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# ERC 4337
# Account Abstraction (AA)

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# Ethereum Account

- <span class="medium">Externally-owned account (EOA): 由私鑰控制的個人錢包，例如 MetaMask</span>
- <span class="medium">Contract Account (CA): 由智能合約控制的錢包</span>

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# Ethereum Account

<span class="medium">交易Transaction只能有EOA發起，並且付Gas</span>

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## Classic Account Security

- Authentication
-- ECDSA

- Replay Protection
-- Sequencial nonce

- Payment (Dos protection)
-- Account Payment (Gas)

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### Account Abstraction

- Authentication
-- <span class="medium">Different schemes (ECDSA、BLS、Quantum-resistant)</span>
-- <span class="medium">Change signer</span>
-- <span class="medium">Multiple signers</span>
-- <span class="medium">Recovery</span>
- Replay Protection
-- <span class="medium">Sequencial nonce</span>
-- <span class="medium">Parellel, multi-dimentional</span>
- Payment
-- <span class="medium">Account Payment (Gas)</span>
-- <span class="medium">Paymasters</span>

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# 功能特性

- Social Recovery
- Multisig
- Bundled transactions
-- save time & gas fee
- Preapproved transactions
- Sponsored transactions courtesy of Paymasters
-- Any token gas
-- 3rd party payment in fiat
- Subscription-based models
- Multi-factor authentication

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# AA history

- <span class="medium">EIP-86: 引入account contracts作為「轉發合約」，任何人都可以從入口地址轉發交易</span>
- <span class="medium">EIP-1014: 預測部署合約地址，發揮合約錢包CA作用，確保CA在所有EVM鏈上相同</span>
- <span class="medium">EIP-2938: 創建全新的操作密碼進行AA交易，因協議變更過大而被放棄</span>
- <span class="medium">EIP-3074: 創建兩個全新的OpCode，一起使用時允許CA代表EOA發送交易，但面臨安全風險未被實施</span>
- <span class="medium">EIP-4337：不修改共識層，引入了User Operations，並可以Bundler打包上鏈</span>

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# AA Components-1

- UserOperation - a new transaction type

- Wallet (Account)
-- Wallet Contract - a contract representing a user account
-- Wallet Deployer - a contract (singleton) that creates a wallet -- contract
-- Wallet Software - UX to sign and send the UserOp to the nodes.

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# AA Components-2

- Paymasters - a contract that can pay for transaction instead of wallet itself

- Bundlers - a network nodes that added support for AA
- EntryPoint - execute UserOps as standard transactions

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### Off-chain architecture


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### on-chain flow


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## Reference

- https://beincrypto.com/learn/erc-4337/
- https://bit.ly/aawallet1
- https://foresightnews.pro/article/detail/27311
- https://www.panewslab.com/zh_hk/articledetails/v2ye3h9dm9hu.html
- https://beincrypto.com/learn/erc-4337/

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# Q & A

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### 運行流程


- User Operations
- Bundler 打包
- 運行交易