Research On Encryption And Decryption Algorithm Of Audio With Chaotic Mapping

With the widespread and development of modern technology,the need for security to secure information is absolutely necessary to ensure safety;it is such a requisite block in the transmission section of any communication system.In this contest,many researchers have identified the possibility of applying dynamic and disordered behaviour of a chaotic system in cryptography.These chaotic systems have outstanding features such as high sensitivity to initial conditions/system parameters,erratic behaviour,high security,and simplicity.In symmetric encryption techniques,Information or data of any kind such as text,image,audio,and video can be protected using two different categories of ciphers namely;block cipher and stream cipher.Nevertheless,chaotic encryption algorithms arc designed to secure information from attackers.However,there are some challenges that need to be faced when using chaos theory in the field of cryptography such as data redundancy and all the chaotic maps which are not random.Some of them utilize various one-dimensional(1D)chaotic maps in the development of speech security systems.1D chaotic maps result in single simple predictable chaotic orbits.As a result,the attacker can obtain the initial states and/or system parameters of the chaotic map easily.Furthermore,the one-dimensional chaotic map suffers from small key space and weak security.The main contents of this thesis are as follows:The first part of this thesis accomplished a comprehensive survey on the chaotic maps and digital chaotic ciphers,and then proposed novel coupled chaotic systems(CCS)based on two-dimensional(2D)Henon map and one-dimensional(1D)Logistic map.The two chaotic maps have different parameter values and their orbits are compared according to a function to produce a pseudo-random bit stream,the system prevents revealing information about the chaotic maps used in the pseudo-random sequence generation(PRSGs)structure.The proposed algorithm is introduced to enhance the security,eliminate the problem of small/limited keyspace and also increase the dimension which in turn increases the nonlinearity.The second part explained the digitization processes,encryption and decryption algorithm processes,simulation,and results in analysis.The algorithm uses the chaotic iteration to generate the symmetric encryption keys and then carries out the exclusive OR(XOR)operation on the plaintext to form the ciphertext.The last part shows the background,design,experiments,and results from the discussion of the audio encryption and decryption application.The Application consists of many function calling.Each function has a particular task.In total there are four major processes involved in this software implementation,which includes;the main procedure,play area,recording,encryption,and decryption.The implementation is performed in MATLAB graphical user interface(GUI)and the results are observed.Security analysis demonstrates that the algorithm is very sensitive to the tiny change of the keys,and statistical analysis such as peak signal-to-noise(PSNR)and correlation shows that the algorithm can resist against statistical attacks.Experimental results demonstrate the effectiveness of the proposed scheme in terms of security.This paper makes in-depth research in the chaotic audio encryption and provides a reliable basis for the design and implementation of the chaotic encryption.