A Trusted Transaction Method for Remote Sensing Image Data Based on a Homomorphic Encryption Watermark and Blockchain

Existing methods for the secure transaction and circulation of remote sensing image data primarily focus on post-event investigation, lacking a reliable mechanism for secure distribution and fair trading of data. To address this issue, this study proposes a trusted transaction method that integrates a watermark based on Paillier homomorphic encryption, blockchain, and smart contract. This method leverages the homomorphic property of the Paillier cryptosystem to imperceptibly embed the ciphertext of the watermark generated from transaction information into encrypted remote sensing image data. The data buyer at the receiving end decrypts the key pair using the private key, thereby decrypting the data to obtain the watermarked plaintext. Simultaneously, transaction records are immutably stored on trusted blockchain nodes via smart contracts. Throughout the entire transaction process, data encryption/decryption and watermark embedding/extraction are symmetric. The experimental results demonstrate that the watermark can be effectively extracted after encryption, thereby supporting transaction verification and traceability. Furthermore, the three smart contracts designed in this study all exhibit strong execution performance. In particular, the smart contract employed for verification demonstrated an average execution latency of only 0.19 s per instance. Through enforcing the retrieval of parameters and storage credentials from the blockchain, the proposed method effectively constrains malicious behavior from both parties, offering a novel technical approach to facilitate consensus and mutual trust.