Introduction to webrtc protocol -- an article to understand dtls, SRTP, srtcp

DTLS effect

Packet transport layer security （ English ：Datagram Transport Layer Security, Abbreviation for DTLS）, Packet transport layer security , Is a communication protocol , Provide UDP The sending security of the protocol at the transport layer . It can provide TLS Similar security protection .DTLS Commonly used in streaming media .

DTLS And TLS

DTLS is similar to TLS intentionally except that DTLS has to solve two problems: packet lost and reordering. DTLS implements
packet retransmission
assigning sequence number within the handshake
replay detection.

DTLS be based on UDP Agreed ,OpenSSL Realized DTLS

stay WebRTC Use in DTLS There are two parts to it :

Datachannel Data channel . stay Datachannel In the data channel ,WebRTC Fully using the DTLS To negotiate and encrypt and decrypt

MediaChannel Media channel . In the media channel WebRTC Use SRTP To encrypt and decrypt data ,DTLS Is only used for key exchange ,RTP/RTCP For the sake of compatibility with historical equipment , Entirely by SRTP To achieve .