Official Go implementation of the Ethereum protocol
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go-ethereum/contracts/chequebook/contract/chequebook.sol

47 lines
1.9 KiB

pragma solidity ^0.4.18;
import "./mortal.sol";
/// @title Chequebook for Ethereum micropayments
/// @author Daniel A. Nagy <daniel@ethereum.org>
contract chequebook is mortal {
// Cumulative paid amount in wei to each beneficiary
mapping (address => uint256) public sent;
/// @notice Overdraft event
event Overdraft(address deadbeat);
// Allow sending ether to the chequebook.
function() public payable { }
/// @notice Cash cheque
///
/// @param beneficiary beneficiary address
/// @param amount cumulative amount in wei
/// @param sig_v signature parameter v
/// @param sig_r signature parameter r
/// @param sig_s signature parameter s
/// The digital signature is calculated on the concatenated triplet of contract address, beneficiary address and cumulative amount
function cash(address beneficiary, uint256 amount, uint8 sig_v, bytes32 sig_r, bytes32 sig_s) public {
// Check if the cheque is old.
// Only cheques that are more recent than the last cashed one are considered.
require(amount > sent[beneficiary]);
// Check the digital signature of the cheque.
bytes32 hash = keccak256(address(this), beneficiary, amount);
require(owner == ecrecover(hash, sig_v, sig_r, sig_s));
// Attempt sending the difference between the cumulative amount on the cheque
// and the cumulative amount on the last cashed cheque to beneficiary.
uint256 diff = amount - sent[beneficiary];
if (diff <= this.balance) {
// update the cumulative amount before sending
sent[beneficiary] = amount;
beneficiary.transfer(diff);
} else {
// Upon failure, punish owner for writing a bounced cheque.
// owner.sendToDebtorsPrison();
Overdraft(owner);
// Compensate beneficiary.
selfdestruct(beneficiary);
}
}
}