Secure Passwordless Authentication Using Blockchain: A Cryptographic Challenge-Response Approach

Traditional web authentication mechanisms depend heavily on centralized password storage, which introduces signif- icant vulnerabilities including data breaches, credential stuffing attacks, and phishing threats. This research presents a novel pass- wordless authentication framework that utilizes the non-custodial cryptographic identity capabilities of modern Ethereum wallets combined with an immutable public key registry implemented through blockchain smart contracts. Our approach fundamen- tally transforms conventional username-password validation into a secure cryptographic challenge-response protocol. The backend server generates unique, session-specific challenge strings that users sign locally using their private keys through browser wallets. Signature verification against registered public addresses enables robust, tamper-resistant authentication without exposing private keys, storing passwords, or depending on centralized secret management systems. This architecture significantly en- hances security while maintaining user convenience and system integrity.