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Cees van Wijk - How to preserve privacy on a blockchain?

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Blockchain Innovation Conference 2019 - #BIC19

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Cees van Wijk - How to preserve privacy on a blockchain?

  1. 1. How to preserve privacy on a blockchain? Blockchain Innovation Conference 2019 Cees van Wijk
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  3. 3. • Selective transaction sharing (Channels, private transactions etc.) • Intel SGX • Cryptography: • Homomorphic encryption • Ring signatures • Zero Knowledge Proofs 3 Privacy solutions
  4. 4. Quorum: only store a hash on the blockchain 4
  5. 5. Quorum: private tx 5
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  8. 8. • Notary service provides consensus on:  Transaction uniqueness  Transaction ordering  Transaction time-stamping  Transaction validity (optional) • Notary service has:  Plug-able consensus (RAFT, BFT-SMART)  High availability (crash failure tolerant cluster)  Byzantine Fault Tolerance (optional) 8 Corda notary service
  9. 9. Intel® Security Guard Extensions (Intel® SGX) Problem: Distributed verification of data means leaks private information Solution: Run verification in SGX enclave. SGX concerns: - Special hardware - Vendor lock-in - Key management - Side channels - Developer awareness 9
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  11. 11. Zero Knowledge Proofs
  12. 12. 12 ING & ZKP
  13. 13. Zero Knowledge Range Proof
  14. 14. • ING built a pre-compiled contract in Go-Ethereum that allows the entire network to verify that a secret number is in a known range. • For example validate a: • Proof of age • Proof of salary bandwidth • Proof of location • Proof that a payment is within limits Intro Provide commitment Create range- proof Validate Validate Validate Validate Validate Validate Validate
  15. 15. Zero Knowledge Proofs in Blockchain • ZCash (ZK-SNARKS to privately transact ZEC) • EY Nightfall ZK-SNARKS to privately transact tokens on Ethereum • Monero (ZK range-proofs) • AZTEC Confidential transaction protocol. • Hyperledger Fabric  Identity Mixer  Zero Knowledge Asset Transfer • Zether (JP Morgan) private transactions on public Ethereum • MimbleWimble private transactions on BitCoin
  16. 16. Questions?

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