Biblio

Cryptography algorithms play a critical role in information technology against various attacks witnessed in the digital era. Many studies and algorithms are done to achieve security issues for information systems. The high complexity of computational operations characterises the traditional cryptography algorithms. On the other hand, lightweight algorithms are the way to solve most of the security issues that encounter applying traditional cryptography in constrained devices. However, a symmetric cipher is widely applied for ensuring the security of data communication in constraint devices. In this study, we proposed a hybrid algorithm based on two cryptography algorithms PRESENT and Salsa20. Also, a 2D logistic map of a chaotic system is applied to generate pseudo-random keys that produce more complexity for the proposed cipher algorithm. The goal of the proposed algorithm is to present a hybrid algorithm by enhancing the complexity of the current PRESENT algorithm while keeping the performance of computational operations as minimal. The proposed algorithm proved working efficiently with fast executed time, and the analysed result of the generated sequence keys passed the randomness of the NIST suite.

The purpose of this paper is to improve the safety of chaotic image encryption algorithm. Firstly, to achieve this goal, it put forward two improved chaotic system logistic and henon, which covered an promoted henon chaotic system with better probability density, and an 2-dimension logistic chaotic system with high Lyapunov exponents. Secondly, the chaotic key stream was generated by the new 2D logistic chaotic system and optimized henon mapping, which mixed in dynamic proportions. The conducted sequence has better randomness and higher safety for image cryptosystem. Thirdly, we proposed algorithm takes advantage of the compounded chaotic system Simulation experiment results and security analysis showed that the proposed scheme was more effective and secure. It can resist various typical attacks, has high security, satisfies the requirements of image encryption theoretical.

In this work, an asymmetric cryptography method for information security was developed, inspired by the fact that the human body generates chaotic signals, and these signals can be used to create sequences of random numbers. Encryption circuit was implemented in a Reconfigurable Hardware (FPGA). To encode and decode an image, the chaotic synchronization between two dynamic systems, such as Hopfield neural networks (HNNs), was used to simulate chaotic signals. The notion of Homotopy, an argument of topological nature, was used for the synchronization. The results show efficiency when compared to state of the art, in terms of image correlation, histogram analysis and hardware implementation.

New attacks on existing algorithms have revealed various weaknesses. To overcome these weaknesses, researchers are searching for new ones. In this study, a new image encryption algorithm has been proposed to realize this aim. The most obvious component of the proposed image encryption algorithm is the cryptographic substitution box structure used to provide the confusion requirement. The original aspect of the substitution box structure according to similar studies in the literature is that the design was realized by using Lotka-Volterra chaotic system. The analysis results showed that both the substitution box structure and the image encryption algorithm provide the necessary criteria for data security.

The strength of the substitution box (S-box) determines the security of the cryptographic algorithm because it's the only nonlinear component in the block cipher. Because of the disadvantages of non-uniformity sequence and limited range in the one-dimension (1D) chaotic map, this paper constructs the logistic map and the sine map into a combined chaotic map, and a new S-box construction method based on this combined chaotic map is presented. Performance tests were performed on the S-box, including nonlinearity, linear probability, differential probability, strict avalanche criterion, bits independence criterion. Compared with others S-box, this result indicates that the S-box has more excellent cryptographic performance and can be used as a nonlinear component in the lightweight block cipher algorithm.

In this paper a novel random number generator is introduced and it is based on the Skew-tent discrete-time chaotic map. The RNG presented in this paper is made using the discrete-time chaotic map and chaotic sampling of regular waveform method together to increase the throughput and statistical quality of the output sequence. An explanation of the arithmetic model for the proposed design is given in this paper with an algebra confirmation for the generated bit stream that shows how it passes the primary four tests of the FIPS-140-2 test suit successfully. Finally the bit stream resulting from the hardware implementation of the circuit in a similar method has been confirmed to pass all NIST-800-22 test with no post processing. A presentation of the experimentally obtained results is given therefor proving the the circuit’s usefulness. The proposed RNG can be built with the integrated circuit.

The problems of synthesis of a digital data encryption system based on dynamic chaos in a research project carried out at the Department of Marine Electronics (SMTU) are considered. A description is made of the problems of generating a chaotic (random) signal in computer systems with calculations with finite accuracy.

With the deep research on coherent optical OFDM offset quadrature amplitude modulation OFDM/OQAM in these years, and the communication system exposed to potential threat from various capable attackers, which prompt people lay emphasis on encryption methods for transmission. Therefore, in this paper, we systematically discuss an encryption project with the main purpose of improving security in coherent optical OFDM/OQAM (CO-OFDM/OQAM) system, and the scheme applied the chaotic constellation scrambling (CCS) which founded on chaotic cross mapping to encrypt transmitted information. Besides, we also systematically discuss the basic principle of the encryption scheme for CO-OFDM/OQAM system. According to numerous studies and analysis on experiment data with caution, such as the performance of entropy, bit error rate (BER). It's conforms that the security of CO-OFDM/OQAM system have been enhanced.

In this paper, a novel Dynamic Chaotic Biometric Identity Isomorphic Elliptic Curve (DCBI-IEC) has been introduced for Image Encryption. The biometric digital identity is extracted from the user fingerprint image as fingerprint minutia data incorporated with the chaotic logistic map and hence, a new DCBDI-IEC has been suggested. DCBI-IEC is used to control the key schedule for all encryption and decryption processing. Statistical analysis, differential analysis and key sensitivity test are performed to estimate the security strengths of the proposed DCBI-IEC system. The experimental results show that the proposed algorithm is robust against common signal processing attacks and provides a high security level for image encryption application.

Traditional encryption algorithms are not suitable for modern mass speech situations, while some low-dimensional chaotic encryption algorithms are simple and easy to implement, but their key space often small, leading to poor security, so there is still a lot of room for improvement. Aiming at these problems, this paper proposes a new type of four-dimensional chaotic system and applies it to speech encryption. Simulation results show that the encryption scheme in this paper has higher key space and security, which can achieve the speech encryption goal.

Recently, new perspective areas of chaotic encryption have evolved, including fuzzy logic encryption. The presented work proposes an image encryption system based on two chaotic mapping that uses fuzzy logic. The paper also presents numerical calculations of some parameters of statistical analysis, such as, histogram, entropy of information and correlation coefficient, which confirm the efficiency of the proposed algorithm.

Chaos-based encryption is one of the promising cryptography techniques that can be used. Although chaos-based encryption provides excellent security, the finite precision of number representation in computers affects decryption accuracy negatively. In this paper, a way to mitigate some problems regarding finite precision is analyzed. We show that the use of maps with small Lyapunov exponents can improve the performance of chaotic encryption scheme, making it suitable for image encryption.

Dynamic random growth technique and a hybrid chaotic map which is proposed in this paper are used to perform block-based image encryption. The plaintext attack can easily crack the cat map, as it is periodic, and therefore cat map securely used in which it can eliminate the cyclical occurrence and withstand the plaintext attack's effect. The diffusion process calculates the intermediate parameters according to the image block. For the generation of the random data stream in the chaotic map, we use an intermediate parameter as an initial parameter. In this way, the generated data stream depends on the plain text image that can withstand the attack on plain text. The experimental results of this process prove that the proposed dynamic random growth technique and a hybrid chaotic map for image encryption is a secured one in which it can be used in secured image transmission systems.

Based on the Lyapunov stability theory, a novel adaptive synchronization method is proposed for three chaotic systems with different orders. Then the proposed method is applied to secure communication. This paper designs a novel multistage chaotic synchronized secure communication system in which the encrypted information signal is transmitted to the receiver after two chaotic masking, and then recovered at the synchronized receiver. Numerical results show the success in transmitting a continuous signal and a discrete signal through three synchronized systems.

This work presents a new method of encrypting and decrypting speech based on a chaotic key generator. The proposed scheme takes advantage of the best features of chaotic systems. In the proposed method, the input speech signal is converted into an image which is ciphered by an encryption function using a chaotic key matrix generated from a fractional-order chaotic map. Based on a deadbeat observer, the exact synchronization of system used is established, and the decryption is performed. Different analysis are applied for analyzing the effectiveness of the encryption system. The obtained results confirm that the proposed system offers a higher level of security against various attacks and holds a strong key generation mechanism for satisfactory speech communication.

Voice communication is an important need in daily activities whether delivered with or without technology. Telecommunication technology has accommodated this need by providing a wide range of infrastructure, including large varieties of devices used as intermediary and end devices. One of the cellular technologies that is very widely used by the public is GSM (Global System for Mobile), while in the military, trunked radio is still popular. However, the security systems of GSM and trunked radio have limitations. Therefore, this paper proposes a platform to secure voice data over wireless mobile communication by providing end-to-end encryption. This platform is robust to noise, real-time and remains secure. The proposed encryption utilizes multicircular permutations rotated by expanded keys as dynamic keys to scramble the data. We carry out simulations and testbed implementation to prove that application of the proposed method is feasible.

In network communication domain, one of the most widely used protocol for encrypting data and securing communications is the IPSec protocol. The design of this protocol is based on two main phases which are: exchanging keys phase and transferring data phase. In this paper we focus on enhancing the exchanging keys phase which is included in the security association (SA), using a chaotic cryptosystem. Initially IPSec is based on the Internet Key Exchange (IKE) protocol for establishing the SA. Actually IKE protocol is in charge for negotiating the connection and for authenticating both nodes. However; using IKE gives rise to a major problem related to security attack such as the Man in the Middle Attack. In this paper, we propose a chaotic cryptosystem solution to generate SA file for the connected nodes of the network. By solving a 4-Dimension chaotic system, a SA file that includes 128-bit keys will be established. The proposed solution is implemented and tested using FPGA boards.

PRIME protocol is a narrowband power line communication protocol whose security is based on Advanced Encryption Standard. However, the key expansion process of AES algorithm is not unidirectional, and each round of keys are linearly related to each other, it is less difficult for eavesdroppers to crack AES encryption algorithm, leading to threats to the security of PRIME protocol. To solve this problem, this paper proposes an improvement of PRIME protocol based on chaotic cryptography. The core of this method is to use Chebyshev chaotic mapping and Logistic chaotic mapping to generate each round of key in the key expansion process of AES algorithm, In this way, the linear correlation between the key rounds can be reduced, making the key expansion process unidirectional, increasing the crack difficulty of AES encryption algorithm, and improving the security of PRIME protocol.

In this paper, the two methods for ciphering are presented and compared. The aim is to reveal the suitability of chaotic neural network approach to ciphering compared to AES cipher. The durations in seconds of both methods are presented and the two methods are compared. The results show, that the chaotic neural network is fast, suitable for ciphering of short plaintexts. AES ciphering is suitable for longer plaintexts or images and is also more reliable.

Cryptography algorithms play a critical role in information technology against various attacks witnessed in the digital era. Many studies and algorithms are done to achieve security issues for information systems. The high complexity of computational operations characterises the traditional cryptography algorithms. On the other hand, lightweight algorithms are the way to solve most of the security issues that encounter applying traditional cryptography in constrained devices. However, a symmetric cipher is widely applied for ensuring the security of data communication in constraint devices. In this study, we proposed a hybrid algorithm based on two cryptography algorithms PRESENT and Salsa20. Also, a 2D logistic map of a chaotic system is applied to generate pseudo-random keys that produce more complexity for the proposed cipher algorithm. The goal of the proposed algorithm is to present a hybrid algorithm by enhancing the complexity of the current PRESENT algorithm while keeping the performance of computational operations as minimal. The proposed algorithm proved working efficiently with fast executed time, and the analysed result of the generated sequence keys passed the randomness of the NIST suite.

The purpose of this paper is to improve the safety of chaotic image encryption algorithm. Firstly, to achieve this goal, it put forward two improved chaotic system logistic and henon, which covered an promoted henon chaotic system with better probability density, and an 2-dimension logistic chaotic system with high Lyapunov exponents. Secondly, the chaotic key stream was generated by the new 2D logistic chaotic system and optimized henon mapping, which mixed in dynamic proportions. The conducted sequence has better randomness and higher safety for image cryptosystem. Thirdly, we proposed algorithm takes advantage of the compounded chaotic system Simulation experiment results and security analysis showed that the proposed scheme was more effective and secure. It can resist various typical attacks, has high security, satisfies the requirements of image encryption theoretical.

In this work, an asymmetric cryptography method for information security was developed, inspired by the fact that the human body generates chaotic signals, and these signals can be used to create sequences of random numbers. Encryption circuit was implemented in a Reconfigurable Hardware (FPGA). To encode and decode an image, the chaotic synchronization between two dynamic systems, such as Hopfield neural networks (HNNs), was used to simulate chaotic signals. The notion of Homotopy, an argument of topological nature, was used for the synchronization. The results show efficiency when compared to state of the art, in terms of image correlation, histogram analysis and hardware implementation.

With the development of wireless communication, the reliability and the security of data is very significant for the wireless communication. In this paper, a delayed feedback chaotic encryption algorithm based on polar codes is proposed. In order to protect encoding information, we make uses of wireless channels to extract binary keys. The extracted binary keys will be used as the initial value of chaotic system to produce chaotic sequences. Besides, we use the chain effects of delayed feedback, which increase the difficulty of cryptanalysis. The results of the theoretical analyses and simulations show that the algorithm could guarantee the security of data transmission without affecting reliability.

As a result of increasing the interest in developing the communication systems that use public channels for transmitting information, many channel problems are raised up. Among these problems, the important one should be addressed is the information security. This paper presents a proposed communication system with high security uses two encryption levels based on chaotic systems. The first level is chaotic scrambling, while the second one is chaotic masking. This configuration increases the information security since the key space becomes too large. The MATLAB simulation results showed that the Segmental Spectral Signal to Noise Ratio (SSSNR) of the first level (chaotic scrambling) is reduced by -5.195 dB comparing to time domain scrambling. Furthermore, in the second level (chaotic masking), the SSSNR is reduced by -20.679 dB. It is also showed that when the two levels are combined, the overall reduction obtained is -21.755 dB.

This paper explores using chaos-based cryptography for transmitting multimedia data, mainly speech and voice messages, over public communication channels, such as the internet. The secret message to be transmitted is first converted into a one-dimensional time series, that can be cast in a digital/binary format. The main feature of the proposed technique is mapping the two levels of every corresponding bit of the time series into different multiple chaotic orbits, using a simple encryption function. This one-to-many mapping robustifies the encryption technique and makes it resilient to crypto-analysis methods that rely on associating the energy level of the signal into two binary levels, using return map attacks. A chaotic nonautonomous Duffing oscillator is chosen to implement the suggested technique, using three different parameters that are assumed unknown at the receiver side. Synchronization between the transmitter and the receiver and reconstructing the secret message, at the receiver side, is done using a Lyapunov-based adaptive technique. Achieving stable operation, tuning the required control gains, as well as effective utilization of the bandwidth of the public communication channel are investigated. Two different case studies are presented; the first one deals with text that can be expressed as 8-bit ASCII code, while the second one corresponds to an analog acoustic signal that corresponds to the voice associated with pronouncing a short sentence. Advantages and limitation of the proposed technique are highlighted, while suggesting extensions to other multimedia signals, along with their required additional computational effort.