University of Khartoum

Design & Implementation Of An Analog Voice Encryption System Using Dsp

Design & Implementation Of An Analog Voice Encryption System Using Dsp

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Title: Design & Implementation Of An Analog Voice Encryption System Using Dsp
Author: Alsadig, Amna Emad Alsammani
Abstract: Encryption is one of the most widely used methods to ensure mobile and wireless communications security. An analog voice encryption system is designed and implemented to overcome bandwidth expansion and high delay of digital encryption systems. The Design was implemented using the Fast Fourier Transform (FFT) algorithm which is based on permuting FFT coefficients in the frequency domain using a generated key. The algorithm is designed to provide the least residual intelligibility in the recovered speech, ability to send voice in channels with different bandwidths along with high security and acceptable recovered quality. Design and implementation are carried out using MATLAB. The proposed system consists of a key generation module, a transmitter module and a receiver module. Transmitter and receiver modules uses Digital Signal Processing (DSP) tools and techniques to scramble and descramble the input speech respectively using a key generated by the key generation module. Results showed that, the least residual intelligibility in the scrambled speech is found at a 90% Hamming Distance (HD) probability with no bandwidth expansion and a large key space that raise the security level. In spite that the proposed system was able to overcome digital schemes limitations, it introduced high amplitude distortion and added noise at output of the receiver. These problems can be avoided by using an amplifier and a bandpass filter with the appropriate specifications in the receiver.
URI: http://khartoumspace.uofk.edu/123456789/25773
Date: 2017


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