An image encryption method based on modified elliptic curve Diffie-Hellman key exchange protocol and Hill Cipher

Digital image protection is crucial since images often contain private and sensitive information in business, medical, and military. One of the best techniques for securing the content of these images is encryption. This article introduces a cryptosystem known as the elliptic curve Diffie-Hellman Hill Cipher (ECDHHC) that uses the modified eliptic curve Diffie-Hellman (ECDH) key exchange protocol to generate the shared secret key integrated with the Hill Cipher. An elliptic curve point-based secret shared key matrix using the ECDHHC, which will be used for encryption and decryption, is generated. Thereafter, the input image is split into a set of 8 x 8 submatrices and then changes the values of these matrices by multiplying each block with the secret shared key matrix. The encrypted image is constructed by merging all encrypted blocks. With this combination, the correlation between adjacent pixels in the ciphered image is effectively removed, and the level of unpredictability and uncertainty for the ciphered image is also enhanced. The suggested approach used the key space, entropy, histogram, antinoise attack, differential attack, and correlation coefficient to evaluate the performance of the encryption method. According to simulation findings, the proposed method offers a high level of security and efficiency, and resists attackers.