Module srtp 

SRTP (RFC 3711) for SIP media, keyed by SDES (RFC 4568).

(feature sip) A SIP trunk or softphone that offers RTP/SAVP with an a=crypto line sends its media encrypted and authenticated. This module is the packet layer: SrtpSession::protect turns an RTP packet into an SRTP packet, and SrtpSession::unprotect checks and decrypts one. CryptoAttribute parses and prints the SDP line that carries the keys.

Supported: the AES_CM_128_HMAC_SHA1_80 and AES_CM_128_HMAC_SHA1_32 suites (the ones every SDES endpoint implements), a key derivation rate of zero, and no MKI. SRTCP is not implemented, since the agent does not send RTCP; an offer is answered for RTP only.

SDES sends the keys in the SDP body, so they are only as secret as the signalling. Use SIP over TLS when the keys must not be readable on the network path.

Structs

CryptoAttribute

An SDES a=crypto attribute (RFC 4568).

MasterKey

A master key and salt, from which the session keys are derived.

SrtpSession

One direction of an SRTP stream: protect what you send with your key, unprotect what you receive with the peer’s.

Enums

SrtpError

Why a packet failed SrtpSession::unprotect.

SrtpSuite

An SRTP crypto suite.