Development of speech encryption Algorithms using multiple chaotic And hyper chaotic maps

Abstract

Transmission and storage of speech in digital form carries onfidential and important personal information. Due to the development of advanced technologies, high levels of security systems are the need of the hour to protect the information from the eavesdroppers. Encryption is a mechanism used to safeguard the spoken information on a public network by onverting into unreadable format. To convert the original signal into unintelligible form, permutation and substitution process have been carried out i.e. scrambling is done for confusing the input signal. Chaotic maps are used to generate pseudo random numbers with high randomness to encrypt the input signal using permutation and substitution process. The challenges in speech encryption techniques include low-key space, chances of residual information in encrypted speech, poor quality of speech received at receiver s end and usage of higher bandwidth. In order to address and overcome such issues, a tested speech encryption algorithms are applied in this research using multiple chaotic maps and hyper chaotic maps in the compressed domain. The major issue in one dimensional chaotic map and single chaotic map is in its limited randomness compared to multi-dimensional and multiple chaotic maps. The methods proposed in this thesis is that the chaotic maps namely Tent map, Sin map, Logistic map, Bernoulli s map, Quadratic map, Bet map used to derive random number generation. In order to enhance the key space, multiple-chaotic system is developed by combining any two different chaotic maps to achieve the Number of Sample Change Rate (NSCR) against the standard range of 99.5% and Unified Average Changing Intensit newline