ETH Taipei 2023 Account Abstraction Workshop

ERC-4337 account abstraction workshop for ETH Taipei 2023.

Slides

Environment

Foundry (installation)
Node.js >= v12 (installation)

Setup

$ forge install
$ npm install

Use npm to run test:VoidAccount script to confirm project is ready:

$ npm run test:VoidAccount

# ...
Running 1 test for test/VoidAccount.t.sol:VoidAccountTest
[PASS] testExecuteUserOp() (gas: 113868)

Folder Layout

contracts: It contains all the contracts you need to implement in this workshop.
test: It contains tests for each contract in the contracts folder. Tests will fail by default at the beginning, and you have to implement contracts in contracts folder to make all tests passed. You should not modify files in this folder.

Tasks

1. DepositAccount

Account must have enough ETH balance on EntryPoint to pay the gas fee for executing a user operation. Please implement contracts/DepositAccount.sol to make test/DepositAccount.t.sol passed.

Run the following command to verify:

$ npm run test:DepositAccount

# Before
# ...
Encountered 1 failing test in test/DepositAccount.t.sol:DepositAccountTest
[FAIL. Reason: FailedOp(0, AA21 didn\'t pay prefund)] testExecuteUserOp() (gas: 32753)

# After
# ...
Running 1 test for test/DepositAccount.t.sol:DepositAccountTest
[PASS] testExecuteUserOp() (gas: 115405)

2. SignatureAccount

Account should verify signature on user operation is signed by owner. Please implement contracts/SignatureAccount.sol to make test/SignatureAccount.t.sol passed.

Run the following command to verify:

$ npm run test:SignatureAccount

# Before
# ...
Encountered 1 failing test in test/SignatureAccount.t.sol:SignatureAccountTest
[FAIL. Reason: Call did not revert as expected] testCannotExecuteUserOpSignedByOther() (gas: 88380)

# After
# ...
Running 2 tests for test/SignatureAccount.t.sol:SignatureAccountTest
[PASS] testCannotExecuteUserOpByOther() (gas: 44437)
[PASS] testExecuteUserOp() (gas: 98404)

3. InitCode

With account factory, we can deploy account along with the first user operation by providing deployment info in initCode field. Please implement contracts/InitCode.sol to make test/InitCode.t.sol passed.

$ npm run test:InitCode

# Before
# ...
Encountered 1 failing test in test/InitCode.t.sol:InitCodeTest
[FAIL. Reason: EvmError: Revert] testInitCode() (gas: 75414)

# After
# ...
Running 1 test for test/InitCode.t.sol:InitCodeTest
[PASS] testInitCode() (gas: 327206)

Bundler Demo

(prerequisite: environment needs python3 installed to run below script)

For this demo, we will interact with three pre-deployed 4337 accounts on Sepolia testnet:

0xbF975Ba9ad5c242730435c9C133AedAE4B942dfa (Account accessing BANNED OPCODE)
0x1046E6729cb6926a76364387fA24aA8551527AFC (Account accessing invalid Storage Slot)
0xcbd1f8E195007Fbf0400c644E3593CB3afE6930E (Account that does not violate anything)

Interacting with Account using BANNED OPCODE

The bundler should reject our request since we are calling a banned opcode in this account.

$ export PRIVATE_KEY=$RANDOM
$ export ACCOUNT_ADDR=0xbF975Ba9ad5c242730435c9C133AedAE4B942dfa
$ export RPC_URL=${SEPOLIA_ENDPOINT}
$ export BUNDLER_URL=${BUNDLER_ENDPOINT}

# Run command at project root:
$ ./bash/payload_builder.sh -a

# Expected output:
#
# Generating userOperation...
# Building userOp http payload for bundler...
#
# ------------Result Payload--------------
#
# {
#   "jsonrpc": "2.0",
#   "id": 1,
#   "method": "eth_sendUserOperation",
#   "params": [
#    ...
#     },
#     "0x0576a174D229E3cFA37253523E645A78A0C91B57"
#   ]
# }
#
# ------------Sending payload to bundler--------------
#
# {
#   "error": {
#     "code": -32502,
#     "data": "account uses banned opcode: SELFBALANCE",
#     "message": "account uses banned opcode: SELFBALANCE"
#   },
#   "id": 1,
#   "jsonrpc": "2.0"
# }

Interacting with Account accessing invalid Storage Slot

The bundler should reject our request since we are not accessing the valid storage slot.

$ export PRIVATE_KEY=$RANDOM
$ export ACCOUNT_ADDR=0x1046E6729cb6926a76364387fA24aA8551527AFC
$ export RPC_URL=${SEPOLIA_ENDPOINT}
$ export BUNDLER_URL=${BUNDLER_ENDPOINT}

# Run command at project root:
$ ./bash/payload_builder.sh -a

# Expected output:
#
# Generating userOperation...
# Building userOp http payload for bundler...
#
# ------------Result Payload--------------
#
# {
#   "jsonrpc": "2.0",
#   "id": 1,
#   "method": "eth_sendUserOperation",
#   "params": [
#    ...
#     },
#     "0x0576a174D229E3cFA37253523E645A78A0C91B57"
#   ]
# }
#
# ------------Sending payload to bundler--------------
#
# {
#   "error": {
#     "code": -32502,
#     "data": "account has forbidden read to 0x87224F6D41DF6044ddd30a87bBdEeBc8c8CAc4f0 slot 4dbb180290de92ae0711e87110c97f6daba9f11cdfc121096b461bdc56cfe39f",
#     "message": "account has forbidden read to 0x87224F6D41DF6044ddd30a87bBdEeBc8c8CAc4f0 slot 4dbb180290de92ae0711e87110c97f6daba9f11cdfc121096b461bdc56cfe39f"
#   },
#   "id": 1,
#   "jsonrpc": "2.0"
# }

Interacting with a standard valid Account

The bundler should accept our request since this account doesn't violate any rule. Bundler will return the userOpHash if request accepted.

$ export PRIVATE_KEY=$RANDOM
$ export ACCOUNT_ADDR=0xcbd1f8E195007Fbf0400c644E3593CB3afE6930E
$ export RPC_URL=${SEPOLIA_ENDPOINT}
$ export BUNDLER_URL=${BUNDLER_ENDPOINT}

# Run command at project root:
$ ./bash/payload_builder.sh -a
# Expected output:
#
#
# Generating userOperation...
# Building userOp http payload for bundler...
#
# ------------Result Payload--------------
#
# {"jsonrpc": "2.0", "id": 1, "method":eth_sendUserOperation
# ...}
#
#
# {
#   "jsonrpc": "2.0",
#   "id": 1,
#   "method": "eth_sendUserOperation",
#   "params": [
#    ...
#     },
#     "0x0576a174D229E3cFA37253523E645A78A0C91B57"
#   ]
# }
#
# ------------Sending payload to bundler--------------
#
# {
#   "id": 1,
#   "jsonrpc": "2.0",
#   "result": "0x744a21e2b6eaaa59c9481c9b3d9f99e0968dffece71df3dfb55bad4a8d4353cf"
# }

Deploy a standard 4337 Account on Sepolia

The following script will deploy a SimpleAccountFactory and use the factory to create a SimpleAccount(SimpleAccountFactory & SimpleAccount are both from officical sample code).

# Make sure account owner address is under your control,
# you will need its private key to sign userOp
$ export ACCOUNT_OWNER_ADDR=${OWNER_ADDRESS_OF_ACCOUNT}
$ export PRIVATE_KEY=${PRIVATE_KEY_OF_DEPLOYER}
$ export RPC_URL=${SEPOLIA_ENDPOINT}

# Run command at project root:
$ forge script ./script/bundler/DeploySimpleAccount.s.sol --tc Deploy --rpc-url $RPC_URL --broadcast

FoodChain1028/ethtaipei2023-aa-workshop