HMAC-SHA256 (Keyed-Hash Message Authentication Code with SHA-256)

Also known as: HMAC-SHA-256

HMAC-SHA256 (RFC 2104, FIPS 198-1) is a keyed message authentication code using SHA-256 as the underlying hash. It is used across telecom for integrity protection of authentication vectors, KDF constructions in 3GPP TS 33.220, JWT/JWS token signing on the 5G SBA, and TLS 1.2 fallback MACs.

Categories: Security ControlsProtocols and StandardsInternet and Routing

HMAC-SHA256 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 HMAC-SHA256 in the wider telecom-security picture, review 3G, A5/1, Digital Signature, IPv6, OSPF and SHA — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.