Chaos synchronization and cryptography for secure communications / Fatin Nabila Abd Latiff

Fatin Nabila , Abd Latiff (2021) Chaos synchronization and cryptography for secure communications / Fatin Nabila Abd Latiff. PhD thesis, Universiti Malaya.

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Abstract

Many Chaos-Based Cryptographic (CBC) methods, such as chaos-based secure communication, and chaos-based block/stream cipher, have been studied over the past decade. To the best of our knowledge, CBC is a new field of research in two areas, such as cryptography (computer and data security) and chaos (nonlinear dynamic system). For high security, encryption is one of the methods used to protect data against leakage. CBC describes chaos theory as a measure of communication techniques and computational algorithms to perform different cryptographic tasks in a cryptographic system in specific physical dynamic systems operating in chaotic systems. Chaos is an exciting phenomenon in various fields, such as physics, psychology, and biology in some systems. The theory of chaos provides the means to explain the phenomenon of chaos, control chaotic dynamic systems, and use the properties of chaos. In particular, the characteristics of chaos, such as robustness, merging property, sensitivity to initial conditions/parameter mismatches, the complexity of the structure and stochastic dynamics, which maps nicely with cryptographic requirements such as confusion, diffusion, complexity of the algorithm and deterministic pseudo-randomness, have been shown to be appropriate for the design of data protection means. Besides, the probability of chaotic synchronization, where the Master System (MS) (transmitter) drives the Slave System (SS)(receiver) via its output signal, has made it likely that chaotic systems could be used to enforce protection in communication systems. Many techniques, such as chaotic shift key and Chaos Masking (CM), were suggested, but many attack methods later showed them insecurity. There are also different modifications to these methods in the literature to improve safety, but almost all suffer from the same disadvantage. The implementation of chaotic security systems, therefore, remains a challenge. This work introduces a Fractional-Order (FO), such as Fractional-Order Newton-Leipnik System (FONLS) and Fractional-Order Neural Networks (FONNs), which could improve the security of existing methods. The complexity of FO systems is due to the inclusion and derivation of non-integer orders being addressed. If these two chaotic signals of equal power are combined and then used to transmit message signals, it may be difficult for intruders to use conventional attack methods because the chaotic carrier signal has added complexity. Based on this, we analyzed various initial conditions within the same parameters and found the best FO minimum value of FONLS. In this thesis, the second part of chaos-based secure communication is introducing a new encryption algorithm to improve the security of modern chaos-based communication systems. For secure communication that is reliable, secure, and has good performance, the focus is on developing Double Encryption System (DES). The combination of synchronization of chaos and symmetric encryption is called DES. In this thesis, theoretically and numerically, FONNs is formulated with multiple time delays and the stability of the chaotic systems and their safety are analyzed.

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