Privacy-Preserving eIDAS Compliance in Blockchain Wallets via zkVM

The paper presents a system that enables the use of eIDAS-compliant digital signatures (CMS/PKCS#7) to authorize smart contract operations on the blockchain, while preserving user privacy. The system leverages a zkVM to generate verifiable proofs of signature verification (in around 1 min) without exposing sensitive data onchain. We show an example use case for national tax refunding based on a tax ID smart contract wallet where proof verification and transfer costs are negligible (≈ $0.1). Our work demonstrates promise for bridging PKI-based identity systems with public blockchains.