High Security Multiple-image Encryption using Discrete Cosine Transform and Discrete Multiple-Parameter Fractional Fourier Transform

—A multiple-image encryption scheme is proposed by using discrete cosine transform and discrete multiple-parameter fractional Fourier transform (DMPFRFT). Each image is performed by discrete cosine transform and filtering procedure and then multiplexed into a complex signal. After operated by a pixel scrambling, the complex signal is multiplied by random phase mask, and then encrypted into one image in DMPFRFT domain. The original images can be retrieved by using such correct keys as pixel scrambling operation, random phase mask and the parameters of DMPFRFT. Numerical simulations have been done to verify the feasibility and security of the proposed method