Localization and security enhancement of block-based image authentication

Most block-based image authentication techniques that are presented in the literature sacrifice localization accuracy in order to resist vector quantization (VQ) counterfeiting attacks. In this paper, we show that strong cryptography schemes, which produce a long signature, can be used to sign image blocks without regard to the size of these blocks. In addition, a new approach to generate overlapped watermark segments for image blocks is presented. These watermarks are generated using one-way function based on an NP-complete problem. Moreover, a block-based image authentication technique is proposed. This technique provides strong protection against the VQ attack, as well as a great enhancement in localization accuracy and system security.