Secure and Safe Wireless Sensor and Actuator Networks for Industrial Automation Systems

1. An Engineering Approach for Secure and SafeWireless Sensor and Actuator Networks for Industrial Automation Systems Steffen Peter, Oliver Stecklina, Peter Langendörfer

2. Outline • Motivation • Introduction development flow • System analysis • Mapping process • Conclusions

3. Realflex project (2008-2010) Water works Biogas facility Roboter cell large distance,public networks Standards, existent architecture Small latency, dependability wireless architecture for industrial automation

4. Waterworks scenario

5. Today’s way of handling security • Shield network and define that it is secure not realistic in wireless networks • Enable “sort of miracle” security layer mostly not right solution • Patch security where a hole is assumed often not efficient all threads considered? • Proper design of security solutions expensive and time-consuming

6. Proposed development flow

7. System Analysis • Break it down • Find atomic flows of information  Data flow graph with dependencies • Analyze each processing step separately • What are the requirements for this step? • Ignore dependencies at this stage • Resolve dependencies • Requirements resolve over data flow

8. Example • Control pumps based on measured flow and pressure values • Uplink • Sensors on the field PLC • Wireless connection to the Ethernet access point • Downlink • PLCpumps • Wireless connection to the Ethernet access point • High integrity requirement U p l i n k D o w n l i n k sensor AP pump AP PLC

9. Security properties • Concealment / Secrecy • Integrity • Availability • Authentication • Authorization • Accountability • Non-Repudiation Security requirementsvector

10. Security Metric An algorithm belongs to class c if it resists all attacks from attacker groups smaller than c.  Requirement Vector = <(0…3)7>

11. Proposed development flow

12. Mapping Process

13. What to do if drawer is empty? • Find a solution from scratch • State of the art • Good solution • Not efficient • Look in neighborhood • Find close solutions • Analyze & solve the differences

14. Waterworks Example • Security: • Strong integrity • Environment: • open field, short range wireless (802.15.4) • One message every 30 seconds • Dependability: • node life time min. one month • 400mJ/operation -Information integrity >99.9999%  1/1 million

15. Waterworks Example (2) • Assumed no direct solution found • Neighborhood: wired environment • Security requirements fulfilled by protected environment • Information integrity realized with CRC we have no protected environment, but CRC is fine adapt dependencies (information integrity solved) • How to realize protected environment • Mapping tells us AES OFB is solution (message integrity due to pair-wise shared keys)  Test against other requirements: too high energy consumption

16. Waterworks Example (3) • Problem message overhead • 16 bit message + 20 bit CRC encrypted with 128 bit AES • Solution: take one AES key for 3 messages • 40 bit ciphertext • Still security of 128 bit AES OFB • Information integrity as in wired environment • Dependency requirements fulfilled

17. Conclusions • Suitable security and safety needs consideration of • Environment • Dependability requirements • Security requirements • Huge complexity, expensive development flow • Proposed semi-formal engineering methodology is a first answer • Requirements and potential solutions are cataloged as result of a formal analysis process • Allows reproducible problems and reusability of answers • Mapping process as efficient way to integrate applications • Fuzzy requirements (environment) still biggest challenge for a full automatic integration process

18. Thank You Questions? peter@ihp-microelectronics.com