ERC1077 - draft 0.01

IERC1077.sol

pragma solidity ^0.4.24;


contract IERC1077 {
    enum OperationType {CALL, DELEGATECALL, CREATE}

    event ExecutedSigned(bytes32 executionId, address from, uint nonce, bool success);

    function lastNonce() public view returns (uint nonce);

    function canExecute(
        address to,
        uint256 value,
        bytes data,
        uint nonce,
        uint gasPrice,
        address gasToken,
        uint gasLimit,
        OperationType operationType,
        bytes extraData,
        bytes signatures) public view returns (bool);

    function executeSigned(
        address to,
        uint256 value,
        bytes data,
        uint nonce,
        uint gasPrice,
        address gasToken,
        uint gasLimit,
        OperationType operationType,
        bytes extraData,
        bytes signatures) public returns (bytes32);
}

Hash calculation:

    function calculateMessageHash(
        address from,
        address to,
        uint256 value,
        bytes data,
        uint nonce,
        uint gasPrice,
        address gasToken,
        uint gasLimit,
        OperationType operationType,
        bytes extraData) public pure returns (bytes32)
    {
        return keccak256(
            abi.encodePacked(
                from,
                to,
                value,
                keccak256(data),
                nonce,
                gasPrice,
                gasToken,
                gasLimit,
                uint(operationType),
                keccak256(extraData)
        ));
    }

For identity example call would look like this:

calculateMessageHash(this, to, value, data, nonce, gasPrice, gasToken, gasLimit, operationType, extraData)

For generic relayer contract:

calculateMessageHash(key, to, value, data, nonce, gasPrice, gasToken, gasLimit, operationType, extraData)

Hi Marek, I can see that you are planning to be using only one nonce for everybody: lastNonce. We've identified it as a concurrency bottleneck, so are keeping the nonces separately per account: https://github.com/Tenzorum/personal-wallet-contracts/blob/master/contracts/PersonalWallet.sol#L24 which allows more parallelism.