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Security in Wireless Sensor Networks: Blocking and Tackling

This article discusses the importance of security in wireless sensor networks and provides strategies for achieving it, including encryption, authentication, and key distribution. It also highlights the challenges and misconceptions surrounding security in sensor networks.

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Security in Wireless Sensor Networks: Blocking and Tackling

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  1. Security in Wireless Sensor Networks:Blocking and Tackling K. Pister

  2. Security Goals Encryption Make sure that no one can see the data Integrity Avoid forged data/control Discard replayed packets Discard random, malformed, or corrupted packets Authentication Accept only trusted motes Join only trusted networks Commissioning and Binding Join only the right trusted network

  3. Conclusion • Building secure sensor networks is straightforward • Low power • Low (enough) computational complexity • Challenges • Perception: too hard, easy, not necessary • Commissioning and binding • Standards work is underway in the IETF

  4. I don’t need security Natanz Nuclear Facility, Iran (Wikipedia) • Lighting control • “We’re just doing lighting control” • Industrial rotation rate sensor • “It’s just an input” • Home temperature sensor • “Thieves target houses with <your company> thermostats set on ‘vacation’ ”

  5. I’ve got security! …. (not) REDACTED! • “Channel hopping is impossible to track” • “We have a secret algorithm” • “We keep the key secret” • HD DVD/Blueray 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0 • “Our keys are completely random. We use Linux rand() four times!”

  6. I need security • Streetline: Urban-scale parking sensor network • Single vendor, single installer, single data destination • Chevron: Industrial process sensors • Many vendors, many installers, many destinations • Consumers: Home automation • Many vendors, innumerate installers

  7. AES128 decrypt 128 Plaintext 128 Key Shared Key Cipher • AES Advanced Encryption Standard • Approved by NSA for US Top Secret docs • Software • 1ms, 10uJ • Hardware • 1us, 1nJ AES128 encrypt 128 128 Plaintext ciphertext 128 Key

  8. Shared-key Encryption & Integrity Authenticate payload & headers using AES128 CBC-MAC Generates “secure checksum” Message Integrity Code – 4B MIC Encrypt payload and MIC with AES128 CTR Append a 2 byte CRC checksum On reception Verify CRC Removes >99.999% of corrupted packets Decrypt payload, MIC Verify message integrity Packet A B ACK Authenticate integrity Encrypt in place Checksum

  9. Random Number Generators • Often the weak link in a well-designed system • rand(), time(), … • How do you find randomness in a digital system? • Thermal noise • RF • Sensor inputs • Oscillator frequency differences • NIST CTR_DRBG (deterministic random bit generator) • Accumulate 128 bits of entropy • Seed a DRBG • Apply AES with feedback to generator RN

  10. K K K K K KJ1 K KJ2 Key Distribution • Pre-shared keys • Single Shared • Shared join key  unique session keys • Unique join keys  unique session keys • Access Control List (ACL), Network ID • Allows segregation of networks • Powerful combination • Secure • Enables Binding • All shared-key (not PKI) K1 K2 K1 K2 K1 K2

  11. Use cases One supplier/installer One supplier, separate installers Multiple suppliers, one installer Multiple suppliers, multiple installers, multiple neighboring users ? ? ? • Building 2 networks • HVAC • Security • Fire • Tenant networks • Building 1 networks • HVAC • Security • Fire • Tenant networks New mote

  12. Cell-phone commissioning KJ1 • QR codes • Web databases • Cell localization • End state: • ACLs • Unique keys • Proper binding

  13. Standards • IEEE • 802.15.4e • IETF • CoAP • DTLS • 6TiSCH • OpenWSN.berkeley.edu

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