Due to the urgent requirement to achieve secure communication between service providers (SPs) and smart meters (SMs), including reliable mutual authentication and privacy credentials, key management is critical in smart grids. Recently, a number of key management schemes have been proposed. However, schemes based on trusted third parties (TTPs) become insecure if the TTP fails. Furthermore, the SPs in most schemes are centralized to manage their respective SMs, which involve a single point of failure. Furthermore, SPs cannot monitor each other for data traceability or security auditing. To remedy these inadequacies, we propose a decentralized keyless signature scheme based on a consortium blockchain to realize more efficient and secure key management. The SM sends requests and receive responses using a blockchain network for data transmission operations. We designed a decentralized secure consensus mechanism that turns a blockchain into an automated access-control manager that does not require a TTP or trust anchor. The SPs of the proposed scheme can keep each other in check using the blockchain. In our concluding remarks, we describe how the proposed scheme incurs smaller computational time costs and is both cost-effective and scalable. (C) 2019 Elsevier Ltd. All rights reserved.