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Abstract: In this paper, we propose a steganographic scheme based on the varieties of coefficients of discrete cosine transformation of an image. The major problem of hiding data in the high-frequency coefficients of discrete cosine transformation is that rounding errors will be added into the spatial-domain image, and thus cannot be transformed back to the correct modified coefficients of the discrete cosine transformation. To solve this problem, we use integer mapping to implement our discrete cosine transformation. Thus, the image recovered from the modified coefficients can be transformed again to the correct data hidden coefficients. [Copyright &y& Elsevier]

Abstract: In this paper, we present a new and effective color image retrieval scheme for combining all the three i.e. color, texture and shape information, which achieved higher retrieval efficiency. Firstly, the image is predetermined by using fast color quantization algorithm with clusters merging, and then a small number of dominant colors and their percentages can be obtained. Secondly, the spatial texture features are extracted using a steerable filter decomposition, which offers an efficient and flexible approximation of early processing in the human visual system. Thirdly, the pseudo-Zernike moments of an image are used for shape descriptor, which have better features representation capabilities and are more robust to noise than other moment representations. Finally, the combination of the color, texture and shape features provide a robust feature set for image retrieval. Experimental results show that the proposed color image retrieval is more accurate and efficient in retrieving the user-interested images. [ABSTRACT FROM AUTHOR]

Abstract: Typical wireless sensor network comprises sensors and a sink. The sink gathers and analyzes the data from sensors and then takes the corresponding action. Such architecture may have single-point of failure problem. Besides, when sensors have no direct link with the sink, they must deliver data by hopping scheme. The sink may take a longer time to collect data. Furthermore, faulty sensors and environment interference may cause an incorrect result. To overcome the mentioned problems, we propose a consensus problem based solution to make all sensors reach an agreement without the sink. It can conduct actions more quickly and directly. [Copyright &y& Elsevier]

Abstract: Data hiding, as the term itself suggests, means the hiding of secret data in a cover image. The result is a so-called stego-image. Reversible data hiding is technique, where not only the secret data can be extracted from the stego-image, but the cover image can be completely rebuilt after the extraction of secret data. Therefore, reversible data hiding is the choice in cases of secret data hiding, where the recovery of the cover image is required. In this paper, we propose a high-capacity reversible data hiding scheme based on pattern substitution. Our scheme gathers statistical data concerning the occurrence frequencies of various patterns and quantifies the occurrence frequency as it differs from pattern to pattern. In this way, some pattern exchange relationships can be established, and pattern substitution can thus be used for data hiding. In the extraction stage, we reverse these patterns to their original forms and rebuild an undistorted cover image. Our experimental results demonstrate the practicability of the proposed method. In fact, our new scheme gives a better performance than pair-wise logical computation (PWLC) in terms of both hiding capacity and stego-image visual quality. [Copyright &y& Elsevier]

Abstract: Recently Das et al. proposed a novel remote user authentication scheme using bilinear pairings. Chou et al. identified a weakness in Das et al.''s scheme and made an improvement. In this paper, we show that both Das et al.''s and Chou et al.''s schemes are insecure against forgery and replay attacks. We proposed an improved scheme that overcomes the security flaws without affecting the merits of the original scheme. [Copyright &y& Elsevier]

Abstract: A verifiable image secret sharing scheme, which is based on the Thien-Lin scheme and the intractability of the discrete logarithm, is proposed in this paper. The new scheme can identify the cheaters no matter if she/he is the original secret image holder or the participant; because each participant chooses her/his own secret shadow by her/himself, the new system doesn''t need a security channel; Due to the same fact, the secret shadow of each participant can be reused. In addition, the size of each shadow image, same as the Thien-Lin scheme, is smaller than that of the original secret image. [Copyright &y& Elsevier]

Abstract: Proxy signature, where the original signer can delegate his signing authority to the proxy signer, is frequently applied to many applications, such as the mobile agents system, electronic-vote etc. In these practical circumstances, as the signing ability of the proxy signer may be abused, we introduce the multiple-times proxy signature scheme, which restricts the signing ability of the proxy signer. The proposed scheme can restrict the attacker''s forgery and the abuse of the proxy signer, and release the overhead of revocation. Finally, we support our scheme with detailed security and performance analysis. [Copyright &y& Elsevier]

Abstract: Since the number of server providing the facilities for the user is usually more than one, the authentication protocols for multi-server environment are required for practical applications. Most of password authentication schemes for multi-server environment are based on static ID, so the adversary can use this information to trace and identify the user''s requests. It is unfavorable to be applied to special applications, such as e-commerce. In this paper, we develop a secure dynamic ID based remote user authentication scheme to achieve user''s anonymity. The proposed scheme only uses hashing functions to implement a robust authentication scheme for the multi-server environment. It provides a secure method to update password without the help of third trusted party. The proposed scheme does not only satisfy all requirements for multi-server environment but also achieve efficient computation. Besides, our scheme provides complete functionality to suit with the real applications. [Copyright &y& Elsevier]

Abstract: Many identity based signcryption schemes have been proposed so far. However, all the schemes were proven secure in the random oracle model which has received a lot of criticism that the proofs in the random oracle model are not proofs. In this paper, motivated by Waters'' identity based encryption scheme, we propose the first identity based signcryption scheme without random oracles. We prove that the proposed scheme is secure in the standard model. Specifically, we prove its semantic security under the hardness of Decisional Bilinear Diffie–Hellman problem and its unforgeability under the Computational Diffie–Hellman assumption. [Copyright &y& Elsevier]

Abstract: With the great convenience of computer graphics and digital imaging, it becomes much easier to alter the content of images than before without any visually traces to catch these manipulations, i.e., many fake images are produced whose content is feigned. Thus, the images can not be judged whether they are real or not visually. In order to detect fake images, this paper proposes a detection scheme, which, firstly, uses watermarks to locate the alteration, and then, uses support vector machine (SVM) as a classifier to make a binary decision on whether an image is fake or real. The experimental results also demonstrated the effectiveness of the proposed scheme. [Copyright &y& Elsevier]

Abstract: In 2004, C.-C. Yang, T.-Y. Chang and M.-S. Hwang proposed an efficient multi-secret sharing scheme based on two-variable one-way function and Shamir''s secret sharing. In order to add the verifiable property into previous scheme, J. Shao and Z. Cao proposed an efficient (t,n) verifiable multi-secret sharing based on YCH [C.-C. Yang, T.-Y. Chang, M.-S. Hwang, A (t,n) multi-secret sharing scheme, Applied Mathematics and Computation 151 (2004) pp. 483–490.] in 2005. Both of the previous schemes need a secure channel. This paper presents a verifiable multi-secret sharing based on YCH, intractability of Discrete Logarithm (DL) and RSA cryptosystem. In our scheme each participant chooses her/his shadow by her/himself and there is not any need to a secure channel. In addition, compared with Shao and Cao scheme, verifiable property is more efficient in our scheme. [Copyright &y& Elsevier]

Abstract: A novel oblivious color image watermarking scheme based on Linear Discriminant Analysis (LDA) is proposed in this paper. The watermark accompanied with a reference is embedded into the RGB channels of color images. By applying the embedded reference watermark, a linear discriminant matrix is obtained. The watermark can be correctly extracted under several different attacks. Experimental results show that the proposed scheme has good performance against several attacks. Especially when the watermarked image is enhanced in luminance and contrast at a rate of 50%, the proposed method can extract the watermark with few bit errors. [Copyright &y& Elsevier]

Abstract: In 1996, Jakobsson et al. proposed a designated verifier signature scheme in which only one specified person, called a designated verifier, can be convinced of the validity of the signature and the identity of the signer. This is possible by giving the designated verifier the ability to simulate a signature him/herself in an indistinguishable way. Therefore, the other third party cannot determine whether the signature is from the signer or the designated verifier. However, in some circumstances, the third party may be convinced that a signature intended for the designated verifier is actually generated by the signer. In 2003, Saeednia et al. proposed a strong designated verifier signature scheme to overcome this problem. However, we found that Saeednia et al.''s scheme would reveal the identity of the signer if the secret key of this signer is compromised. In this paper, we provide a new strong designated verifier signature scheme that provides signer ambiguity, even if the secret key of the signer is compromised. We also analyze the proposed scheme. [Copyright &y& Elsevier]

Abstract: Recently, Chang et al. proposed an ID-based multisignature scheme based on RSA without reblocking and predetermined signing order. The scheme simplifies the public key certification process and overcomes the moduli clashes problem. In this paper, we show that the scheme is insecure against several forgery attacks. [Copyright &y& Elsevier]