AKA (Authentication and Key Agreement)

Authentication and Key Agreement is the family of mutual-authentication protocols used in 3G UMTS, 4G LTE (EPS-AKA), and 5G (5G-AKA and EAP-AKA'). The USIM and the home network share a long-term key K. During each authentication, the home network sends a challenge that proves it knows K, and the USIM responds with a value that proves the same to the network, defeating false base station attacks possible against pure 2G GSM. The procedure also derives session keys for ciphering and integrity protection on the air interface and beyond.

Categories: Radio Access NetworkRoaming and InterconnectIdentity and Subscriber

AKA in context

The radio access network is the layer where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations, downgrade attacks and jamming, and defenses hinge on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

Roaming and interconnect are where two operators, often with an IPX or GRX carrier in between, exchange signaling and user-plane traffic. Trust boundaries here are the primary attack surface for location tracking, SMS interception and fraud, which is why GSMA now mandates SEPP with PRINS on 5G interconnect.

To place AKA in the wider telecom-security picture, review SUPI, AUSF, iSIM, IMEI, MNC and USIM.

Related terms

Related topic hubs

  • Diameter Attacks S6a IDR/PUR/CLR abuse, subscriber tracking, LTE signaling attacks.
  • Diameter Security 4G/LTE Diameter threats across IPX/roaming and DEA defenses.
  • Roaming Security IPX/GRX interconnect risk, home-routed vs local-breakout, SEPP.
  • 5G Security 5G SBA, SEPP, SUCI, 5G-AKA, N32 and service-based interface security.

More from the TelcoSec Glossary

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