Privacy-preserving techniques using zero knowledge proof in public Ethereum

2. Agenda ― Why Privacy is important in blockchain ? ― Theory and concept around Zero Knowledge proof ― Application of zk-Snarks in public Ethereum Blockchain ― Q & A 1 2 3 4

3. Importance of privacy 3 • It is an important human right • Allow people exercise unique moral choices • Enable our societies evolved around is healthy, and makes it more resilient and more humane

5. Once data is embedded in the blockchain it cannot be altered • • •

6. Do you think Bitcoin is still anonymous ? • Wallet address re-use, linking your transactions together into a single profile. • IP address re-use. • Combining inputs from multiple transactions, • Using mobile wallet, effectively revealing to a third party your full set of addresses.

7. Following a bitcoin transaction

11. In a Zero-knowledge (ZK) proof we have 2 participants: • Prover - Peggy • Verifier - Victor The prover wants to convince the verifier that a statement is true without leaking any extra information. E.g. the prover wants to convince the verifier that he has a secret without revealing it. Privacy-preserving techniques using zero knowledge proof in public Ethereum - Nov 3 - BAT3811 Zero-knowledge proof

13. Properties of ZK proofs: • Termination: the protocol finishes after a number of steps. • Completeness: if the statement is true then the verifier will be convinced of this at the end of the protocol. • Soundness: if the statement is false then it is unlikely that the verifier will be fooled. • Zero-knowledge: at the end of the protocol no sensitive information is leaked to the verifier. Privacy-preserving techniques using zero knowledge proof in public Ethereum - Nov 3 - BAT3813 Zero-knowledge proof

14. ©copyright 2017 zkSNARK Privacy-preserving techniques using zero knowledge proof in public Ethereum - Nov 3 - BAT38 14 Zero-knowledge Succinct Non-interactive ARguments of Knowledge Zero-knowledge: proving existence of a secret without revealing it Succinct: the communication volume is small Non-interactive: no interaction Arguments of Knowledge: proving that one knows the secret

15. ©copyright 2017 Non-Interactive Zero-knowledge Proof (NIZK) Privacy-preserving techniques using zero knowledge proof in public Ethereum - Nov 3 - BAT38 15 Peggy Victor Common Reference String Source: https://thenounproject.com Secret s Proof p Verify proof p

16. ©copyright 2017 Common Reference String (CRS) Privacy-preserving techniques using zero knowledge proof in public Ethereum - Nov 3 - BAT38 16 Initial parameters Trusted Setup Common Reference String Destroy the parameters !

17. ©copyright 2017 Pairing on elliptic curves Privacy-preserving techniques using zero knowledge proof in public Ethereum - Nov 3 - BAT38 17Source: https://desmos.com/calculator, https://en.wikipedia.org/wiki/Swiss_passport 𝐸 𝑎,𝑏 = 𝑂 ∪ { 𝑥, 𝑦 ; 𝑦2 = 𝑥3 + 𝑎𝑥 + 𝑏} RSA (bit length) EC (bit length) Security level 1248 160 80 2048 224 112 Pairing: mathematical tool used to instantiate a NIZK Elliptic curve: Efficiency Used by

18. Homomorphic encryption allows to perform operations on sensitive data while keeping it encrypted. Use case: secure cloud computing Privacy-preserving techniques using zero knowledge proof in public Ethereum - Nov 3 - BAT3818 𝐸𝑛𝑐 𝑚 + 𝐸𝑛𝑐 𝑛 = 𝐸𝑛𝑐(𝑚 + 𝑛) Homomorphic evaluation/ encryption

19. ©copyright ELCA 2017 19

22. ©copyright ELCA 2017 22 ? ? ? ? Reference: https://www.reddit.com/r/ethereum/comments/712idt/ethereum_testnet_just_verified_a_zcash_transaction/ TEST Contract Library: Pairing Pre-compiled EC operations

27. Innovations @ ELCA ELCA is working on innovation projects wich aims to cover the following domain(s) • Cloud Security and Searchable Encryption in the cloud • ChatBot and Natural Language processing • BigData • Blockchain

28. ©copyright 2017 ELCA expertise Digital & Business Transformation Complexity Reduction Modernization Automation & Standartisation Time to Market & Agility Alignement Business & IT Security … MARKET CHALLENGES PROJEKT ERFAHRUNG Consulting Software Engineering Technology Integration Application & Cloud Management BRANCHEN ERFAHRUNG Financial Services Health & Pension Public Administration Defense & Cybersecurity Transportation & Logistics Retail & Other Industries (ex. Intern. Org, Energy etc.) ANGESAGTE THEMEN IT Business Consulting ECM Enterprise Content Management CIM Customer Interaction Management Big Data & Analytics SaaS Service & Operations Architecture Privacy-preserving techniques using zero knowledge proof in public Ethereum - Nov 3 - BAT38 28

29. ©copyright 2017 Blockchain team Privacy-preserving techniques using zero knowledge proof in public Ethereum - Nov 3 - BAT38 29 – Blockchain – Team – Industry – Business expert Financial – Industry – Business expert Insurance – Industry – Business expert – Public sector – Industry – Business expert Healthcare Dedicated skilled Blockchain experts

31. Mr Nagib Aouini Mr Jorge Alvaradp Head of Cyber Security Lead Blockchain Architect Nagib.aouini@elca.ch Jorge.alvarado@elca.ch Tel : 021 613 2136 Tel : 021 613 2111 Confidential do not distribute 31 Dr Sonia Bogos Crypography Engineer Sonia.bogos@elca.ch Tel : 021 613 2111

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