ZRTP: Extensions to RTP for Diffie-Hellman Key Agreement for SRTP
This document defines ZRTP, RTP (Real-time Transport Protocol) header extensions for a Diffie-Hellman exchange to agree on a session key and parameters for establishing Secure RTP (SRTP) sessions. The ZRTP protocol is completely self-contained in RTP and does not require support in the signaling protocol or assume a Public Key Infrastructure (PKI) infrastructure. For the media session, ZRTP provides confidentiality, protection against Man in the Middle (MitM) attacks, and, in cases where a secret is available from the signaling protocol, authentication. ZRTP can utilize three Session Description Protocol (SDP) attributes to provide discovery and authentication through the signaling channel.