Analysis of the encoding scheme for CS-ACELP codec for secured VoIP communication

Data security is one of the major concerns for digital data as well as voice transmission through non-privatized networks. Hence, a significant amount of research work is needed to provide reliable and secured data/voice transmission. The CS-ACELP algorithm based G.729 codec is standardized as voice codec by ITU-T for multimedia and Voice over Internet Protocol (VoIP) applications. The encoding scheme described in this paper, for CS-ACELP speech codec provides on-fly (while processing the speech frame) security for the encoded data, which avoids the use of various complex encryption, and decryption algorithms in order to provide secured speech transmission. This method is based on the periodically changing the track sequence of fixed codebook index for every 100 ms speech samples sampled at a rate of 8000 samples per second and also, adapting a new technique to encode the fixed codebook index. This paper, presents an easy and efficient way of providing data security for G.729 codec. The experimental results show that similar speech quality can be obtained without compromising with additional cost and transmission bandwidth.