  In this paper, a high dimensional chaotic systems based mixed keystream
generator is proposed to secure the voice data. As the voice-based
communication becomes extensively vital in the application areas of military,
voice over IP, voice-conferencing, phone banking, news telecasting etc. It
greatly demands to preserve sensitive voice signals from the unauthorized
listening and illegal usage over shared/open networks. To address the need, the
designed keystream generator employed to work as a symmetric encryption
technique to protect voice bitstreams over insecure transmission channel. The
generator utilizes the features of high dimensional chaos like Lorenz and Chen
systems to generate highly unpredictable and random-like sequences. The
encryption keystream is dynamically extracted from the pre-treated chaotic
mixed sequences, which are then applied to mask the voice bitstream for
integrity protection of voice data. The experimental analyses like
auto-correlation, signal distribution, parameter residual deviation, key space
and key-sensitivity demonstrate the effectiveness of the proposed technique for
secure voice communication.
