A Novel Back Propagated Image Encryption Method with PGP Public Key and 1D Logical Map

From the past to the present, encrypted communication has played a crucial role in protecting the confidentiality of government-level information, military information, and personal information. Numerous methods have been developed to encrypt the sent message and ensure that only the recipient can decrypt it. New encryption methods are still being developed today. While in the past, the message requiring encryption was primarily text-based, multimedia products such as images and videos have emerged, necessitating encryption to protect personal data and the confidentiality of government or institutional information. What distinguishes multimedia messages from text-based messages is the similarity of pixels in digital images and the large size of their information. This high data density and similar data make encryption difficult. In this case, traditional text encryption methods are inadequate. The image encryption method proposed in this study differs from traditional text encryption methods in terms of its methodology. The study consists of three steps. In the first stage, the rows and columns in the plain image are shifting using the classic Affine encryption algorithm. In this stage, the width and height values ​​of the image are used to generate the Affine key. In the second step, the recipient's pretty good privacy (PGP) key is obtained. The resulting PGP key generates the key sequence , which will be used in the encryption process. Simultaneously, the values ​​obtained from the PGP key are used to obtain the value, the input parameter of the 1D logistic map, and the initial value . In the third step, a back propagated XOR operation is applied to the image using the data obtained from the 1D logistic map, encrypting all pixels in the plain image. Experiments were conducted on grayscale and RGB images of different sizes in the proposed study. The NPCR value of 99.6078 and UACI value of 33.5323, respectively, demonstrate the feasibility of the proposed method.