In today’s rapidly evolving data environment, secure and efficient storage solutions are fundamental to supporting the robust development of the data economy. Trustworthy data space serves as an innovative technological framework for addressing critical challenges in data circulation. It is specifically designed to facilitate the secure exchange in data elements and overcome trust barriers in cross-organizational data sharing. However, current decentralized storage architectures still have significant implementation gaps. Practical deployment and system integration remain substantial challenges for existing technological solutions. To address these issues, this paper first conducts a systematic analysis of existing trusted data storage methods. On this basis, it proposes a data-secure storage mechanism based on polynomial commitment. This mechanism uses polynomial commitment to implement data storage and verification, thereby ensuring data integrity and consistency. Meanwhile, it integrates homomorphic signature technology to guarantee the authenticity of data sources without disclosing original data. Additionally, a data modification recording function is introduced to ensure the traceability of all operations. Experimental results show that the proposed scheme achieves superior performance in three key aspects: communication overhead, storage efficiency, and data update costs.

Blockchain oracles bridge on-chain smart contracts and off-chain data sources, but encrypted off-chain data still raises two practical challenges: how to verify retrieval integrity without exposing sensitive values, and how to keep verification information fresh when the off-chain data set changes. Existing oracle and outsourced-database retrieval mechanisms often rely on plaintext verification, heavy cryptographic proofs, or static authentication structures, which limits their applicability to latency-sensitive IoT and decentralized finance scenarios. To address these issues, this paper proposes a retrieval integrity verification mechanism based on CKKS approximate homomorphic encryption and an authenticated index named CKKS-Auth Tree. The proposed mechanism verifies encrypted query results through homomorphically aggregated metadata, while smart contracts record versioned verification commitments to detect stale or replayed results after updates. The scope of the mechanism is the integrity, completeness, privacy, and freshness of data after commitment and upload; verifying the physical authenticity of the original data source is outside the core threat model. Experimental results show that the proposed scheme reduces authentication and verification overhead compared with existing retrieval verification methods while supporting encrypted metadata updates and on-chain synchronization.