Towards Decentralized Autonomous Digital Signatures Using Smart Contracts

Owing to the spread of COVID-19, the digitalization of various services is rapidly being promoted. In particular, online services such as obtaining a digital certificate (e.g., digital signature) from an authority are becoming increasingly important. Therefore, systems that can autonomously generate digital signatures are urgently required. However, the autonomous generation of signatures is difficult because the secret key for signatures must be strictly managed. Moreover, a decentralized autonomous systems should be publicly verifiable. Thus, schemes that preclude strict control of the secret key are desirable. In this study, we propose a new decentralized scheme that autonomously generates a digital signature without a secret key, using blockchain-based smart contracts. The fundamental concept behind our scheme is to eliminate secret keys by leveraging the closed nature of the processing operations of smart contracts within the blockchain; thus, the process of generating signatures and their output values satisfies the condition of immutability. Finally, we perform a security evaluation and feasibility study of our proposed scheme and show that it works securely on the Ethereum blockchain.