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 rst 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.