Rhouma Rhouma

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This paper reports a detailed cryptanalysis of a recently proposed encryption scheme based on the logistic map [A. Pisarchik et al., Chaos 16, 033118 (2006)]. Some problems are emphasized concerning the key space definition and the implementation of the cryptosystem using floating-point operations. It is also shown how it is possible to reduce considerably(More)
In this paper, we propose to cryptanalyse an encryption algorithm which combines a DNA addition and a chaotic map to encrypt a gray scale image. Our contribution consists on, at first, demonstrating that the algorithm, as it is described, is non-invertible, which means that the receiver cannot decrypt the ciphered image even if he posses the secret key.(More)
In this paper a piecewise linear chaotic map (PWLCM) is used to build a new digital chaotic cryptosystem. The characteristics of PWLCM are very suitable for the design of encryption schemes. The implicit digital degradation problem of PWLCM has been eluded through the discretization of the phase space. The accuracy, efficiency and security of the proposed(More)
The substitution box is an essential element in cryptographic algorithms. Indeed, the S-box guarantees the confusion and nonlinearity properties required by secure block ciphers. In this study, we choose the Rossler system to generate a chaotic S-box. Proposed approach is tested for six criteria, which are bijectivity, nonlinearity, strict avalanche(More)
In this paper, a novel steganographic scheme is proposed based on chaotic map in the DCT domain. The proposed method apply the DCT on the cover image, scan the AC coefficients in a zigzag form from the least significant to the most significant one, this scan will lead us eventually to precise the embedding positions through a chaotic function as well as the(More)
The paper proposes breaks for the permutation methods adopted in the chaos-based image cryptosystems. By a careful examination on the most chaotic image cryptosystems we can find that the permutation process constitute the main step or, in some cases, the only step to create the confusion. It can be applied on the pixels or on the pixel bits. A recently(More)
In this paper, we propose to enhance a recently proposed image cryptosystem based on hyper-chaos. The updated version has been builded to resist against attacks made to break the original one and to make it faster. The modification touch on the two Boxes, P-Box and S-Box, which composed the original cryptosystem. Compared with classical encryption scheme,(More)