Secure User Authentication with Secret Sharing and Smart Contract for Permissioned Blockchain

Abstract

Blockchains (BCs) have garnered attention owing to their potential applications in a wide range of fields, including finance and the Internet of Things. Nakajima et al. introduced a secure and decentralized storage system using a permissioned BC and secret sharing. However, this method employs conventional password-based user authentication with a single SDK server. In this study, we introduce a secure and decentralized user authentication system that employs secure computation based on Shamir’s (2,2) threshold secret sharing and smart contracts. We demonstrate that employing secure computation using secret sharing facilitates user authentication while maintaining the confidentiality of the original password. Furthermore, we show that even if the information registered on the SDK server is known, an attacker will not be able to recover the original password.