A multimedia communication system enables multimedia data's generation, storage, management, distribution, receiving, consuming, editing, sharing, and so on. In such systems, there are various security issues, which must be considered such as eavesdropping, intrusion, forgery, piracy and privacy, etc. Until now, various security solutions for multimedia communication systems have been reported, while few works have surveyed the latest research advances. This paper gives a thorough review to multimedia information system security. It introduces a general architecture of multimedia information system, and investigates some security issues in multimedia information systems. It reviews the latest security solutions such as Digital Rights Management (DRM), confidentiality protection, ownership protection, traitor tracing, secure multimedia distribution based on watermarking, forgery detection, copy detection, privacy-preserving data mining, secure user interface, intrusion detection and prevention. Moreover, the paper presents some hot research topics such as Trusted Computing, steganography, security in network or service convergence, security of content sharing in social networks, privacy-preserving data processing, multimedia forensics and intelligent surveillance in multimedia information system security. It is expected to benefit readers by providing the latest research progress, advising some research directions and giving a list of references about multimedia system security. Povzetek: Prispevek podaja pregled novejših pristopov pri zagotavljanju varnosti multimedijskih informacijskih sistemov.

Encryption is used to securely transmit data in open networks. Each type of data has its own features; therefore different techniques should be used to protect confidential image data from unauthorized access. In this paper we propose a novel concept of combined partial image encryption using phase manipulation and sign encryption. Entire encryption process involves two stages where image to be encrypted are applied to phase manipulation block. In first stage Fourier Transform (FT) is applied to get phase and magnitude of the input image. Phase of the image are scrambled to get modified image after applying Inverse Fourier Transform. In second stage the modified image is partially encrypted by using sign encryption. Sign Encryption finally gives resultant partially encrypted image by extracting the sign bits of modified image. Experiment is conducted for an image using MATLAB software. From the experiment we obtained partially encrypted image at the end of encryption process. Decryption process employs exactly reverse process of encryption which results in the reconstructed images.

Abstract: Wireless sensor networks are increasingly gaining attention. In recent years, a great deal of monitoring, control and tracking applications have been designed for different scenarios. For such networks, camera-enabled sensors can retrieve visual data from a monitored field, providing valuable information for many applications. In general, those networks have resource constraints of processing, memory, energy and transmission bandwidth, imposing many design challenges. Nevertheless, a group of applications may also have security requirements, which bring additional complexity to be handled. Most traditional security mechanisms for popular networks, like the Internet, are not suitable for wireless sensor networks, demanding proper investigation in this area. In this paper, we survey recent developments in encryption and privacy in wireless sensor networks deployed for transmissions of image snapshots, reviewing innovative approaches to provide different levels of security. Promising research directions are also discussed.