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EXACT AND ASYMPTOTIC SYNCHRONIZATION OF A NEW WEAKLY COUPLED MAPS SYSTEM
, 2009
"... Abstract. The paper deals with the synchronization of a new statistically highly performant function firstly introduced by Lozi. The synchronization is reached via observers which reconstruct all the states of the original system, using only a partial information of it. The map has been rewritten as ..."
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Abstract. The paper deals with the synchronization of a new statistically highly performant function firstly introduced by Lozi. The synchronization is reached via observers which reconstruct all the states of the original system, using only a partial information of it. The map has been rewritten as a piecewise affine one, which allows to design two types of observers: an exact (deadbeat) observer, and an asymptotic observer. Both observers have been analysed and compared; the deadbeat observer guarantees an exact convergence; however, synchronization can not be preserved in an autonomous regime (if the observer is switched off), because the map is highly chaotic, and the trajectories diverge due to the finite computer precision. The asymptotic observer is more robust in case of noise, but the convergence is slower, and the error converges to zero only asymptotically. In the latter case, several observers have to run in parallel, and the criteria to select the converging one are derived. Keywords. pseudorandom generators. 1
Survey: image encryption using Salsa20
 International Journal of Computer Science Issues
"... In present times, multimedia protection is becoming increasingly jeopardized. Therefore numerous ways of protecting information are being utilized by individuals, businesses, and governments. In this paper, we survey Salsa20 as a method for protecting the distribution of digital images in an efficie ..."
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In present times, multimedia protection is becoming increasingly jeopardized. Therefore numerous ways of protecting information are being utilized by individuals, businesses, and governments. In this paper, we survey Salsa20 as a method for protecting the distribution of digital images in an efficient and secure way. So, we performed a series of tests and some comparisons to justify salsa20 efficiency for image encryption. These tests included visual testing, key space analysis, histogram analysis, information entropy, encryption quality, correlation analysis, differential analysis, sensitivity analysis and performance analysis. Simulation experiment has validated the effectiveness of the Salsa20 scheme for image encryption.
Cryptanalysis of a family of selfsynchronizing chaotic stream ciphers
, 903
"... Unimodal maps have been broadly used as a base of new encryption strategies. Recently, a stream cipher has been proposed in the literature, whose keystream is basically a symbolic sequence of the (oneparameter) logistic map or of the tent map. In the present work a thorough analysis of the keystrea ..."
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Unimodal maps have been broadly used as a base of new encryption strategies. Recently, a stream cipher has been proposed in the literature, whose keystream is basically a symbolic sequence of the (oneparameter) logistic map or of the tent map. In the present work a thorough analysis of the keystream is made which reveals the existence of some serious security problems.
Hill Cipher Modification based on PseudoRandom Eigenvalues
"... Abstract: The Hill cipher is resistant to bruteforce and statistical attacks, but it can be broken with a known plaintextciphertext attack (KPCA). In this paper, we propose a modification of the Hill cipher, HCMPRE, which is still resistant to bruteforce and statistical attacks, and is resistant ..."
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Abstract: The Hill cipher is resistant to bruteforce and statistical attacks, but it can be broken with a known plaintextciphertext attack (KPCA). In this paper, we propose a modification of the Hill cipher, HCMPRE, which is still resistant to bruteforce and statistical attacks, and is resistant also to KPCA due to dynamic encryption key matrix generating. With the modification, the new HCMPRE can be applied widely in the systems which need high security (e.g., image encryption). Experimental results show that the proposed modification is significantly more effective in the encryption quality of images than original Hill cipher and its known modifications (HCMPT, HCMH, HCMHMAC, and HCMEE) in the case of images with large single colour areas, and slightly more effective otherwise. HCMPRE is about two times faster than HCMEE and HCMHMAC and four times faster than HCMH in the frame of our experiments.
A BASIC FRAMEWORK FOR THE CRYPTANALYSIS OF DIGITAL CHAOSBASED CRYPTOGRAPHY
, 811
"... Chaotic cryptography is based on the properties of chaos as source of entropy. Many different schemes have been proposed to take advantage of those properties and to design new strategies to encrypt information. However, the right and efficient use of chaos in the context of cryptography requires a ..."
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Chaotic cryptography is based on the properties of chaos as source of entropy. Many different schemes have been proposed to take advantage of those properties and to design new strategies to encrypt information. However, the right and efficient use of chaos in the context of cryptography requires a thorough knowledge about the dynamics of the selected chaotic system. Indeed, if the final encryption system reveals enough information about the underlying chaotic system it could be possible for a cryptanalyst to get the key, part of the key or some information somehow equivalent to the key just analyzing those dynamical properties leaked by the cryptosystem. This paper shows what those dynamical properties are and how a cryptanalyst can use them to prove the inadequacy of an encryption system for the secure exchange of information. This study is performed through the introduction of a series of mathematical tools which should be the basic framework of cryptanalysis in the context of digital chaosbased cryptography. Index Terms — chaos, cryptography, entropy, wavelet transforms
Integrated ConfusionDiffusion Mechanisms for Chaos Based Image Encryption” Computer and Information
 Technology Workshops, 2008. CIT Workshops 2008. IEEE 8th International Conference, Publication Year: 2008 , Page(s): 260
"... Most blockcipher image encryption schemes based on Chaos theory have independent modules for confusion and diffusion processes. None of the schemes thus far use chaos theory in the diffusion modules thus not utilizing the capabilities of chaos to the fullest extent. We can do better: we integrate ..."
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Most blockcipher image encryption schemes based on Chaos theory have independent modules for confusion and diffusion processes. None of the schemes thus far use chaos theory in the diffusion modules thus not utilizing the capabilities of chaos to the fullest extent. We can do better: we integrate these mechanisms into a single step, thus making the encryption process efficient. This paper presents three novelties: (a) we extend 2D images to 3D by using grayscale image intensities in 8bit binary form (b) we embed the diffusion mechanism into confusion by applying the 3D Baker map based confusion algorithm. Thus, the diffusion process is accomplished by a permutation of binary bits in the third dimension, eliminating the need for a separate diffusion process and (c) we extend the proposed method to color images by using the 24bit color information. Color image encryption is usually performed by encrypting each channel independently and then combining these to get the encrypted image. We demonstrate that with this simplistic approach, decrypting even a single channel would reveal reasonable information contained in the image. In our approach, this drawback is eliminated because of the inherent dependence between the data contained in all the channels, thus highlighting the inherent superiority of the proposed algorithm for color image security.
Efficient chaotic permutations for image encryption algorithms
"... Permutation is widely used in cryptographic algorithm. Recently, a number of candidate instructions have been proposed to efficient compute arbitrary bit permutations. Among these, we present the most attractive methods and having good inherent cryptographic properties. We propose to control it by t ..."
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Permutation is widely used in cryptographic algorithm. Recently, a number of candidate instructions have been proposed to efficient compute arbitrary bit permutations. Among these, we present the most attractive methods and having good inherent cryptographic properties. We propose to control it by the perturbed chaotic maps that we studied in [1]. Then, we measure the efficiency of the obtained chaotic permutation methods on a standard image. This study allows choosing a good chaotic permutation method to be used in a chaotic cryptosystem. 1.
Breaking a SCCNNbased Chaotic Masking Secure Communication System
, 2009
"... This paper studies the security of a chaotic cryptosystem based on Chua’s circuit and implemented with State Controlled Cellular Neural Networks (SCCNN). Here we prove that the plaintext can be retrieved by bandpass filtering of the ciphertext or by using an imperfect decoder with wrong receiver pa ..."
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This paper studies the security of a chaotic cryptosystem based on Chua’s circuit and implemented with State Controlled Cellular Neural Networks (SCCNN). Here we prove that the plaintext can be retrieved by bandpass filtering of the ciphertext or by using an imperfect decoder with wrong receiver parameters. In addition we find that the key space of the system can be reduced notably, and the required resolution of the parameter values to recover a meaningful plaintext is as coarse as 5%, easing a bruteforce attack. The system parameters can be determined with high precision through the analysis of the decoding error produced by the mismatch between the parameters of receiver and transmitter.
A Novel Pseudo Random Bit Generator Based on Chaotic Standard Map and its Testing
"... Abstract: During last one and half decade an interesting relationship between chaos and cryptography has been developed, according to which many properties of chaotic systems such as: ergodicity, sensitivity to initial conditions/system parameters, mixing property, deterministic dynamics and structu ..."
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Abstract: During last one and half decade an interesting relationship between chaos and cryptography has been developed, according to which many properties of chaotic systems such as: ergodicity, sensitivity to initial conditions/system parameters, mixing property, deterministic dynamics and structural complexity can be considered analogous to the confusion, diffusion with small change in plaintext/secret key, diffusion with a small change within one block of the plaintext, deterministic pseudo randomness and algorithmic complexity properties of traditional cryptosystems. As a result of this close relationship, several chaos based cryptosystems have been put forward since 1990. In one of the stages of the development of chaotic stream ciphers, the application of discrete chaotic dynamical systems in pseudo random bit generation has been widely studied recently. In this communication, we propose a novel pseudo random bit generator (PRBG) based on two chaotic standard maps running sidebyside and starting from random independent initial conditions. The pseudo random bit sequence is generated by comparing the outputs of both the chaotic standard maps. We also present the detailed results of the statistical testing on generated bit sequences, done by using two statistical test suites: the NIST suite and DIEHARD suite, which are developed independently and considered the most stringent statistical test suites to detect the specific characteristics expected of truly random sequences.