Partial Encryption of Images for Real-time Applications

Multimedia systems mostly base security on a restricted access to services. In the context of real-time imaging applications, this model suffers several drawbacks. Applications become vulnerable to password attacks and once exposed attackers have access to all the data. An alternative consists of the systematic encryption of all data. When dealing with images, this approach is inconvenient because the data needs to be processed in its entirety before users can gain any insight. As well, the decryption task requires large amounts of processing power. This presentation shows how partial encryption can match applications requirements without the overhead of full encryption. The paper first analyzes several schemes mixing encryption and image encoding. Then we focus on a technique that implements partial encryption of images based on JPEG. The technique is built to meet two major requirements: (1) preserve the overall bitrate, and (2) remain compliant with the JPEG file format. Finally we introduce and elaborate on a new scheme that combines flexibility, multiple encryption, spatial selectivity, self sufficiency, and format compliance. We show how it could fit the needs of real-time applications.