Dynamic Watermarking-Based Integrity Protection of Homomorphically Encrypted Databases - Application to Outsourced Genetic Data

In this paper, we propose a dynamic database crypto-watermarking scheme that enables a cloud service provider (CSP) to verify the integrity of encrypted databases outsourced by different users. This scheme takes advantage of the semantic security property most homomorphic cryptosystems have, so as to embed a watermark into encrypted data without altering users’ data. The incorrect detection of the watermark, not only informs the CSP the database has been illegally modified but also indicates which data have been altered. In addition, the proposed scheme is dynamic in the sense the watermarking and integrity verification processes can be conducted along the database lifecycle, i.e. even when the database owner updates his or her data (i.e. addition, suppression or modification of database elements). Experimental results carried out with the Paillier cryptosystem on a genetic database demonstrate that our method can efficiently detect different illegal data tamper with a high location precision.