Biometrics Enhances Blockchain Wallet Governance

The provision of non-custodial wallets is spreading to achieve governance by users. However, the key management of non-custodial wallets is immature, making it difficult to handle situations such as loss or user death effectively. While multi-signature wallets and Multi-Party Computation (MPC) wallets provide redundancy and enable backup and inheritance, users remain burdened with key management. Biometrically Independent Fuzzy Signature (BIFS) simplifies key management by using biometric information as one of the distributed keys. However, BIFS supports only specific signature schemes and is not compatible with signature schemes used on blockchains. This paper presents two main contributions. First, we demonstrate the practicality of the BIFS scheme in blockchain wallets. We extend BIFS to support two-party distributed signatures with additive-distributed keys, making it compatible with digital signature schemes commonly used in blockchain, such as the Elliptic Curve Digital Signature Algorithm (ECDSA) or the Schnorr Signatures. Experimental evaluations show that signatures are generated in milliseconds without compromising the accuracy of biometric authentication. Second, we propose a BIFS-based wallet that offers secure and convenient key management and backup. Our backup method generates different distributed key pairs without restoring the signing key, minimizing key leakage risks and facilitating cryptocurrency inheritance.