Paper 2026/513

zkBSA: Auditable and Compliant Stealth Addresses for Blockchains

Abstract

Stealth addresses provide receiver unlinkability on blockchains, but existing schemes do not support regulatory compliance in settings where transaction amounts are transparent and recipient identities should remain private. We present zkBSA, a modular framework for auditable and compliant stealth addresses. zkBSA combines a stealth address scheme, public-key encryption, a whitelist commitment, and zero-knowledge proofs to enable on-chain verification that a transaction targets a whitelisted receiver without revealing which receiver was chosen. At the same time, authorized auditors can recover receiver-linked audit information. We formalize security in terms of public-transcript receiver unlinkability, compliance soundness, and audit correctness, and show that these properties follow from standard assumptions on the underlying primitives. We implement a proof of concept using ERC-5564, EC-ElGamal, Merkle trees, and RISC Zero zkVM. Our evaluation shows proof generation under 5.3 seconds for whitelist sizes up to $2^{24}$ and a fixed on-chain verification cost of about 235k gas, indicating that zkBSA is practical for receiver-private, compliance-enforced blockchain transactions.