Cryptanalysis of a spatiotemporal chaotic cryptosystem (original) (raw)
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Recently a new chaotic encryption system has been proposed as a modified version of the chaotic cryptographic method based on iterating a logistic map. A fundamental weakness of this new cryptosystem is pointed out that allows for three successful cryptanalytic attacks.
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This paper proposes three different attacks on a recently proposed chaotic cryptosystem in [Li P, Li Z, Halang WA, Chen G. A stream cipher based on a spatiotemporal chaotic system. Chaos, Solitons & Fractals 2007;32:1867-76]. The cryptosystem under study displays weakness in the generation of the keystream. The encryption is made by generating a keystream mixed with blocks generated from the plaintext. The so obtained keystream remains unchanged for every encryption procedure. Moreover, its generation does neither depend on the plaintext nor on the ciphertext, that's to say, the keystream remains unchangeable for every plaintext with the same length. Guessing the keystream leads to guessing the key. This paper presents three possible attacks able to break the whole cryptosystem based on this drawback in generating the keystream.
A Stream Cipher based on Spatiotemporal Chaos and True Random Synchronization
IETE Journal of Research, 2017
Stream ciphers require the use of initialization vectors (IVs) to ensure that the same secret key produces different keystreams. It also synchronizes communication between two parties. However, there are many cryptanalytic attacks that exploit weaknesses in the IV setup of stream ciphers. In an effort to solve this problem, we introduce a chaos-based stream cipher that utilizes a new mode of synchronization called true random synchronization (TRSync). The stream cipher is designed based on spatiotemporal chaos while taking advantage of TRSync to resist various statistical attacks. The stream cipher operations also include data-dependent rotations and chaotic perturbation. As chaotic functions are inherently slow due to floating point operations, we utilize fixed point representation for higher efficiency. TRSync includes a true random number sequence (TRNS) into the synchronization process alongside the public IV. The IV is masked by the TRNS before being used to setup the cipher. Therefore, the cipher’s internal state cannot be manipulated by an attacker and constantly changes even if the secret key-IV pairs are constant. TRSync can also be used to secure other stream ciphers with IVs as described in this paper. The security of the proposed chaotic cipher is thoroughly analyzed in terms of randomness, periodicity, entropy, balance, correlation, and complexity.
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Chinese Journal of Physics, 2003
A new scheme for generating good pseudo-random numbers, based on the composition of chaotic maps, is studied. In this method, hereafter called the chaotic stream cipher, one first uses a known chaotic dynamical system to generate a sequence of pseudo-random bytes, then applies certain permutations to them, using the discretized version of another two-dimensional chaotic map. Standard statistical tests of this scheme, as well as other known chaos-based random number generators, are performed and compared. We show that this new scheme can generate a high percentage of usable pseudo-random numbers, while maintaining a large enough key space for potential use in encryptions.
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2003
Using a new method to extract the data from various one-dimensional chaotic maps, we show that there is a nice correlation between the sign of the Lyapunov exponent of the maps and whether the extracted data form a good set of pseudo-random numbers using various well-known criteria.
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This paper discusses mixing of chaotic systems as a dependable method for secure communication. Distribution of the entropy function for steady state as well as plaintext input sequences are analyzed. It is shown that the mixing of chaotic sequences results in a sequence that does not have any state dependence on the information encrypted by them. The generated output states of such a cipher approach the theoretical maximum for both complexity measures and cycle length. These features are then compared with some popular ciphers.
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Communications in Nonlinear …, 2011
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 (one-parameter) 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.
Cryptanalytic methods in chaotic cryptosystems
6 pages, 6 figures.-- Communication presented at the 5th World Multiconference on Systemics, Cybernetics and Informatics and 7th International Conference on Information System Analysis and Synthesis (SCI/ISAS 2001, Orlando, Florida, Jul 22-25, 2001). In recent years, telecommunications networks have undergone an explosive growth. As a consequence, there has been a strong demand of information protection mechanisms. Many cryptosystems based on chaos have been proposed, although little or no critical analysis has been made about the security and cryptographic robustness of these algorithms. In this paper we present our tools to examine some of these algorithms from a cryptographic perspective, showing many vulnerabilities that can be exploited to successfully break them. We conclude that most of the chaotic cryptosystems are very insecure and cumbersome, thus, unreliable and impractical for real applications. Peer reviewed
Cryptanalysis of dynamic look-up table based chaotic cryptosystems
Physics Letters A, 2004
In recent years many chaotic cryptosystems based on Baptista's seminal work have been proposed. We analyze the security of two of the newest and most interesting ones, which use a dynamically updated look-up table and also work as stream ciphers. We provide different attack techniques to recover the keystream used by the algorithms. The knowledge of this keystream provides the attacker with the same information as the key and thus the security is broken. We also show that the dependence on the plaintext, and not on the key, of the look-up table updating mechanism facilitates cryptanalysis.
Cryptanalysis of a chaotic encryption system
Physics Letters A, 2000
Recently a new chaotic encryption system has been proposed by E. Alvarez et al. In this paper, several weaknesses of this cryptosystem are pointed out and four successful cryptanalytic attacks are described.