DTLS-SRTP (DTLS Extension to Establish Keys for SRTP)

Also known as: RFC 5764

DTLS-SRTP (RFC 5764) is a keying mechanism that runs a DTLS handshake over the media path to derive SRTP master keys, binding the media session to certificate fingerprints exchanged in SDP over signalling. It is the standard media-plane key agreement for WebRTC and is increasingly adopted in modern IMS deployments as a stronger alternative to SDES, whose keys travel in the clear inside SIP.

Categories: Security ControlsProtocols and StandardsEncryption and Cryptography

DTLS-SRTP in context

Security controls in telecom span signaling firewalls (SS7/Diameter/GTP screening at the network edge), transport encryption (IPsec, TLS, PRINS), identity and access on OSS/BSS, and monitoring at both the packet and log level. Controls are audited against GSMA FS.11/FS.19/FS.20/FS.36 and, in Europe, NIS2 sectoral rules.

Telecom security is written into standards from 3GPP, GSMA, ETSI, IETF and ITU-T. Understanding which body owns which specification, and how the specs interlock (for example 3GPP TS 33.501 with GSMA FS.34 for 5G SBA security), is essential for both design and audit work.

To place DTLS-SRTP in the wider telecom-security picture, review SRTP, HKDF, XMPP, NAF, DoT and DOCSIS.

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