Computationally efficient selective video encryption with chaos based block cipher

Selective encryption techniques are usually used with resource limited communication infrastructure and devices like wireless networks and mobile devices, to reduce computational burden in securing large video data. This technique of securing a subset of data and hence reducing computation is usually considered a compromise on security. Similarly, if the data is not properly selected then the encryption procedure will result in compression inefficiency and format non-compliance. In this research work, these requirements of reduced computation with increased security, format compliance and compression efficiency are addressed. The security issue is addressed by carefully selecting the substitution boxes for the block cipher in use. For compression efficiency and compliance to the format the video data is selected such that the statistical and structural characteristics are preserved. In order to increase the security, different chaotic based substitution boxes, that are an integral part and the only nonlinear operation of the block ciphers, were studied for cryptographic strengths. The selected substitution boxes were used for permutation of selected video data and its encryption by integrating the S-box with the Advanced Encryption Standard and H.264/AVC. The video data selected to be secured, consist of discrete cosine transform coefficients; signs of trailing ones and non-zero transform coefficients. The discrete cosine transform coefficients were permuted using the selected S-box while the signs of trailing ones and non-zero transform coefficients were fully encrypted using AES with the modified S-box. Simulation results showed considerable visual degradation in the decoded video. It is also shown that the compression efficiency and format compliance was not compromised while keeping the computational load at minimum.