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Account Abstraction (ERC-4337) — Key concepts

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4/8 — Account Abstraction (ERC-4337) — Key concepts

UserOperation flowUsers sign userOps; bundlers collect them; the EntryPoint validates and executes via wallet code.

UserOp cost (simplified)

cost = (preGas + callGas + verificationGas) × maxFeePerGas

Paymasters may cover cost but must be trusted/limited.

bytes32 userOpHash = keccak256(
    abi.encode(
        address(entryPoint),
        chainid,
        op.sender,
        op.nonce,
        keccak256(op.initCode),
        keccak256(op.callData),
        op.callGasLimit,
        op.verificationGasLimit,
        op.preVerificationGas,
        op.maxFeePerGas,
        op.maxPriorityFeePerGas,
        keccak256(op.paymasterAndData)
    )
);

ValidationThe wallet’s validateUserOp decides if a userOp is acceptable (signature, nonce, paymaster policy).

PaymastersCan sponsor gas conditionally; must guard against grief and DOS.

Key points

EntryPoint mediates all userOps;:Wallets implement validation and execution.
Nonce management and replay:Protection are on the wallet.
Paymasters:Set budgets, per-user rules, and revoke on abuse.
Bundler trust:Centralization risk; prefer reputable/open bundlers.
Signature schemes:EOA-like, multisig, or aggregated; gas vs security trade-offs.

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