Permutation-substitution image encryption scheme based on a modified chaotic map in transform domain

A new chaotic image encryption scheme based on permutation and substitution in the Fourier domain is presented. Fractional Fourier Transform (FRFT) is used before the encryption scheme to get a large degree of randomization. The permutation is achieved by Baker map and the substitution by a key-related-to-plain-image algorithm based on the modified Logistic map. Modification of the Logistic map is developed to increase the space of the encryption key, and hence increase the security. The key of the encryption algorithm dependents on the plain image, and thus, the cipher image is sensitive to both the initial key and the plain image to resist known-plaintext and chosen plaintext attacks. The key space is large and hence the algorithm can effectively resist brute-force attacks. The proposed scheme is examined using different performance evaluation metrics and the results prove that the proposed scheme is highly secure, and it can effectively resist different attacks.