1. RCDA: Recoverable Concealed Data Aggregation for Data Integrity in Wireless Sensor Networks Chien-Ming Chen, Yue-Hsun Lin, Ya-Ching Lin, Hung-Ming Sun IEEE Transactions on Parallel and Distributed Systems, Vol.23, No.4, April 2012 Presenter: 林顥桐 Date: 2012/11/19 1

2. Outline Introduction Encryption Scheme and Signature Scheme RCDA Scheme for Homogeneous WSN RCDA Scheme for Heterogeneous WSN Implementation and Comparisons Conclusion 2

3. Introduction The usage of aggregation functions is constrained The base station cannot verify the integrity and authenticity of each sensing data 3

4. Introduction RCDA – The base station can verify the integrity and authenticity of all sensing data – The base station can perform any aggregation functions on them 4

5. Encryption Scheme and Signature Scheme Encryption Scheme – Mykleton et al.’s Encryption Scheme Signature Scheme – Boneh et al.’s Signature Scheme 5

6. Encryption Scheme and Signature Scheme Mykleton et al.’s Encryption Scheme – Proposed a concealed data aggregation scheme based on the elliptic curve ELGamal(EC-EG) cryptosystem 6

7. Encryption Scheme and Signature Scheme Boneh et al.’s Signature Scheme – Proposed an aggregate signature scheme which merges a set of distinct signatures into one aggregated signature – Based on bilinear map 7

8. Outline Introduction Encryption Scheme and Signature Scheme RCDA Scheme for Homogeneous WSN RCDA Scheme for Heterogeneous WSN Implementation and Comparisons Conclusion 8

9. RCDA Scheme for Homogeneous WSN 9

10. Four procedures – Setup Base Station(BS) generates the key pairs – Encrypt-Sign Trigger while a sensor decides to send its sensing data to the cluster head(CH) – Aggregate Launched after the CH has gathered all ciphertext-signature pairs – Verify Receive the sum of ciphertext and signature from CH, BS can recover and verify each sensing data 10

11. RCDA Scheme for Homogeneous WSN Setup – (PSNi, RSNi ): For each sensor SNi, the BS generates (PSNi,RSNi) by KeyGen procedure(Boneh scheme) where PSNi = vi and RSNi = xi – (PBS, RBS): These keys are generated by KeyGen procedure(Mykletun scheme) where PBS ={Y, E, p, G, n} and RBS = t Privacy key, randomly selected from Zp Public key, where vi = xi*g Y = t*G, E is an elliptic curve over a finite Fp, p is a prime number, G is a generator on E, n is the order of E, t is a privacy key randomly from Fp 11

12. RCDA Scheme for Homogeneous WSN Setup – RSNi, PBS, H, are loaded to SNi for all i – BS keeps all public keys PSNi and its own RBS in privacy 12

13. RCDA Scheme for Homogeneous WSN Encrypt-Sign Boneh’s signature Mykleton’s Encrypt 13

14. RCDA Scheme for Homogeneous WSN Aggregate 14

15. RCDA Scheme for Homogeneous WSN Verify – 1) – 2) – 3) – 4) ? 15

16. Outline Introduction Encryption Scheme and Signature Scheme RCDA Scheme for Homogeneous WSN RCDA Scheme for Heterogeneous WSN Implementation and Comparisons Conclusion 16

17. RCDA Scheme for Heterogeneous WSN 17

18. RCDA Scheme for Heterogeneous WSN Five procedures – Setup Necessary secrets are loaded to each H-Sensor and L-Sensor – Intracluster Encrypt Involve when L-Sensor desire to send their sensing data to the corresponding H-Sensor – Intercluster Encrypt Each H-Sensor aggregates the received data and then encrypts and signs the aggregated result – Aggregate If an H-Sensor receives ciphertexts and signatures from other H- Sensor on its routing path, it activates the Aggregate procedure – Verify Ensure the authenticity and integrity of each aggregated result 18

19. RCDA Scheme for Heterogeneous WSN Setup – (RHi, PHi ): the BS generates this key pair for each H-Sensor according to KeyGen(Boneh’s scheme), i.e., RHi = xi and PHi = vi – (RBS, PBS): This key pair is generated by KeyGen(Mykletun’s scheme), i.e., PBS = {Y, E, p, G, n} and RBS = t Public key, where vi = xi*g Privacy key, randomly selected from Zp Y = t*G, E is an elliptic curve over a finite Fp, p is a prime number, G is a generator on E, n is the order of E, t is a privacy key randomly from Fp 19

20. RCDA Scheme for Heterogeneous WSN Setup – The BS loads PBS to all L-Sensors. Each H-Sensor is loaded its own key pair (PHi, RHi), PBS, and several necessary aggregation functions – Each L-Sensor is required to share a pairwise key with its cluster head 20

21. RCDA Scheme for Heterogeneous WSN Intracluster Encrypt – Ensure the establishment of a secure channel between L-Sensors and their H-Sensor 21

22. RCDA Scheme for Heterogeneous WSN Intercluster Encrypt – After collecting all sensing data from all cluster members, an H-Sensor performs the prefered aggregation function on these data as its result 22

23. RCDA Scheme for Heterogeneous WSN Intercluster Encrypt Boneh’s signature Mykleton’s Encrypt 23

24. RCDA Scheme for Heterogeneous WSN Aggregate – If H3 receives (c1, ) from H1 and (c2, ) from H2, H3 will execute this procedure to aggregate (c1, ), (c2, ) and its own (c3, ) as follows: – Finally, H3 sends ( ) to H5.Similarly, H5 can also aggregate (c4, ), (c5, ), and ( ) then get a new aggregated result ( ) to the BS 24

25. RCDA Scheme for Heterogeneous WSN Verify – 1) – 2) – 3) – 4) ? 25

26. Outline Introduction Encryption Scheme and Signature Scheme RCDA Scheme for Homogeneous WSN RCDA Scheme for Heterogeneous WSN Implementation and Comparisons Conclusion 26

27. Implementation and Comparisons Implementation 27

28. Implementation and Comparisons Comparisons – RCDA-HOMO has worst performance evaluation, because RCDA-HOMO provides better security 28

29. Conclusion The base station can securely recover all sensing data rather than aggregated results Integrate the aggregate signature scheme to ensure data authenticity and integrity in the design 29