SRTP

SRTP stands for Secure Real-time Transport Protocol. It adds security mechanisms to RTP, a protocol commonly used to carry audio and video during live communications. Depending on the negotiated profile, SRTP provides confidentiality, message authentication and replay protection for media packets. Its purpose is to protect the media stream rather than the signalling messages that set up a call.

A working SRTP session requires compatible security settings and a way for the participants to establish the necessary keys. Those details depend on the surrounding call architecture. Signalling encryption and media encryption are complementary: protecting one does not automatically protect the other. Network troubleshooting must also distinguish an encryption mismatch from packet loss, latency or an incorrect media destination. SRTP should not be described as proof of end-to-end encryption across every intermediary. The points at which media is decrypted, processed or re-encrypted are relevant when assessing a complete calling system's security properties.