Houcemeddine Hermassi

Security analysis of an image encryption algorithm based on a DNA addition combining with chaotic maps

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. Then, a chosen plaintext attack on the invertible encryption block is described, where, the attacker can illegally decrypt the ciphered image by a temporary access to the encryption machinery.

Security analysis of image cryptosystems only or partially based on a chaotic permutation

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 proposed image encryption scheme based on shuffling the pixel bits inspired from other works is treated as a case study. By applying a chosen plaintext attack, we demonstrate that a hacker can determine the permutation vectors (matrixes) used to permute the pixels bits or the pixels themselves and exploit them to reveal the plain image.

Improvement of an image encryption algorithm based on hyper-chaos

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 concerns the two Boxes, P-Box and S-Box, which composed the original cryptosystem. Compared with classical encryption schemes, AES and Triple-DES, the new version of the cipher shows a better performances in rapidity, in confusion and in the key sensitivity.

Breaking an image encryption scheme based on a spatiotemporal chaotic system

In this paper, we describe a cryptanalysis of image encryption scheme recently proposed by Chun-Yan Song, Yu-Long Qiao, and Xing-Zhou Zhang. The scheme is based on a spatiotemporal chaos with a dynamic keystream generator, and its security is claimed to rely in utilized the plainimage in the keystream generation process to obtain a different keystream for every plainimage/cipherimage pair. However, two flaws are investigated and prove that the security of the proposal against chosen plaintext attack is groundless. Simulations conducted demonstrate that the plainimage can be recovered under partial attack with an acceptable perceptual quality. Moreover, a total break is possible, but a large number of plain-image/cipher-image pairs is needed. HighlightsA cryptanalysis of an image encryption scheme based on spatiotemporal chaos is presented.We gave a complete and partial break of the cryptosystem under study.We prove that the studied cryptosystem is not sufficiently secure against chosen plaintext attack.Results suggest that a partial attach needs smaller number of plain/ciphered images with acceptable perceptual qualities.

Chaotic watermark for blind forgery detection in images

In this paper, a new chaos based watermarking scheme for effective tamper detection in images is proposed. The proposed scheme is able to detect any possible forgery and spot the areas which have been tampered. To improve the efficiency of the proposed scheme, a binary watermark is constructed from the image itself, which makes the watermark unique for every image and guarantee the blindness in the detection process. To guarantee the security of the proposed scheme, chaotic maps are used to complicate the embedding and the detection process to reduce the vulnerability to different attacks. Experimental results and security analysis show that the proposed scheme achieves superior tamper detection under common attacks.

Security analysis and improvement of a partial encryption scheme

This paper proposes to cryptanalyze a partial image encryption scheme. Security weaknesses were found in the cryptosystem consisting in the generation of the keystream. We then propose a modified version of the partial encryption scheme to enhance its security together with keeping the benefit of encrypting a reduced amount of data. Our contributions can be resumed in two points : we will first show the insecurity of the cryptosystem under study then we will propose a remedy to resist the described attacks.

A modified hyperchaos based image cryptosystem

In this paper, we propose to enhance an image cryptosystem proposed in [1]. The enhanced version of the cryptosystem has been made to resist against the attacks proposed in [2]. The proposed modified algorithm have also a better performance than the original one.

A joint encryption-compression codec for speech signals using the ITU-T G.711 standard and chaotic map

We propose to incorporate encryption procedure into the lossy compression of voice data PCM(Pulse Code Modulation) based on the A-law approximation quantization. The proposed codec CPCM (Chaotic Pulse Code Modulaion) will join the encryption to the compression of the voice data. This scheme provides the same compression ratio given by the PCM codec, but with an unintelligible content. Comparisons with many used schemes have been made to highlight the proposed method in terms of security and rapidity. CPCM codec can be a better alternative to Compress-then-encrypt classical methods which is a time and resource consuming and non suitable for real-time multimedia secure transmission.

Watermarking and encryption scheme to secure multimedia information

Thanks to the development of information technology, fraud has multiplied, and many protection techniques have emerged to improve the security of our information, such as encryption, steganography and watermarking. In this paper we will present a novel scheme to secure multimedia information. Our aim is to increase the security of transmitted signals. First we improved an encryption algorithm based on chaotic iteration of the Logistics map. Then, we developed an algorithm to watermark information by using DCT method to insert message. Simulations and discussions of our method are presented to prove the efficiency of our proposition.

A new secure and efficient scheme of ADPCM encoder based on chaotic encryption

This paper presents a new secure variant of ADPCM encoders that are adopted by the CCITT as Adaptive Differential Pulse Code Modulation. This version provides encryption and decryption of voice simultaneously with operations ADPCM encoding and decoding. The evaluation of the scheme showed better performance in terms of speed and security.