A night of consensus

How do we think about Consensus on Celo

Transcript

1. A Night of Consensus, July 22nd 2019 Nam Chu Hoai | @nambrot | @CeloHQ | celo.org
2. Celo is an open platform that makes financial tools accessible to anyone with a mobile phone.
3. • PoS blockchain with EVM • Stable coin platform, backed by diversified reserve • Lightweight, decentralized identity protocol • Decentralized Eigentrust-based reputation • Full on-chain governance OPEN PLATFORM APPLICATIONS e.g. Celo Wallet “Whatsapp for Money” Mobile-First Approach
4. Build a monetary system that creates the conditions for prosperity - for everyone. Celo’s Mission
5. 50 Contributors + 20 Languages Spoken 6.4k Community Members 120 User Research Interviews + 64 Community Events 80k Lines of Code
6. “Life is not good. It is not bad. It’s just living — there is no other way.” Kaburu, Congolese Refugee in Tanzania
7. Transaction fees Kaburu, Congolese Refugee in Tanzania
8. ERC20 Compatible interface GasToken { function transfer(address, uint256) external returns (bool); function approve(address, uint256) external returns (bool); function transferFrom(address, address, uint256) external returns (bool); function totalSupply() external view returns (uint256); function balanceOf(address) external view returns (uint256); function allowance(address, address) external view returns (uint256); function debitFrom(address, uint256) external; function creditTo(address, uint256) external; }
9. Consensus on Celo
10. Proof of Work
11. • PBFT Based • PREPREPARE/PREPARE/COMMIT • Locking instead of roundchange certificates • Gossip for consensus messages Istanbul BFT
12. IBFT modifications • PBFT-style round change certificates • Removal of Gossiping • Sentry setup
14. Fast Sync for Ultra-light Clients LES Compatible BLS Signature Aggregation* ZK-SNARKs* Coming soon*
15. Mapping Phone Numbers To Wallet Addresses
16. Mapping Phone Numbers To Wallet Addresses
17. Permissionless BFT?
18. BFTree
19. Validator Tree (Global State) Older / More Trusted Newer / Less Trusted Validator 1 B 1 , PK 1 Validator 2 B 2 , PK 2 Validator 3 B 3 , PK 3 Validator 4 B 4 , PK 4 Virtual Validator 1-2 B 1-2 , PK 1-2 Virtual Validator 3-4 B 3-4 , PK 3-4 Virtual Validator 1-4 B 1-4 , PK 1-4 B N = Total stake for subtree. Used as a node weight in BFT algorithm PK N = Public key for multisig requiring signature of entire subtree to validate
20. Example Tree Rebuilding 1 1 1 1 1 1 1 1 2 2 2 2 4 4 8 1 1 1 1 1 1 1 1 2 2 2 2 4 4 8 16 Red: disagreement / offline Labels: total stake size, same for all nodes for simplicity
21. Example Tree Rebuilding 1 1 1 1 1 1 1 1 2 2 2 2 4 4 8 1 1 1 1 1 1 1 2 2 1) Disband all trees without unanimous consent 1
22. Example Tree Rebuilding 1 1 1 1 1 1 1 1 2 2 2 2 4 4 8 1 1 1 1 1 1 1 2 2 1) Disband all trees without unanimous consent 2) Run BFT with virtual nodes Weighted BFT Algorithm 1
23. Example Tree Rebuilding 1 1 1 1 1 1 1 1 2 2 2 2 4 4 8 1 1 1 1 1 1 1 2 2 1) Disband all trees without unanimous consent 2) Run BFT with virtual nodes Weighted BFT Algorithm 1
24. Example Tree Rebuilding 1 1 1 1 1 1 1 1 2 2 2 2 4 4 8 1 1 1 1 1 1 1 2 2 1) Disband all trees without unanimous consent 2) Run BFT with virtual nodes 3) Move all misbehaving nodes to the right side 1
25. Example Tree Rebuilding 1 1 1 1 1 1 1 1 2 2 2 2 4 4 8 1 1 1 1 1 1 1 2 2 1) Disband all trees without unanimous consent 2) Run BFT with virtual nodes 3) Move all misbehaving nodes to the right side (order them by reverse stake) 1
26. Example Tree Rebuilding 1 1 1 1 1 1 1 1 2 2 2 2 4 4 8 1 1 1 1 1 1 1 2 2 1) Disband all trees without unanimous consent 2) Run BFT with virtual nodes 3) Move all misbehaving nodes to the right side (order them by reverse stake) 4) Construct a new tree in this order 1 2 2 4 4 8 16
27. Develop Contribute github.com/celo-org Run a Node Validator or Full Node docs.celo.org Fellowship Propose a project Events Host a meetup Jobs Join the team Get Involved
28. Thanks, we value your time A Night of Consensus, July 22nd 2019 Nam Chu Hoai | @nambrot | @CeloHQ