Open mpeyfuss opened 1 month ago
Looking at the spec more, eth_call is suggested which doesn't submit a tx to the blockchain. Was getting that confused with call in solidity! So there might be a standard path forward. Will think more on it.
I started making a fork/PR for this, but ran into some questions about the desire to refactor parts of this repo as I could see inclusion of this, plus other future standards, making the actual siwe.py
file much longer and complex. Instead, I made a quick update on our backend to account for ERC-6492 signatures and got it working. You can see the code sample below:
if signature.endswith(ERC6492_MAGIC_BYTES):
# decode data from the signature
factory_contract, factory_calldata, original_erc2171_signature = decode(
["address", "bytes", "bytes"], HexBytes(signature)
)
# create multicall contract
w3 = web3(str(msg.chain_id))
multicall_contract = w3.eth.contract(
address=w3.to_checksum_address(MULTICALL3_ADDRESS), abi=MULTICALL3_ABI
)
# generate EIP-1271 calldata
eip1271_contract = w3.eth.contract(
address=msg.address, abi=EIP1271_CONTRACT_ABI
)
message = encode_defunct(text=msg.prepare_message())
msg_hash = _hash_eip191_message(message)
tx = eip1271_contract.functions.isValidSignature(
msg_hash, original_erc2171_signature
).build_transaction()
# first eth_call
data = multicall_contract.functions.aggregate3(
[
(
w3.to_checksum_address(factory_contract), # target address
True, # allow failure
factory_calldata, # calldata
),
(
msg.address, # target address
True, # allow failure
HexBytes(tx["data"]), # calldata
),
]
).call()
sig_validation_successful = data[1][0]
magic_value = decode(["bytes4"], data[1][1])[0].hex()
# get signature repsonse
return sig_validation_successful and magic_value == EIP1271_MAGICVALUE
Questions:
abi
folder if we expect more to come in the future?verify_message
function. But for future proofing, could also see the use of a class being beneficial.
Wanted to open this issue as a place to discuss supporting ERC-6492. The ERC calls for the offchain verifier to essentially deploy the AA wallet and then verify the ERC-1271 signature after deploying.
This honestly feels like overkill to me, and surprises me that dapps should be responsible for deploying the contract for users.
Instead, I think we could work on recognizing the magic bytes32 value at the end of the signature to see the type of signature it is. Then, if the contract isn't deployed, could at least raise a better error message.
Let me know what you think! Happy to work on this in a PR!