A Four Level Speech Signal Encryption Algorithm
In this paper, the authors present a novel speech encryption algorithm based on four level of hash based encryption. Their approach integrates a modified time domain scrambling scheme with an amplitude scrambling method which masks the speech signal with algorithmic based noise by specific mixing. In this, they use different algorithm to encrypt the speech signal at different levels, i.e., they encrypt the original signal four times using different algorithm at each level. The output of one level makes the input of next level. As a result of this algorithm, the speech signal becomes more and more secure at each level.