Ethereum Protocol

Transcript

1. Ethereum Protocol Base on go-ethereum (v1.9.2)
2. Hello! I am Miya Chen, backend Enginner at AMIS Golang Developer Istanbul BFT consensus Wallet service Node management 2
3. ▷ Ethereum introduction ▷ Life cycle of an Ethereum transaction ▷ How mining works Agenda 3
4. Ethereum introduction 4
5. Ethereum ▷ Inspired by Bitcoin ▷ Provide a decentralized platform that runs customized code (smart contract) ▷ Launched on 30 July 2015 5
6. Design (Eth 1.x) ▷ Account based ▷ Account nonce ▷ Proof-of-Work ▷ Merkle Patricia tree/trie (MPT) ▷ Recursive Length Prefix (RLP) ▷ Gas / Gas Price ▷ EVM 6
7. Account ▷ There are two types of accounts ◦ Externally owned account (EOAs), controlled by private key ◦ Contract account, related to smart contract code 7
8. Externally owned account (EOAs) 0x81b7E08F65Bdf5648606c89998A9CC8164397647 0x15373557e8c20db2071cab70cacec54458d2bd8b 0x9138faCE3d0a58D744c529397c8978AcBBDaB5a0 EOA EOA EOA 8
9. Externally owned account (EOAs) 0x81b7E08F65Bdf5648606c89998A9CC8164397647 0x15373557e8c20db2071cab70cacec54458d2bd8b 0x9138faCE3d0a58D744c529397c8978AcBBDaB5a0 EOA to EOA A standard ETH transaction EOA EOA EOA 9
10. Contract account 0x81b7E08F65Bdf5648606c89998A9CC8164397647 0x15373557e8c20db2071cab70cacec54458d2bd8b 0x4CcA68A7811C48D4A98fC4471818c711Bb6CF0B7 EOA Contract Account EOA 0x9138faCE3d0a58D744c529397c8978AcBBDaB5a0 EOA 10
11. Contract account 0x81b7E08F65Bdf5648606c89998A9CC8164397647 0x15373557e8c20db2071cab70cacec54458d2bd8b 0x4CcA68A7811C48D4A98fC4471818c711Bb6CF0B7 EOA Contract Account EOA 0x9138faCE3d0a58D744c529397c8978AcBBDaB5a0 EOA Same address format for EOA and contract account 11
12. Contract account 0x81b7E08F65Bdf5648606c89998A9CC8164397647 0x15373557e8c20db2071cab70cacec54458d2bd8b 0x4CcA68A7811C48D4A98fC4471818c711Bb6CF0B7 EOA Contract Account EOA 0x9138faCE3d0a58D744c529397c8978AcBBDaB5a0 EOA ? 12
13. Contract account 0x81b7E08F65Bdf5648606c89998A9CC8164397647 0x15373557e8c20db2071cab70cacec54458d2bd8b 0x4CcA68A7811C48D4A98fC4471818c711Bb6CF0B7 EOA Contract Account EOA 0x9138faCE3d0a58D744c529397c8978AcBBDaB5a0 EOA 1. Contract account can’t send transaction by itself. 2. EOA initiates a transaction to trigger it. X 13
14. Contract account 0x81b7E08F65Bdf5648606c89998A9CC8164397647 0x4CcA68A7811C48D4A98fC4471818c711Bb6CF0B7 EOA Contract Account EOA EOA 1 1-1 1-2 14
15. Contract account 0x81b7E08F65Bdf5648606c89998A9CC8164397647 0x4CcA68A7811C48D4A98fC4471818c711Bb6CF0B7 EOA Contract Account EOA EOA Contract Account 1 1-1 1-2 1-2-1 15
16. Transaction ▷ Standard transaction (EOA to EOA) ▷ Contract transaction (EOA to contract account) ◦ Contract creation ◦ Contract invocation 16
17. Internal transaction Triggered by contract invocation 17
18. Transaction ▷ To change the state of blockchain ◦ Balance ◦ Storage 18
19. Life cycle of an Ethereum transaction 19
20. 1. Construct 2. Sign 3. Broadcast 4. Mined Life cycle of a transaction 20
21. 1. Construct 21
22. Address of the sender (EOA) Construct a transaction Address of the recipient (EOA or contract account) Amount of ether transferred Number of gas provided to execute this transaction Price used for each paid gas Compiled code of contract or the hash of the invoked method signature and encoded parameter https://etherscan.io/txsPending 22
23. What’s nonce ▷ Begin with zero ▷ Avoid replay attack ▷ Allow to overwrite your own pending transaction the use the same nonce 23
24. What’s gas ▷ Minimun gas for standard transaction: 21000 ▷ Block gas limit: ~8,000,000 ◦ Can pack maximum 380 txs in a block ▷ Tx fee = gas * gas price Tx1 gasLimit = 21000 Tx1 gasLimit = 21000 Tx3 gasLimit = 21000 ... Block gasLimit = 8,000,000 24
25. What’s gas https://ethgastable.info/ 25
26. 2. Sign 26
27. Sign transaction ▷ ECDSA Algorithm https://yos.io/2018/11/16/ethereum-signatures/ 27
28. 3. Broadcast 28
29. Broadcast transaction Node Miner 29
30. Broadcast transaction Node Miner 30
31. Broadcast transaction Node Miner A memory allocation called transaction pool, used to store TXs. Not each node has the same view. 31
32. Transaction pool ▷ Local vs Remote transactions ◦ Local: directly send to this node, will be kept always ◦ Remote: received from other nodes, might be dropped due to full tx pool 32
33. Transaction pool ▷ Pending vs Queued transactions ◦ Pending: ready to be processed and included in the block ◦ Queued: the transaction nonce is not in sequence 33
34. Transaction pool ▷ Can replace the transaction? Y ◦ Same sender ◦ Same nonce ◦ Higher gas price (10% by default) ◦ Transaction hash will be changed From: 0xABC.. To: 0xdef… Nonce: 100 Data: 0xffff… gas: 50000 gasPrice: 1 GWei From: 0xABC.. To: 0xdef… Nonce: 100 Data: 0xffff… gas: 50000 gasPrice: 2 GWei 34
35. 4. Mined 35
36. Pack transactions ▷ Consider the pending transactions ◦ Valid transaction ◦ Valid signature (v, r, s) ◦ Valid nonce ▷ How does a miner decide to pack TXs? ◦ Limited block size, gasUsed <= gasLimit ◦ Order by price and nonce ◦ Empty block is valid 36
37. Empty block is valid 37
38. Estimate gas price https://ethgasstation.info/index.php https://amberdata.io/dashboards/transactions 38
39. Transaction execution Sender Recipient Start End operattion gas used 50 operattion gas used 30 gas -50 gas -30 gas 200 Tx value: 300 wei gas limit: 200 gas price: 1wei Sender balance -500 Need to pay: 300 (value) + 200 * 1 (pre-paid tx fee) = 500 Recipient balance + 300 Miner Miner balance + 80 gas refund Sender balance + 120 39
40. Need to pay: 300 (value) + 200 * 1 (pre-paid tx fee) = 500 Transaction execution (execution failed) Sender Start End operattion gas used 50 operattion gas used 30 gas -50 gas -30 gas 200 Tx value: 300 wei gas limit: 200 gas price: 1wei Sender balance -500 Miner Miner balance + 80 ether transfer revert / gas refund Sender balance +300 + 120 revert state 40
41. Execution failed 41
42. Need to pay: 300 (value) + 200 * 1 (pre-paid tx fee) = 500 Transaction execution (Out of Gas) Sender Start End operattion gas used 150 operattion gas used 80 gas -150 gas -50 gas 200 Tx value: 300 wei gas limit: 200 gas price: 1wei Sender balance -500 Miner Miner balance + 200 Sender balance +300 revert state 42 ether transfer revert / no gas refund
43. Out of gas 43
44. Estimate gas limit ▷ Gas limit is to avoid the code runs into an infinite loop. ▷ Give large gas => enough balance ◦ Ether transfer: 21000 ◦ Token transfer depend on contract: 90000~200000 ▷ web3.eth.estimateGas ◦ Dry run transaction in EVM with current state 44
45. How mining works 45
46. Why need consensus? ▷ Consensus means that the nodes on the network agree on the same state of a blockchain ◦ Prevent double spend 97 98 99 100 100 100 46
47. How to reach a consensus? ▷ Pick block proposer ◦ Randomize => prevent single entity can control ◦ Block reward 47
48. PoW design principle ▷ Everyone can participate to solve problem (Decentralization) ▷ No one can control the right to write ledger (Randomize) ▷ Same probability The first one to get the number less than 3 can write blockchain ledger. 48
49. Hash function 49
50. Proof-of-Work ▷ Hard puzzle but easy to verify, adjustment difficulty (Hash function) 50
51. ▷ Follow the most difficult chain ▷ Reorg might be occurred ◦ Need the confirmation to ensure the transaction is finalized Fork choice rule Difficulty 2,992,833,186,612,935 Total Difficulty 7,381,509,111,578,673,834,542 Difficulty 3,081,843,657,645,896 Total Difficulty 7,394,502,708,643,356,684,070 51
52. Fast block time problem ▷ High number of stale blocks ▷ Frequently forks ▷ Centralization Bias ◦ Miner with higher hashpower alway wins the block reward ◦ Miner with lower hashpower continues to work on side chain 52
53. GHOST ▷ Greedy Heaviest Observed Subtree ◦ Includes uncle blocks ◦ Uncles get uncle reward ◦ Miner gets uncle inclusion reward ▷ Limited ◦ Only 2 uncle blocks in a block ◦ Uncles includable only up to 7 generations 1 2 3 4A 4 4B 5 block reward -> 5 7/8 block reward -> 4A 1/32 block reward -> 5 6 block reward -> 6 6/8 block reward -> 4B 1/32 block reward -> 6 7 53 https://github.com/ethereum/wiki/wiki/White-Paper#modified-ghost-implementation
54. http://ethviewer.live/ 54
55. “ Thank you 55 miyatlchen@gmail.com