Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2019-01-28 Cooperative journals: 《计算机应用研究》
Abstract： For the problem of the singular value decomposition (SVD) watermarking algorithm caused high false alarm rate and low robustness, this paper proposed an adaptive zero watermarking algorithm , which was based on block NMF and boost normed singular value decomposition. First, the original gray image was transformed into two levels of DWT transform, then after the transformation of the LL2 subbands were divided into non-overlapping blocks, and each sub-block was broken down into NMF with rank r, then boost normed singular value decomposition was used for eigenmatrix derived from NMF decomposition. According to the relationship between the maximum singular value of each block matrix and the mean value of the global maximum singular value, it constructed feature-vector . Finally the generated feature vector was xor operation with the random encrypted watermark image of Arnold and the logistic map to generate a zero watermark. The parameter β in the singular value matrix must be determined adaptively by the optimization algorithm (BAS) , and find out the scaling ratio of the most resistant attack. The experimental results show that, in the false alarm problem, the NC value is below 0.4. Under the condition of JPEG compression, noise, filtering, rotation, shearing and mixed attack, the normalized coefficient NC of the extracted watermark image and the original watermark image can reach more than 99%. The method can solve the false positive errors efficiently and has strong robustness. Can resist all kinds of attacks effectively.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-05-18 Cooperative journals: 《计算机应用研究》
Abstract： The certificateless signcryption scheme effectively solved the key escrow problem in identity based signcryption scheme while kept its certificate-free property. Aiming at the low computation efficiency and poor security of the existing certificateless signcryption scheme, this paper proposed a new certificateless signcryption scheme without pairings based on a sort of secure signature scheme. The scheme used binding the hash functions with identities of users and the method of combing the public and private key to generate a new key. The scheme was confidential and unforgeable based on the hard problem of discrete爈ogarithm on the elliptic curve under the random oracle model. Compared爓ith爀xisting爏chemes, the proposed爉ethod爄mproves爐he爀fficiency without爑sing燽ilinear爌airing燼nd爀xponential爋peration爑nder爐he爏ecure爏ituation.
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