APPARATUS AND ITS METHOD OF QUANTIZATION-BASED WATERMARKING WITH IMPROVED SECURITY

摘要

A quantization-based watermark insertion apparatus for improving security, a method therefor, a watermark authentication apparatus, and a method therefor are provided to be strong in an image fabrication and a vector quantization attack by statistical analysis by enhancing inter-block independency and reducing a statistical characteristic by block random mapping, quantization value adjustment, and dithering. A random mapping unit(110) divides an image received from the outside into a plurality of blocks by a secret key, shuffles the order of the blocks, and arranges the shuffled blocks as a block for inserting a watermark. A watermark inserting unit(120) inserts the watermark into the block arranged in the random mapping unit(110) according to an SVD(Singular Value Decomposition) value by using a previously defined quantization value. A correction unit(130) corrects a quantization error generated in an image into which the watermark is inserted in the watermark inserting unit(120). A dithering unit(140) performs dithering for the image corrected in the correction unit(130), and removes a statistical characteristic. An inverse mapping/correcting unit(150) executes correction to correct an error generated by the dithering performed in the dithering unit(140), and outputs an image into which the watermark is inserted through an inverse SVD process. An encryption unit(160) encrypts the secret key used in the random mapping of the random mapping unit(110) and an image feature used in the dithering of the dithering unit(140) by using a public key, and outputs the encrypted value.