Multiple images encryption and authentication using cascaded phase encoding with random sparse constraint

In this paper, multiple–image encryption and authentication is proposed using cascaded phase encoding (CPE) with random sparse constraints. Instead of sparsely sampling the retrieved ciphertexts, every original image is encoded into two sparse phase-only masks directly using CPE with random sparse constraints in the encryption process of this scheme. Two ciphertexts and random sparse constraints are required for decryption and authentication, which enlarges the key space and enhances the security simultaneously. Additionally, the amount of data from the retrieved phase only masks for every image in a very small way, so this scheme can encode more images and the encryption capacity is enlarged greatly. Various simulation results are shown to demonstrate the feasibility and security of this proposal. (letter)