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Li B.,Shenzhen University | Li B.,Shenzhen Key Laboratory of Advanced Communications and Information Processing | Tan S.,Shenzhen University | Wang M.,Shenzhen University | And 2 more authors.
IEEE Transactions on Information Forensics and Security | Year: 2014

Relating the embedding cost in a distortion function to statistical detectability is an open vital problem in modern steganography. In this paper, we take one step forward by formulating the process of cost assignment into two phases: 1) determining a priority profile and 2) specifying a cost-value distribution. We analytically show that the cost-value distribution determines the change rate of cover elements. Furthermore, when the cost-values are specified to follow a uniform distribution, the change rate has a linear relation with the payload, which is a rare property for content-adaptive steganography. In addition, we propose some rules for ranking the priority profile for spatial images. Following such rules, we propose a five-step cost assignment scheme. Previous steganographic schemes, such as HUGO, WOW, S-UNIWARD, and MG, can be integrated into our scheme. Experimental results demonstrate that the proposed scheme is capable of better resisting steganalysis equipped with high-dimensional rich model features. © 2014 IEEE. Source


Liu H.,Shenzhen University | Liu H.,Shenzhen Key Laboratory of Advanced Communications and Information Processing | Cao W.,Shenzhen University | Cao W.,Shenzhen Key Laboratory of Advanced Communications and Information Processing
Chinese Journal of Electronics | Year: 2014

Cloud storage can provide flexible and sealable data storage services to users. However, once data is uploaded to the cloud without a copy in local computers, the user loses control of the data physically. So, it is necessary to study a method to ensure users' data integrity. Avoiding retrieving enormous storage data or checking the data by users, a proof of storage protocol with public auditing was proposed based on the lattice cryptography. The user computed the signatures of the blocks, and outsourced them to cloud servers. Cloud service providers combined the blocks. Third party auditor verified all blocks' integrity only through the combined message and signature. Based on the Small integer solution assumption, the presented protocol is secure against the lost attack and tamper attack from cloud service providers. Based on the Learning with error assumption, the presented protocol is secure against the curiosity attack from third party auditor. The protocol is quite efficient, requiring just a few matrix-vector multiplications and samplings from discrete Gaussians. Source


Li B.,Shenzhen University | Li B.,Shenzhen Key Laboratory of Advanced Communications and Information Processing | Ng T.-T.,Institute for Infocomm Research | Li X.,Beijing Institute of Technology | And 4 more authors.
IEEE Transactions on Information Forensics and Security | Year: 2015

To identify whether an image has been JPEG compressed is an important issue in forensic practice. The state-of-the-art methods fail to identify high-quality compressed images, which are common on the Internet. In this paper, we provide a novel quantization noise-based solution to reveal the traces of JPEG compression. Based on the analysis of noises in multiple-cycle JPEG compression, we define a quantity called forward quantization noise. We analytically derive that a decompressed JPEG image has a lower variance of forward quantization noise than its uncompressed counterpart. With the conclusion, we develop a simple yet very effective detection algorithm to identify decompressed JPEG images. We show that our method outperforms the state-of-the-art methods by a large margin especially for high-quality compressed images through extensive experiments on various sources of images. We also demonstrate that the proposed method is robust to small image size and chroma subsampling. The proposed algorithm can be applied in some practical applications, such as Internet image classification and forgery detection. © 2014 IEEE. Source


Xie N.,Shenzhen University | Xie N.,Shenzhen Key Laboratory of Advanced Communications and Information Processing | Zhang L.,Shenzhen University | Wu J.,Shenzhen University | And 2 more authors.
Wireless Personal Communications | Year: 2015

Though the binary exponential backoff (BEB) is a popular algorithm of collision avoidance in the IEEE 802.11 MAC protocol due to simple implementation, it causes the short-term unfair problem. Another popular algorithm is the history based adaptive backoff (HBAB), HBAB has better performance than conventional backoff algorithm by taking the channel states of past trials into account, where the length of its contention window (CW) is set artificially based on the prior knowledge of channel states. However, the length of CW in HBAB cannot be dynamically allocated and it often diverges from the optimal value. Therefore the application of HBAB will be limited in practical scenarios. In this paper, based on HBAB, we propose a new backoff algorithm which can control the length of CW according to the channel utilization ratio adaptively. The proposed algorithm is simple to implementation and can offer higher throughput and lower delay, compared with BEB and HBAB. Simulation results validate the superiority of the proposed algorithm. © 2015, Springer Science+Business Media New York. Source


Zhang L.,Shenzhen University | Xie N.,Shenzhen University | Xie N.,Shenzhen Key Laboratory of Advanced Communications and Information Processing | Wang H.,Shenzhen University | Wang H.,Shenzhen Key Laboratory of Advanced Communications and Information Processing
2015 IEEE International Conference on Ubiquitous Wireless Broadband, ICUWB 2015 | Year: 2015

In this paper, we consider the problem of direction of arrival (DOA) estimation achieved by a distributed way in wireless sensors networks. The goal for each node is to detect targets based on its local information and that of its neighbors through some iteration. Classic estimation methods, such as maximum likelihood (ML) algorithm, are not suitable here because there is often a requirement of a central unit to obtain the optimal solution. We propose a new distributed DOA estimation algorithms based on the randomized Gossip method, the goal of which is to realize the conventional Capon method by a distributed way. The proposed algorithm does not require any constraint on the network geometries, thereby making it suitable for distributed signal processing in large wireless sensor networks. The given simulation results illustrate the main characteristics of the proposed algorithm, including DOA resolution and mean square error (MSE) performance. © 2015 IEEE. Source

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