Secure voice over internet protocol based on combined secret key method

For more secure voice communication over Internet, the secure voice over internet protocol is proposed. The key agreement and the cipher text of voice packets transmission processes are related to the SIP, SDP and UDP. Parameters are negotiated using the SDP during the calling process for connection and key agreement, which is transported in the SIP packet body. The voice data are encrypted in groups and transported to secure communication server using UDP. Secure communication server forwards the cipher text packets to the receiver. Each secure voice communication over internet owns a different session key generated randomly and a different encryption key generated on the basis of key seeds according to random numbers and time-stamp, which guarantees security over Internet for voice communication users.