EPS-AKA

EPS Authentication and Key Agreement

Security

Introduced in Rel-8

Mutual authentication and key agreement protocol for LTE/EPS security.

Description

EPS Authentication and Key Agreement (EPS-AKA) is the security protocol used in LTE for mutual authentication between the UE and the network, and for deriving keys for encryption and integrity protection.

EPS-AKA is based on the UMTS AKA mechanism but enhanced with a key hierarchy supporting multiple protection levels (NAS, AS) and key separation between different network elements.

Purpose & Motivation

EPS-AKA was designed to:

- Provide mutual authentication (network and UE verify each other) - Generate key material for multiple security contexts - Support key separation between MME and eNodeB - Enable forward/backward security with key refresh

Key Features

  • Mutual authentication
  • Key derivation hierarchy
  • NAS security context
  • AS security context
  • Key refresh mechanisms

Evolution Across Releases

Rel-8Initial

Initial EPS-AKA with key hierarchy

Enhanced AKA for 256-bit keys

Defining Specifications

SpecificationTitle
EPS Security Architecture
Security Architecture