TETRA @ Your Service

1. TETRA @ Your Service The Security mechanisms designed into TETRA – a refresher How do you ensure the solution is secure? “Jeppe” Jepsen Motorola

2. Threats to communication and the threats to security • Message related threats • interception, eavesdropping, masquerading, replay, manipulation of data • User related threats • traffic analysis, observability of user behaviour • System related threats • denial of service, jamming, unauthorized use of resources

3. Why TetraSchengenPolice Corporation

4. Key security features of TETRA • Authentication • Air Interface encryption • End to end Encryption

5. Authentication Authentication Centre • Authentication provides proof identity of all radio’s attempting use of the network. • A session key system from a central authentication centre allows key storage • Secret key need never be exposed • Authentication process derives air interface key (TETRA standard) Session keys Switch 1 Switch 2 Challenge and response from Switch MS Authentication

6. What is Air Interface Encryption? • First level encryption used to protect information over the Air Interface • Typically software implementation • AIE is System Wide • 3 different Classes • Class 1 • No Encryption, can include Authentication • Class 2 • Static Cipher Key Encryption, can include Authentication • Class 3 • Dynamic Cipher Key Encryption • Requires Authentication

7. The air interface was considered vulnerable. • Air Interface encryption was designed to make the air interface as secure as the fixed line connection Fixed Links Air Interface Encryption Clear Air Interface! TETRA Air Interface Encryption • Network fixed links are considered difficult to intercept. Operational Information

8. Dimetra Air Interface Encryption • Full Implementation of AIE • Authentication • Static Cipher Key • Common Cipher Key • Derived Cipher Key • Group Cipher Key • Modified Group Cipher Key • TEA 1, 2, 3 and TEA 4 algorithms • Authentication Centre • Key Management Centre • Key Loader for key distribution

9. MS1 DCK1 A MS2 DCK2 Infrastructure Dispatcher 1 DCK3 MS3 C B MGCKB MGCKC SCK MS9 MS4 MS8 MS5 Group 1 SCK MS6 MS7 Air Interface Encryption - the Keys Clear audio SCK, CCK and MGCK controlled by System Owner DCK Generated through Authentication Process

10. The importance of Air Interface encryption • Many threats other than eavesdropping • traffic analysis, observance of user behaviour • Strong authentication • AI protects control channel messages as well as voice and data payloads • encrypted registration protects ITSIs • End to end encryption if used alone is much weaker (it only protects the payload)

11. Standardised end to end in TETRA • Many organisations want their own algorithm • Confidence in strength • Better control over distribution • ETSI Project TETRA provides standardised support for end to end Encryption • To give TETRA standard alternative to proprietary offerings and technologies • TETRA MoU – Security and fraud Protection Group • Provides detailed recommendation on how to implement end to end encryption in TETRA    • Provides sample implementation using IDEA and AES128

12. Confidentiality Solutions – Air interface encryption • Should provide security equivalent to the fixed network • There are several issues of trust here • Do I trust that the AIE has been implemented properly • Do I trust the way that the network (or radio) stores keys • Do I trust the fixed network itself • A strong AIE implementation and an evaluated network can provide essential protection of information • An untested implementation and network may need reinforcing, for example with end to end encryption

13. Processes for accreditation • HANDLING PROCESSES • Set Up Issues • Getting from the Organization Chart to planning secure communications • Getting the system setup properly • Introducing new units and new secure communications groups • Key Material Delivery Issues • Getting the right encryption keys into the right radio • Ensuring the security of key storage and distribution • Accomplishing fast, efficient periodic rekeying • Verifying readiness to communicate • Avoiding interruptions of service • Security Management Issues • Dealing with compromised or lost units • Integrating with key material distribution process • Audit control, event archival, and maintaining rekeying history • Controlling access to security management functions KEYLOAD PROCESS • Protect National Security • Key load in country of use • Key load by security cleared nationals • Remove keys from radios sent abroad for repair • Key Load encrypted • keys cannot be read while being programmed • Customer Friendly • Keys can be programmed “In Vehicle” (& away from secure area) • Accurate • Audit logs of key distribution • “In Country” Key Generation • Secure Storage • CONNECTION PROCESSES • Connected networks • Security levels • Assurance requirements • Barriers • Own operating procedures • Virus protection • PERSONNEL PROCESSES • Ensure personnel are adequately cleared and trained • Where do they live • Criminal records • Experience in secure environment • Signed relevant agreements • Procedures for security breaches • REPORTING PROCESSES • Stolen radio reporting • Radio disabling procedures • Radio key erasure procedures • Intrusion detection reporting and response • Attack detection and correlation …..and more.

14. Assuring your security solution • Evaluation of solutions should be by a trusted independent body • Who? • Manufacturer? • Vested interest • Blindness to own weaknesses • End user • Do you have the skills?

15. Assuring your security solution • Government • Closest to own requirements and solutions • Sets the rules as well as tests them • Can lead to changing requirements as threats change • Third party evaluation house • Need to ensure you can trust them • Proven capability, references, experience in the field • Can have more bandwidth than government • Typically evaluation of crypto solutions is undertaken by a government body, assurance of the rest of the network by a reputable company, but the accreditator has to be a member of the end user organisation • Who else can be allowed to accept the risks?

16. And if you don’t have this capability? • Look for suppliers with track record and reputation • Look for validations of an equivalent solution elsewhere • Get some expert help on processes and procedures

17. Finally….cost • Evaluation can be extremely expensive – how to get best value for money? • Stable requirements • Understanding the context • Strong implementations • It can be cheaper to spend more putting in a strong solution than the evaluation cost of a cheap solution! Proof for small lock Proof for large lock

18. Does the government get good value? • How much do you value national security? • Do you understand the cost of security measures vs the cost of compromise? • Can you afford to risk doing nothing?

19. EVALUATED Standard Essentials of a secure system • A strong standard • A good implementation • Experienced supplier • Trusted evaluation

20. University Cryptanalysis Department Example accreditation issue • Your microwave link passes over a university with an MSc course in security Switch Site

21. Security and Fraud Prevention Group – a TETRA MoU body • REC 02 – Framework for End to end Encryption and key Mangement • REC 03 – TETRA Threat Analysis • REC 04 – Implementation and use of TETRA Security Features

22. Thank You ? www.tetramou.comwww.etsi.orgwww.motorola.com/tetraJeppe.Jepsen@Motorola.com