Privacy Preserving Fingerprint Authentication based on Homomorphic Encryption and Blockchain

Abstract

Biometric authentication methods generally rely on centralized authority such as centralized database servers to store biometric templates and manage authentication. These methods suffer from different points of attack. If the central entity is compromised, the system becomes vulnerable and unable to ensure integrity of stored templates. This paper proposes a distributed scheme of biometric authentification, eliminating the need for a central entity. The proposal is based on the Ethereum blockchain, which offers decentralized and irreversible properties for the storage and management of biometric templates. For each user, the fingerprint template is encrypted using homomorphic encryption and stored on the smart card. The hashed encrypted vector is then stored on the blockchain to ensure its confidentiality. Our proposed scheme, allows authentication of users using a smart contract, while the distance calculation is performed on the encrypted domain that achieves the integrity of the calculation results. By using hashed vectors, the proposal is efficient and cost-effective. These improvements provide solutions to many problems in biometric systems such as template modification, channel interception, and override comparator.