| Summary: | 博士 === 亞洲大學 === 資訊工程學系 === 102 === With the advancement of the Internet and development of multimedia technology, multimedia data have been an ease to access and distribute from one place to another. Obviously, the multimedia data can be protected before and after transmission by multimedia encryption, but data security after decryption against illegal users are critical and urgent. Only combination of encryption and fingerprinting, generally known as joint fingerprinting and decryption (JFD), can provide both confidentially and proper usages suitable for multimedia content protection.
Inspired by the conventional JFD framework, where the encryption process is performed at the sender side before transmission, and the fingerprint embedding and decryption processes are performed at the receiver side simultaneously, this dissertation presents the JFD scheme adopting three new different approaches, namely, the joint fingerprinting and decryption for vector quantization in resistance to noise, a reversible joint fingerprinting and decryption for vector quantization images, and a sub-pixel encryption and sub–block decryption-based fingerprinting scheme. The first scheme is made up from two encryption techniques, which encrypt a host image on the sender side. The first technique uses static key-trees and while the second adopts dynamic key-trees, a simplified version of the first technique. In decryption phase, when the subscriber receives the encrypted images, these images are jointly decrypted and fingerprinted and are slightly different from the original images. The experimental results show that the encrypted image is unintelligible, and the recovered image has desirable image quality resistant to noise interference.
Another JFD scheme, that is the extension of previous idea, includes reversibility mechanism developing from side match vector quantization(SMVQ). With reversibility property of SMVQ, the proposed scheme can extract the fingerprint without referring to the original image; that is, the fingerprinted copy can be completely recovered to the un-fingerprinted version. The experimental results show that the proposed scheme can achieve high perceptual security (with PSNR below 12 on average), high fingerprinted visual quality (with PSNR above 28 on average), and desirable fingerprint payload (about 0.6 bit/per block).
A low complexity joint fingerprint and decryption (JFD) scheme based on exclusive-or operations has been proposed. The scheme encrypts only sub-pixels of the entire image using a tiny lookup table generated by a stream cipher. In the decryption process, some pixels can be completely recovered and the fingerprinting process depends on four different directions of sub-image blocks. The method successfully leaves the user’s fingerprint during decryption and produces slightly different media copies. The experimental results show that the proposed scheme is highly effective in terms of perceptual security and fingerprinted visual quality.
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