Optical color image encryption using position multiplexing technique based on phase truncation operation

•We propose a color image encryption based on the PTFT and the position multiplexing.•The proposed method maintains the nonlinear properties of encryption structure.•The proposed method can avoid the iterative attack.•The proposed method encrypts in only one spatial channel at a time.•Numerical results verify the high security and robustness of the proposed method.

We propose an optical color image cryptosystem based on position multiplexing technique and phase truncation operation. Compared with the reported color image encryption method, we employ the position multiplexing technique to encrypt the color image in only one spatial channel. Meanwhile, our proposed method can maintain the nonlinear characteristic of the cryptosystem and avoid various types of the currently existing attacks, especially the iterative attack. Simulation results are presented to demonstrate the security and robustness performance of the proposed method.