A wavelet-based public key image authentication watermarking

We introduce a new wavelet-based image authentication approach that the proposed approach can detect attacks on an authenticated image and indicate the modification area. The proposed authentication procedure first applies the image into a 3-level wavelet transform and the fingerprint of each subimage's block is then encrypted by a cryptosystem to replace the LSB of the block. The block's fingerprint is obtained by calculating the hash value of the block, its neighboring blocks, and its coarse approximation in low-pass subimage. The verification step only requires the user's public key to check whether the new calculated fingerprint is consistent with the decryption result of the LSB. Experimental results show that the proposed approach detects attacks including spatial or wavelet coefficients replacement efficiently, whereas the modification area is clearly indicated.