Attribute-based keyword search (ABKS) achieved significant attention for data privacy and fine-grained access control of outsourced cloud data. However, most of the existing ABKS schemes are designed based on a semi-honest and curious cloud storage system in which the search fairness between two parties becomes questionable. Hence, it is vital to building a protocol that provides mutual trust between the cloud and its users. This paper proposes a blockchain-aided keyword search over encrypted data, which achieves search fairness between the cloud and its users using Ethereum blockchain and smart contracts. Additionally, the system accomplishes fine-grained access control, limiting access to the data to only those who have been given permission. Besides, the scheme allows multi keyword search by the users. The security analysis shows that our scheme is indistinguishable against chosen-plaintext attack and other malicious attacks. The performance analysis shows that the scheme is efficient.