<p>Cloud-assisted data sharing has become the preferred approach for data exchange. Despite its popularity, the loss of physical control over outsourced data has intensified data owners’ concerns regarding data privacy and security. Existing attribute-based encryption schemes achieve fine-grained access control, but face an efficiency-security trade-off in policy updates, key privacy leakage risks, and a lack of proactive periodic integrity verification, limiting their practical application. To address these issues, this paper proposes EPPCDS, an efficient privacy-preserving cloud data sharing scheme with blockchain-assisted access control and periodic integrity checking. EPPCDS implements key-level fine-grained access control via multi-keyword searchable encryption for low-overhead secure policy updates, and adopts a double-layer digital envelope mechanism combined with certificateless cryptography and identity randomization to protect decryption tokens and user identity privacy. It also integrates provable data possession with a deposit-based reward-penalty mechanism to realize proactive periodic integrity verification. We conduct a thorough security analysis confirming EPPCDS satisfies diverse security demands in cloud data sharing. Extensive experiments on a Hyperledger Fabric prototype demonstrate that EPPCDS incurs low runtime overhead for all participating parties and outperforms representative existing schemes in terms of policy creation, policy update, and data access efficiency.</p>