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An information hiding method on escape sequences of Huffman coding which can embed a great deal of secret information into AAC files is proposed based on the research of AAC coding standard. The proposed algorithm first unpacks the cover AAC file to search for the escape sequences, and then modifies least significant bit (LSB) of the escape sequences with the approach of matrix encoding, to improve...
Compositing is one of the most common forms of digital image tampering. In this paper, we present a passive approach to detect composite JPEG images by measuring inconsistencies of blocking artifacts. Firstly, double-compression detection is performed to estimate the primary quality factor. Secondly, the blocking artifacts ratio mapping is extracted in the DCT domain via computing the blocking artifacts...
In this paper, a new efficient method of computing modified discrete cosine transform (MDCT) in MP3 audio coding is proposed. We first define a scaled discrete cosine transform (SDCT), then convert N-point MDCT to N/2-point SDCT. Next we factor N/2-point SDCT matrix mathematically. The factored SDCT matrices are used to develop a fast MDCT algorithm for realizing N-point MDCT. We show that the proposed...
Scalable Video Coding(SVC) provides flexible adaptation to bandwidth fluctuations and device capabilities. Thus to preserve such adaptation capabilities many layered access control emerge. In this paper, through analyzing and modeling the bitstream of SVC we transform the scalable bitstream into a hierarchical structure, based on which we propose a secure and efficient hierarchical access control...
We introduce the notion of obligation constraints in the context of access control systems. Such constraints requires that in order to have all permissions necessary to complete a sensitive task, the cooperation of at least a certain number of users is required. In this paper, we formally define the notion of obligation constraints, strict obligation constraints, and introduce the obligation satisfy...
Matrix embedding has been proved to be an important steganographic scheme that can improve the embedding efficiency. In this paper, we propose a novel matrix embedding scheme with improved embedding efficiency. The original optimal embedding problem was converted to a problem of finding an optimal solution for over-defined systems of equations. Walsh spectrum and fast Hadamard transform are used to...
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