Improvement of hill's classical method in image cryptography

Abstract

In this paper, we will introduce a new color image encryption algorithm. These images are of arbitrary sizes (n, m). This technique is based on a coupling of two chaotic maps; Namely, the logistics map and the PWLCM map. These two maps constructed and merged by a secret function f; which transforms two real from the interval [0 1] into number a real of the same interval. For confusion, we will use an improvement of the classical method of HILL. This improvement is none other than an affine transformation assured by a square matrix of order three with coefficient in the ring Z / 256Z. To this invertible matrix; we add a chaotic translation vector, this dynamic vector is modified at each iteration by another matrix of any order tree with coefficient in the ring Z / 256Z. A chaotic permutation in the ring Z / 3nmZ will be applied to the entire color image Finally, to avoid any differential attack, a new operating mode will be installed.The simulations carried out on the whole database showed that our new encryption technique is protected against any known attack