Secure image encryption technique based on multiple Fresnel diffraction transforms

In this paper, we propose a new secure image encryption algorithm based on the multiple Fresnel diffraction transforms (MFDTs). First, we discuss the properties of MFDTs in detail and conclude that the MFDTs are strongly affected by the diffraction distances. Next, we design a series of diffraction distances as the encryption keys to enhance the security of encryption algorithm. Numerical experiments show that the MFDTs depend strongly on the diffraction distances, the decryption can proceed when the all keys are correct, and the algorithm is robust to the attacks, such as JPEG lossy compressing, cropping, superposing noise, and resampling from the screen copy. Since there is no simple “one-to-one” relationship between the plain text and cipher text in the MFDTs, it is extremely difficult to decrypt the keys with the exhaust research method, the optical scanning method, and the known-plaintext phase retrieval algorithm. Therefore, the encryption algorithm has a higher level of security.