A Low-Overhead Secure Image Compression over Wireless Multimedia Sensor Network

Due to inherent limitations in processing power, storage, and bandwidth, multimedia data processing is a challenge in wireless multimedia sensor network (WMSN). Protection of such data from unauthorized access is also of utmost importance. In this work we propose a lightweight image encryption scheme which works on compressed image captured by WMSN. It works in two steps. In the first step, the key is generated by picking a macroblock (key macroblock) dynamically from a template which is prepared by a set of video frames offline. This dynamic selection of key macroblock is done using a proposed address mapping mechanism. In the second step, each macroblock from compressed input image is encrypted by performing exclusive OR between the generated key and the intensities of the key macroblock. Performance of the scheme is evaluated through simulation in Cooja, the Contiki network simulator to make it readily implementable in real life mote e.g. MICAz. Performance is compared and the results show that the proposed securing scheme saves on an average 49% energy over its competitors while maintaining acceptable reconstruction quality. Finally, security analyses are carried out to prove system efficiency through histogram analysis, key sensitivity and key-space analyses. System robustness against noise and occlusion attacks has also been proved.