Image authentication and encryption algorithm based on RSA cryptosystem and chaotic maps

In the era of today’s open network communication, security issues of private data over these networks are at their peak, and it is challenging to secure data transmission. Therefore, to overcome these security crises, cryptographers need to develop efficient and robust encryption algorithms. This article proposes a new multilayer image ciphering scheme along with a modified authentication technique for grayscale and color images by using the RSA public key cryptosystem and two chaotic maps. The chaotic key sequences generated through a 2D piecewise smooth non-linear chaotic map (2D-PSNCM) are utilized to perform permutation of rows and columns to enhance the level of confusion. Also, bitwise XOR is applied to fulfill an intricate level of diffusion. To decrease the correlation and to strengthen the security level, the scrambling of pixels is created by using a suitable number of iterations of the Baker map. For authenticity purposes, the modified digital signature is proposed by using the RSA public key cryptosystem for partially encrypted images. The proposed digital signature is employed for further encryption purposes as well. The scheme provides multilayer security and is well-protected against different brute-force attacks. The secret keys and their arrangement in each layer of encryption are imperative for the correct decryption. The proposed algorithm’s robustness and efficiency are verified using multiple RGB and grayscale images. Security analysis demonstrates the validation by comparing it with some recent cryptographic image encryption algorithms. These results show the proposed algorithm’s robustness, such as vast sizeable keyspace, very low correlation coefficient, high sensitivity for keys, and good information entropy. Altogether, this proves the high efficiency of the proposed algorithm in resisting statistical attacks.