Access Control Mechanism for Blog Posts with Fine- Grained Ability Using Simple Operations

Access control enables the owners to assign different users different permissions to see different views. The current blog system does not support fine-grained authorization. That is, the bloggers disallow to just assign partial contents of the blog posts （i.e., a paragraph or several paragraphs） to readers. The management cost is no doubt to be significantly increased while handling the authorizations on the huge amount of blog articles. In this paper, we propose a scheme for supporting a fine-grained access control mechanism on blog articles. The advantage is that bloggers are able to authorize partial contents of blog posts to different users or groups of users.

Efficient Certificateless Aggregate Signature Scheme

In ubiquitous computing, data should be able to be accessed from any location, and the correctness of data becomes vital during the communication. Suppose that many users sign different messages respectively, before forwarding or sending these messages, then the verifier must spend a lot of computing time to verify their signatures. Consequently, the aggregate signature scheme is an effective method of improving efficiency in this kind of systems, which provides the convenience for the verifier. In this paper, we propose a new certificateless aggregate signature scheme which is efficient in generating a signature and verification. This scheme is provably secure under the extended computational Diffie-Hellman assumption.

Double-Layer Data Embedding Scheme Based on Three-Pixel Differences

Steganography is a technique to hide the secret data into digital media without getting any unexpected notices. The traditional steganographic method, namely least significant bit （LSB） replacement, is a simple but insecure scheme. To overcome the traditional drawbacks, this paper proposes a steganographic scheme, which is called double-layer hiding method. The experimental results confirm that the proposed scheme achieves better biding capacity with high ability of resisting security analysis.

Dual Image Reversible Data Hiding by Modifying Least Significant-Bit Matching Revisited Rules

The concept of dual image reversible data hiding（DIRDH） is the technique that can produce two camouflage images after embedding secret data into one original image.Moreover,not only can the secret data be extracted from two camouflage images but also the original image can be recovered.To achieve high image quality,Lu et al.＇s method applied least-significant-bit（LSB） matching revisited to DIRDH.In order to further improve the image quality,the proposed method modifies LSB matching revisited rules and applies them to DIRDH.According to the experimental results,the image quality of the proposed method is better than that of Lu et al.＇s method.

An Adaptive Steganographic Algorithm for Point Geometry Based on Nearest Neighbors Search

In this study, we extend our previous adaptive steganographic algorithm to support point geometry. For the purpose of the vertex decimation process presented in the previous work, the neighboring information between points is necessary. Therefore, a nearest neighbors search scheme, considering the local complexity of the processing point, is used to determinate the neighbors for each point in a point geometry. With the constructed virtual connectivity, the secret message can be embedded successfully after the vertex decimation and data embedding processes. The experimental results show that the proposed algorithm can preserve the advantages of previous work, including higher estimation accuracy, high embedding capacity, acceptable model distortion, and robustness against similarity transformation attacks. Most importantly, this work is the first 3D steganographic algorithm for point geometry with adaptation.

Guest Editorial Special Issue on Information Security and Applications

With the growing of digitized data transforming on Internet,the issues of information security,data privacy,and forensic analysis have become more and more attracted.Researchers have provided solutions for problems in the field.The objective of this special issue is to present research and development activities in the various aspects.After a very careful review,

An Image Authentication Method by Grouping Most Significant Bits

In 2011, Chan proposed an image authentication method by producing the parity check bits from pixels whose bits have been rearranged. Due to this rearrangement, the value of the most-significant bit of each tampered pixel can be determined according to its parity check bits. With the help of the most-significant bit of the pixel, the pixel can be recovered by selecting two possible （7, 4） Hamming code words. However, if the distance between two Hamming code words is within a certain range, incorrect selection may occur. Chan＇s method added one additional bit to indicate the correct one. It is trivial that this may degrade the quality of the authenticated image. In this paper, we group four most-significant bits into different groups to form a mapping codebook and the mapping codebook is used to produce authentication data instead of the （7, 4） Hamming code book. The experimental results show that the proposed method has a greater ability to recover tampered areas.