A Blockchain-Based MFA Model for Decentralization, Privacy, and Asymmetric-Key Security

Abstract

Authentication processes are fundamental for service providers and users alike. Currently, many users rely on centralized identity providers that verify identities to grant access to services. While these providers offer convenience, they require the disclosure of personal data, often leading to privacy concerns and third-party data access. Advancements in blockchain technology and smart contracts have enabled decentralized alternatives. Specifically, Sign-In with Ethereum (SIWE) leverages asymmetric cryptography, allowing users to authenticate via their public addresses and wallets. However, this approach introduces a significant risk: the loss or theft of private keys can result in the permanent loss of account control. This document proposes a multi-factor authentication (MFA) scheme that utilizes a smart contract to link a primary blockchain address with a secondary factor. This system provides an additional security layer against attackers without requiring personal information, effectively balancing account recovery resilience with user privacy.