Speech encryption using circulant transformations

A new analog encryption technique using unitary circulant transformations of the sampled analog signal is proposed. This technique is less vulnerable to attack than other known schemes based on transposition (scrambling) of the signal components in the time or frequency domain. The new technique introduces primarily a phase distortion. A new distortion measure capable of quantifying phase distortion is proposed. An optimal speaker-specific key generation scheme is then developed for maximizing an objective function based on the new distortion measure.