Account Abstraction (ERC-4337 / ERC-7579)

ERC-4337 introduces account abstraction without protocol changes. Users interact through smart contract wallets. Transactions are replaced by UserOperations processed by a Bundler and verified by an EntryPoint contract.

Architecture

User signs UserOperation
        |
        v
   Bundler (JSON-RPC)
        |
        v
   EntryPoint.handleOps()
        |
        +--> Wallet.validateUserOp()
        |         |
        |         +--> (optional) Paymaster.validatePaymasterUserOp()
        |
        +--> Wallet.execute(callData)

UserOperation Fields

Field	Description
Sender	The smart contract wallet address
Nonce	Anti-replay nonce managed by the EntryPoint
InitCode	Factory call to deploy the wallet (empty if already deployed)
CallData	The actual operation to execute
CallGasLimit	Gas for the main execution
VerificationGasLimit	Gas for the verification step
PreVerificationGas	Gas overhead for bundler compensation
MaxFeePerGas	EIP-1559 max fee
MaxPriorityFeePerGas	EIP-1559 priority fee
PaymasterAndData	Optional paymaster for sponsored gas
Signature	Signature for wallet verification

Building a UserOperation

using Nethereum.AccountAbstraction;

var userOp = new UserOperation
{
    Sender = "0xYourSmartWalletAddress",
    Nonce = 0,
    CallData = callData.ToHex(),
    CallGasLimit = 100000,
    VerificationGasLimit = 150000,
    PreVerificationGas = 21000,
    MaxFeePerGas = Web3.Convert.ToWei(30, UnitConversion.EthUnit.Gwei),
    MaxPriorityFeePerGas = Web3.Convert.ToWei(1, UnitConversion.EthUnit.Gwei)
};

Paymasters

Paymasters sponsor gas fees for UserOperations, enabling gasless transactions:

• Verifying Paymaster — validates an off-chain signature
• ERC-20 Paymaster — accepts tokens as gas payment
• Sponsoring Paymaster — fully sponsors gas

Nethereum Bundler

Nethereum includes its own bundler for development and application-specific chains:

dotnet add package Nethereum.AccountAbstraction.Bundler

Packages

Package	Description
Nethereum.AccountAbstraction	UserOperation creation, encoding, gas estimation
Nethereum.AccountAbstraction.Bundler	Full bundler with mempool and reputation
Nethereum.AccountAbstraction.Bundler.RpcServer	Bundler JSON-RPC server
Nethereum.AccountAbstraction.SimpleAccount	SimpleAccount factory interaction
Nethereum.AccountAbstraction.AppChain	AA integration for AppChain