Database authentication watermarking scheme in encrypted domain

Digital watermarking in encrypted domain is a potential technology for privacy protection (with encryption) and integrity authentication (with watermark) in cloud computing environments. Based on order-preserving encryption scheme (OPES), discrete cosine transformation (DCT), cryptography hash and watermarking technologies, this study proposes a new database authentication watermarking scheme in encrypted domain. Firstly, data in a database are encrypted with OPES for privacy protection. Then, the encrypted data are divided into groups for DCT operations. The watermark bits generated by hashing AC coefficients are embedded into DC coefficients for integrity authentication of the encrypted data. In receiver, whether the data have been tampered can be claimed by matching the hash value of AC coefficients and the extracted watermark information from DC coefficients. The watermark embedding process in encrypted domain is lossless to plaintext data by exploring order-preserving property of OPES. In the receiver, an illegal user can recover the original database by directly decrypting the watermarked ciphertext data. Experimental results have shown that the algorithm can efficiently detect different tampering operations while protecting data content security with OPES.