Network Access Security in Mobile 4G LTE. Huang Zheng Xiong Jiaxi An Sihua

Transcription

1 Network Access Security in Mobile 4G LTE Huang Zheng Xiong Jiaxi An Sihua

2 Outline Mobile Evolution About LTE Overview of LTE System LTE Network Access Security Conclusion

3 Mobile Evolution Improvements in mobile communication technology during the last two decades The Mobile Broadband is as important as Internet

4 Long Term Evolution What is LTE? The latest standard in the mobile network technology tree A project of 3GPP & mainly built on 3GPP cellular systems family May be referred as E-UTRA & E-UTRAN Has advanced new radio interface Circuit switched networks all-ip networks Broadband connectivity on the move 100Mbps(DL), 50Mbps(UL), ~10 ms Latency

5 2G/3G to LTE

6 S1 & X2

7 LTE key features High Spectral Efficiency more customers, less costs Co-existence with other standards Flexible radio planning (cell size of 5km 30/100km) Reduced Latency less RTT (multi-player gaming, audio/video conferencing) Reduced costs for operators (OPEX & CAPEX) Increased data rates via enhanced air interface (OFDMA,SC- FDMA,MIMO) All-IP environment SAE or EPC

8 Overview of 3GPP LTE/SAE System

9 Evolving Security Architecture GSM Ciphering Radio Controller Handset Authentication Core Network GPRS 3G SAE/LTE Handset Authentication + Ciphering Mutual Authentication Ciphering + Signalling integrity Ciphering + Radio signalling integrity Mutual Authentication Core Signalling integrity Optional IPSec

10 SAE/LTE Implications on Security Security implications due to Flat architecture: RAN protocols terminate in enb Interworking with legacy and non-3gpp networks Allowing enb placement in untrusted locations Extended Authentication and Key Agreement More complex key hierarchy More complex interworking security Additional security for enb (compared to NB/BTS/RNC)

11 Security in the LTE-SAE Network ME = Mobile Equipment USIM = Universal Subscriber Identity Module AN = Access Network HE = Home Environment SN = Serving Network (I) Network access security: secure access to services, protect against attacks on (radio) access links (II) Network domain security: enable nodes to securely exchange signaling data & user data (between AN/SN and within AN, protect against attacks wireless network (III) User domain security: secure access to mobile stations (IV) Application domain security: enable applications in the user and in the provider domain to securely exchange messages

12 Network Access Security User identity (and location) confidentiality Entity authentication Confidentiality Data integrity Mobile equipment identification

13 Security Functions Authentication and key agreement UMTS AKA re-used for SAE SIM access to LTE is explicitly excluded (USIM R99 onwards allowed) Signalling protection For core network (NAS) signalling, integrity and confidentiality protection terminates in MME (Mobility Management Entity) For radio network (RRC) signalling, integrity and confidentiality protection terminates in enodeb User plane protection Encryption terminates in enodeb Separate protection in on network interfaces

14 Authentication and Key Agreement HSS generates authn data and provides it to MME Challenge-response authn and key agreement between MME and UE

15 Confidentiality and Integrity of Signaling RRC signaling between UE and E-UTRAN NAS signaling between UE and MME S1 interface signaling (optional) protection not UE-specific protection is not UE-specific optional to use

16 User Plane Confidentiality S1-U (optional) protection not UE-specific, based on IPsec (Enhanced) network domain security mechanisms (based on IPsec) Optional to use Integrity not protected performance limited protection for application layer

17 Crypto-Algortitms Two sets of algorithms 128-EEA1 and 128-EIA1 (identical to UEA2 and UIA2 for UMTS) AES and SNOW 3G chosen as basis Principle: should be as different from each other as possible Rel-99 USIM is sufficient Key length 128 bits included possibility to add 256-bit keys Deeper key hierarchy than UMTS

18 Key Hierarchy in LTE/SAE

19 Summary and Conclusions New architecture and business environment require enhancements to LTE security Radio interface user plane security terminates in base station site Cryptographic separation of keys Different security mechanisms in many inter-working cases with both 3GPP and non-3gpp access networks

20 Thank you!