Secure hybrid robust watermarking resistant against tampering and copy-attack

A method for generating watermarked data z based on some original data x, wherein said robust watermark w contains multi-bit informative winf and reference wref watermarks encoded and embedded in such a way as to resist against attacks, and an authentication watermark wfrag contextually encoded, encrypted and embedded in orthogonal or almost orthogonal positions with respect to the robust watermark w, comprising the steps of:

• (a) encoding said multi-bit message b, possibly using any error correction code (ECC),
• (b) generating said w as a function of said key k and said message b encoded and/or encrypted as codeword c, where said w consists in a said informative watermark winf and said reference watermark wref,
• (c) generating said authentication watermark wfrag as a function of said key k and said contextual information,
• (d) embedding said robust watermark w into said original data x to get said robustly marked data y,
• (e) embedding said authentication watermark wfrag into said robustly marked data y in orthogonal manner to said informative watermark winf, resulting into the final marked data z
• whereby said reference watermark wref assists amongst others in the estimation and recovering from local and global geometrical image alterations, channel state estimation, verification of reliability, fast detection of the said robust watermark w presence in said z and synchronized decoding of said error correction codes (ECC), and said authentication watermark wfrag assists in tampering detection, authentication and prevention of estimation of robust watermark w or informative watermark winf with following copying to another target media known as the copy attack, and identification of the reliability of said informative watermark winf, and furthermore whereby said z is visually indistinguishable from said x.