ROBUST HIDDEN DATA EXTRACTION METHOD FOR SCALING ATTACKS

摘要

A product and process for extracting hidden data (2) from a stego-image (10') that has been subjected to scaling attacks are disclosed. The hidden data extraction method of the present invention retains the one-to-one mapping of the stego-image blocks to the corresponding blocks (18) in the scaled image. When the stego-image (10) is scaled down, the block size for extracting the hidden data (2) is reduced proportionally. When the stego-image (10) is scaled up, the block size for extracting the hidden data (2) is increased proportionally. The total overall number of blocks of pixels (18) to be examined is kept constant between the scaled image (10') and the stego-image (10). The hidden data extraction method can be combined with any existing block-DCT based data hiding method to provide an overall method for dealing with scaling attacks. Both the extraction method and the combined method can be implemented in software and stored within a machine-readable medium.