A tunable selective encryption scheme for H.264/AVC

In this paper a tunable selective encryption scheme for H.264/AVC is proposed to provide a tunable scrambling effect. The user can adjust the scrambling effect according to specifications of the application. Three kinds of syntax element are chosen to be encrypted: intra prediction modes, the sign bits of nonzero quantized DCT coefficients and the sign bits of motion vectors. The tunable feature is achieved by controlling the number of each kind of syntax element to be encrypted. To simplify the implementation and save the computational cost, a simple control mechanism is proposed to adjust the control factors. Experimental results show that the scrambling effect can be effectively adjusted with no or very minimal impact on the compression performance. The proposed scheme is secure against the replacement attack and the slight computational cost can meet real-time processing.