Enhanced security computational double random phase encryption by using additional random function

Image encryption technique has been actively researched and improved. Double Random Phase Encryption (DRPE), known as the typical way of optical encryption, can easily encrypt images. In the decryption process of DRPE, the complex conjugate of random phase mask used as the encryption key in the Fourier domain is used as the decryption key. As a result, computational DRPE has a vulnerability in image transmission when the random phase mask is stolen. Our proposed method utilizes the random function defined by the sender, and it generates additional random variable to multiply the random phase mask. Finally, our proposed method can enhance the security of the encryption process. However, the random phase mask and random variable information generated by random function are needed to decrypt the image. To send both information, high cost is required in the transmission process. To overcome this problem, our proposed method sends the conjugate random phase mask and random function to the receiver for the decryption process. Finally, our proposed method can enhance security with a low transmission cost.