secure realtime transport protocol (SRTP)

The Secure Realtime Transport Protocol (SRTP) is the encrypted version of the Realtime Transport Protocol(RTP). It is used in Internet telephony for secure transmission of voice traffic between subscribers.

The SRTP protocol is described in RFC 3711 and is used for authentication and end-to-end encryption( E2EE) of the RTP payload according to the Advanced Encryption Standard( AES).

Compared to the Realtime Transport Protocol (RTP), SRTP has been extended by four bytes to transmit identity control information. SRTP uses AES encryption with a key length of 128 bits by default and since it does not have its own key management for master key( MK) management, key management is done by MultimediaInternet Keying( MIKEY).