1. Secure Pub-Sub: Blockchain-based Fair Payment with Reputation for Reliable Cyber Physical Systems
Source : IEEE Access, Vol. 6, pp , Jan. 2018
Authors : Yanqi Zhao, Yong Yu, Yannan Li, Qilin Mu, Bo Yang
Speaker : Fengyu Chiu
Date : 2018/10/1

2. Outline Introduction Preliminaries Proposed scheme Potential attacks
Security analysis
Performance analysis
Conclusions

3. Introduction Publisher Broker Subscriber Blockchain system
Subscription
Message
Match

4. Preliminaries –smart contract(1/2)
Coin
Ice cream
Store

5. Preliminaries – Reputation System(2/2)
Explicit rating(D)
Score: 0-1
Implicit rating(E)
Positive activity
Negative activity

6. Proposed scheme Event Make deposit and subscription Blockchain system
Payment
Topic
Publisher
Bitcoin and reputation
Notification
Subscriber
Sensors
Stream
Sensors
Stream

7. Proposed scheme - Setup
Security parameters: k
Public parameters
Choose prime p,q (q|p-1)
𝑔∈ 𝐺 𝑞
Random value 𝑘← {0,1} 𝑘
𝐻 : {0,1} ∗ → 𝐺 𝑞
𝐻 1 : {0,1} 𝑘 → 𝐺 𝑞
Key pair(Pk,SK)
𝑆𝑖𝑔 𝑝 (𝑚)

8. Proposed scheme - Publish
Reputation value: 𝐹 𝑅
Choose 𝑥∈ 𝑍 𝑞
Publisher
Computes 𝑦= 𝑔 𝑥
Blockchain system
𝐹 𝑅 , 𝑦 , Topic
Threshold: 𝜃
Value d’

9. Proposed scheme - Subscribe
Compute 𝑤=𝐻(Topic)
Choose 𝑟 0 ∈ 𝑍 𝑞
Subscriber
Blockchain system F
Compute 𝐹= {h, 𝑣 1 }
ℎ= 𝑔 𝑟 0 , 𝑣 1 = 𝑦 𝑟 0 𝑤
Value b

10. Proposed scheme - Match
Verify 𝐻 Topi c ′ = 𝑣 1 ℎ 𝑥
𝑘 1 ∈ {0,1} 𝑘
Publisher
𝑟 1 ∈ 𝑍 𝑞
Blockchain system
F, D, L
𝑘 1 ′ = 𝐻 1 (𝑘, 𝑘 1 )
𝑧 1 = 𝑔 𝑟 1
𝑧 2 = ℎ 𝑟 1 ∙ 𝑘 1 ′
Symmetric encryption 𝐶=𝐸𝑛𝑐( 𝑘 1 ,𝑀)
D : { 𝑧 1 , 𝑧 2 ,𝐶}
L = H(F)

11. Proposed scheme - Verification and Payment
𝐻 1 : {0,1} 𝑘 → 𝐺 𝑞
𝑘 𝑠 ′ = 𝐻 1 −1 𝑘, 𝑘 𝑠 = 𝐻 1 −1 𝑘, 𝑘 1 ′ = 𝑘 1
Verification
𝑘 𝑠 = 𝑧 2 𝑧 1 − 𝑟 0 = 𝑘 1 ′
𝑘 𝑠 ′ = 𝐻 1 −1 𝑘, 𝑘 𝑠
𝑀=Dec( 𝑘 𝑠 ′ ,𝐶)
Publisher
Subscriber
𝐹 𝑅 , L, d’
Blockchain system
𝐹 𝑅 , L, d’
Payment
𝐹 𝑅 , L
Value d’
Redeem
Value b

12. Proposed scheme - Others
Publisher
Redeem value d’
Malicious subscriber
Value b
Malicious publisher
Value d’

13. Potential attacks Denial of service attack(Dos attack)
Unfair attack/Collusion attack
Standard deviation
Re−Entry attack
IP address

14. Security analysis Confidentiality Symmetric encryption Completeness
Fairness
Anonymous

15. Performance analysis(1/2)
[10] M. A. Tariq, B. Koldehofe, A. Altaweel, and K. Rothermel, “Providingbasic security mechanisms in broker-less publish/subscribe systems,” Proc. 4th ACM Int. Conf. Distrib. Event-Based Syst., pp. 3849, Jul
[8] Y. Baseri, B. Takhaei and J. Mohajeri, “Secure untraceable offline electronic cash system,” Scientia Iranica, 20(3), pp. 637–646, 2013.
[11] M. A. Tariq, B. Koldehofe, and K. Rothermel, “Securing broker-less publish/subscribe systems using identity-based encryption,” IEEE Trans. Parallel Distrib. Syst., vol. 25, no. 2, pp , Feb
[41] H. Huang, X. Chen, Q. Wu, X. Huang, and J. Shen, ``Bitcoin-based fair payments for outsourcing computations of fog devices,'' Future Generat. Comput. Syst., vol. 78, pp , Jan [Online]. Available:

16. Performance analysis(2/2)
123

17. Conclusions
Fairness payment
Confidentiality of data