General introduction into privacy and decentralization. High-level description of PETs (ZKP, MPC, Homomorphic encryption, Differential Privacy and others). The role of PETs and blockchain in the future world. How to enhance privacy for both transaction and personal data in decentralized world?

1. Privacy-enhancing
technologies and
blockchain
Dejan Radic,
CTO at DexStar

2. Intro
 Privacy is the ability to express yourself
selectively
 Freedom of choice
 Consent to use or reveal information
 PII – Personally Identifiable Information
 Blockchain – integrity protection
 What about confidentiality?

3. Blockchain
types

4. Privacy-
enhancing
technologies
Minimization of data sharing with low
influence on functionality
Security-Utility trade-off
Regulatory compliance
Terms and conditions
Audit and enforcement
Control over data transfers

5. Homomorphic
encryption
 Computing on encrypted data without first
decrypting it
 “Data in use” protection
 Enables secure processing outsourcing
 Computation overhead
 FHE – arbitrary circuits and gates
 TEE (Trusted Execution Environments)
 Employee expenses use case

6. Differential privacy
 Sharing aggregate information about dataset
 Is the individual info disclosed?
 Introduction of noise
 Reduced accuracy
 Suitable for larger datasets
 Privacy budget
 Synthetic datasets
 Employee salary example

7. Multi-party
computation
 Jointly compute function based
on private inputs
 Extracting aggregate
information from multiple
private datasets
 Communication overhead
 Average salary example

8. Zero-
knowledge
proofs
 Prover proves to verifier that he
knows X without disclosing X
 Pseudo-anonymity of public chains
 Anonymous transactions – not
revealing PII
 Authentication - password

9. Conclusion
 Ubiquitous and transparent public chains
 Outsourcing of computation
 Enforcement of data ownership
 Careful aggregate data publication
 Enhancement of anonymity
 New GDPR !?

10. Questions?

11. Thank you!