ABSTRACT
Generally, perceptual encryption is realized by encrypting some sensitive parameters. Thus, it belongs to the category partial encryption. There are two core issues in perceptual encryption. The first is how to partition media data into sensitive parameters. Here, the significance denotes the sensitivity to human perception. The second issue is how to select the sensitive parameters according to security or quality requirements. There are some means [1-7] to accomplish this. Suppose there are N parameters in media data P, and the parameters are ordered from the least significant to the most significant that is, p0, p1, …, pN-1. Let the quality factor Q range from 0 to 100, with the higher value for Q denoting better quality. Then the number of parameters that will be encrypted is determined by
n Q N= -
( ) ,
100 100
where x denotes the highest number no larger than x. Additionally, the n parameters are selected from the order 0 to n, as shown in Figure 7.1. Thus, the second issue can be solved.
