DTLS Protocol Référence
Référence pour Datagram TLS: TLS semantics sur UDP pour encrypted datagram communication.
DTLS Design
DTLS (RFC 9147) provides TLS security over UDP, preserving TLS handshake and record semantics. Since UDP is unreliable, DTLS adds retransmission timers and explicit sequence numbers (epoch + seq). Handshake messages include fragment offsets to support reassembly. The protocol handles reordering and loss via the epoch mechanism. DTLS 1.3 simplifies the handshake and removes ChangeCipherSpec. DTLS-SRTP profiles key derivation for WebRTC media.
- retransmission
- Handshake reliability
- epoch
- Sequence numbering
- fragmentation
- Handshake reassembly
timer-basedper key changeoffset + lengthUse Cases
WebRTC uses DTLS 1.3 for peer-to-peer media encryption (via DTLS-SRTP). CoAP uses DTLS for IoT security. DTLS avoids TCP head-of-line blocking, important for real-time media. Connection IDs (DTLS 1.3) enable connection migration across IP changes. Anti-replay windows discard duplicate packets. The protocol is stateful and requires session management. DTLS performance approaches TLS with proper implementation.
- WebRTC
- Media encryption
- CoAP
- IoT security
- CID
- Connection migration
DTLS-SRTPconstrained devicesDTLS 1.3