An srtp_t points to an SRTP session structure.
The typedef srtp_t is a pointer to a structure that represents an SRTP session. This datatype is intentially opaque in order to separate the interface from the implementation.
An SRTP session consists of all of the traffic sent to the RTP and RTCP destination transport addresses, using the RTP/SAVP (Secure Audio/Video Profile). A session can be viewed as a set of SRTP streams, each of which originates with a different participant.