HKDF (HMAC-based Key Derivation Function)

Also known as: HMAC-based KDF

HKDF (RFC 5869) is a two-step extract-then-expand KDF built on HMAC. It is the standard KDF for TLS 1.3, IKEv2, Noise and modern secure messaging, and is used inside 5G SBA where TLS 1.3 traffic keys are derived. HKDF provides strong output separation through its info and salt parameters.

Categories: Security ControlsProtocols and StandardsEncryption and Cryptography

HKDF in context

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

Telecom security is written into standards from 3GPP, GSMA, ETSI, IETF and ITU-T. Understanding which body owns which specification, and how they interlock, is essential for both design and audit work.

To place HKDF in the wider telecom-security picture, review XMPP, SRTP, DTLS-SRTP, NAF, 3G and 6G — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

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