Comparison of LTE Security and UMTS Security

LTE has inherited most of the Security architecture from UMTS, some enhancements have also been made. While there are lot of places to find the overview of the LTE Security architecture, a side-by-side comparison with UMTS will be helpful for peopple coming from UMTS background.

Security Elements

Authentication and Key Agreement	UMTS based on UMTS-AKA key derivation from the UMTS Authentication Quintuplet(RAND, CK, IK, RES, AUTN) LTE based on EPS-AKA key derivation from the UMTS Authentication Quintuplet(RAND, CK, IK, RES, AUTN) Key Derivation Functions use HMAC-SHA-256 K(ASME) computed from CK, IK, and AUTN, which is used for Integrity and Encryption keys
Integrity	UMTS Integrity protection mandatory for only few RRC messages. Integrity Protection Algorithm UIA1: Kasumi LTE Integrity Protection mandatory for all messages after (and including) Security Mode Command Integrity Protection Algorithm 128-EIA 1: based on SNOW 3G 128-EIA 2: based on AES-128
Encryption	UMTS Encryption Algorithm UEA0: no encryption. UEA1: Kasumi. LTE Encrption done independently at two levels NAS - for EMM and ESM messgaes PDCP-SRB(1 and 2) and DRB (1 .. 11) two SECURITY MODE COMMANDS for two sets of keys {K(NAS-enc), K(NAS-integrity)}   {K(RRC-enc), K(RRC-integrity)} Encryption Algorithm 128-EEA 0: No Encrption 128-EEA 1: based on SNOW 3G 128-EEA 2: based on AES-128