The growing use of ICT exposes exchanges to certain risks, which require the existence of adequate security measures of information. The data encryption is often an effective way to meet these requirements of security and confidentiality. This paper present a novel cryptosystem by block depended on the secret key and subkeys and respect the fundamental principles of modern cryptography for encrypting images, since images have some intrinsic features such as large data capacity, strong correlation between adjacent pixels and high redundancy of information. The proposed cryptosystem is based on rekeying to apply permutation inter-intra pixel of each block according to the secret key and subkeys using a random, nonlinear, dynamic and secret scrambled technique there be called RNDSS. Experimental tests demonstrate the high security of the proposed cryptosystem with RNDSS technique and show the high sensitive dependence to any subtle change in the secret key, which guarantees the security against brute force attacks.

Recent researches of image encryption algorithms have been increasingly based on chaotic systems. This paper, a new image encryption scheme which employs. The idea is to associate the Hénon attractor and the logistics map, for the construction of a new secret key cryptosystem. We generate values through of the logistics map that will be added to the pixels of the plaintext image. This result modulo 256 will be permuted to another position of the encrypted image. The calculation of this permutation is deducted from the Hénon attractor, which is 2-dimensional, in order to have a significantly increasing the resistance to attacks. The proposed system has the advantage of bigger key space (about 180 bits); high security analysis such as key space analysis, statistical analysis and sensitivity analysis were carried out. The results demonstrate that the proposed system is highly efficient and a robust system.