cryptocurrency Transactions

Public blockchain transactions need compliance support without exposing stable identity anchors. This paper presents a privacy-preserving transaction admission framework for regulated cryptocurrency transaction paths. It adds an admission and recovery layer to admission-aware applications, contracts, gateways, or chain policies without introducing a new cryptocurrency. In ordinary use, a user submits a public transaction object and a single Groth16 admission proof, which checks registration membership, current state, hidden home-domain membership, hidden home-domain policy compliance, transaction binding, replay control, and trace-object well-formedness while hiding identity-related witnesses. When a valid warrant targets an accepted transaction, recovery committees perform transaction-scoped trace recovery through outer opening and domain-local inner recovery. We implement an end-to-end prototype with off-chain modules and an Ethereum Virtual Machine (EVM)-compatible public admission contract. The evaluation reports a 28,370-constraint circuit, 3.40 s average proving time, about 536k local EVM admission gas, 30/30 replay rejection, 8.46 ms local layered recovery latency, and 3.84 ms domain-dispatch latency.