Wavelet Domain Image Encryption by Subband Selection and Data Bit Slelection

Widespread popularity of wireless data communication devices, coupled with the availability of higher bandwidths, has led to an increased user demand for content-rich media such as images and videos. Since such content often tends to be either private, sensitive, or paid for, there exists a requirement for securing such communication. However, solutions that rely only on traditional compute-intensive security mechanisms are unsuitable for resourceconstrained wireless devices. In this paper, we propose a selective partial image encryption scheme, which enables a trade-off between the effectiveness of the encryption method and the cost of using the method. The encryption scheme is invoked during the image compression process, with the encryption being performed between the quantizer and the entropy coder stages. Three data selection schemes have been used as part of the partial encryption scheme: subband selection, data bit selection, and random selection of pixel data. The experimental results for over 500 test images reveals that the fraction of data to be encrypted with our scheme is between 1/4,096 and 1/256 and the PSNRs are between about 9.5dB to 7.5dB. Since the encryption cost is very low and the effectiveness is good, the proposed scheme can potentially be used to provide secure communications in a variety of wired/wireless scenarios.