An Authenticating Algorithm with Multi-compression Compatible in DCT Domain

If the user can compress the multimedia repeatedly, it will decrease the numbers of different resolution copies largely, and then reduce the transmission volume. Combining tamper-detection with DCT-based multi-compression will bring great benefit to the owner in copyright protection system. By embedding the information into the maximal quantized DCT coefficient, the user may make compression with the production in some distance, and finally the integrity of the content will be authenticated. An authenticating algorithm with multi-compression compatible is presented in this paper. The experiment shows that this semi-fragile watermarking algorithm can meet the need of multi-compress, permit the authentication pass, detect the malicious tamper, and obtain better imperceptibly as well as robustness.