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Image hash functions find extensive applications in content authentication, database search, and watermarking. This paper develops a novel algorithm for generating an image hash based on Fourier transform features and controlled randomization. We formulate the robustness of image hashing as a hypothesis testing problem and evaluate the performance under(More)
This paper introduces a new framework for confidentiality preserving rank-ordered search and retrieval over large document collections. The proposed framework not only protects document/query confidentiality against an outside intruder, but also prevents an untrusted data center from learning information about the query and the document collection. We(More)
This paper addresses the access control issues unique to multimedia, by using a joint signal processing and cryptographic approach to multimedia encryption. Based on three atomic encryption primitives, we present a systematic study on how to strategically integrate different atomic operations to build a video encryption system. We also propose a set of(More)
A cooperative communication system explores a new dimension of diversity in wireless communications to combat the unfriendly wireless environment. While this emerging technology is promising in improving communication quality, some security problems inherent to cooperative relay also arise. This paper investigates the security issues in cooperative(More)
In secure group communications, the time cost associated with key updates in the events of member join and departure is an important aspect of quality of service, especially in large groups with highly dynamic membership. To achieve better time efficiency, we propose a join-exit-tree (JET) key management framework. First, a special key tree topology with(More)
An image hash is a randomized compact representation of image content and finds applications in image authentication, image and video watermarking, and image similarity comparison. Usually, an image-hashing scheme is required to be robust and secure, and the security issue is particularly important in applications, such as multimedia authentication,(More)
Sensor network has a great potential in applications such as habitat monitoring, wildlife tracking, building surveillance, and military combat. The design of a sensor network system involves several important issues, including the sensing coverage, node-to-node or node-to-base-station communications, and the security in information gathering and relay by(More)
! Desirable intermediate processing in multimedia transmission – Unequal error protection – Scalability by transcoding or scalable coding " heterogeneous environment: various bandwidth condition, computing capability, and power limit ! Quality, Time, and Value of multimedia – High quality version need to be protected with much bigger effort – Commercial(More)
In this paper, we propose a time-efficient contributory key agreement framework for secure communications in dynamic groups. The proposed scheme employs a special jointree/exit-tree topology in the logical key tree and effectively exploits the efficiency of amortized operations. We derive the optimal parameters and design an activation algorithm for the(More)