Single-channel color image encryption based on asymmetric cryptosystem

A single-channel color image encryption is proposed based on asymmetric cryptosystem. The color components respectively multiplied with three random phase encryption keys are first combined into one gray image using convolution for further encoding into a real-value gray ciphertext with the asymmetric cryptosystem. Then four decryption keys, which are different from encryption keys and generated in the encryption process, can be used for image decryption. As a result, a more compact and robust system, permitting a real-value gray ciphertext to be transmitted, has been obtained. The feasibility and effectiveness of the proposed method are demonstrated by numerical results.