ANALOG SPEECH ENCRYPTION USING FFT AND DCT TECHNIQUES

Abstract

Speech encryption is becoming important day by day for the security of voice communication network. There are two possible ways through 'which speech encryption can be achieved (i) Digital encryption (ii) Analog encryption., Analog encryption is applicable to the situations where the transmission channel is analog. Analog speech encryption using FFT and DCT techniques has been implemented using HYPERSIGNALDSP software package, TMS 320C25 andTURBO C. Encryption process comprises of transform domain scrambling. Permutation operation used for encryption has been thoroughly- analysed'. Objective, measures have been discussed and computed for encrypted and. recovered speech. Performance Analysis has been made with help of objective measures and graphical representation of encrypted and recovered speech in time -domain and -frequency domain. The result have been found to be quitctory.