plugeth/contracts/chequebook/contract/chequebook.sol

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import "mortal";
/// @title Chequebook for Ethereum micropayments
/// @author Daniel A. Nagy <daniel@ethdev.com>
contract chequebook is mortal {
// Cumulative paid amount in wei to each beneficiary
mapping (address => uint256) public sent;
/// @notice Overdraft event
event Overdraft(address deadbeat);
/// @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) {
// Check if the cheque is old.
// Only cheques that are more recent than the last cashed one are considered.
if(amount <= sent[beneficiary]) return;
// Check the digital signature of the cheque.
bytes32 hash = sha3(address(this), beneficiary, amount);
if(owner != ecrecover(hash, sig_v, sig_r, sig_s)) return;
// Attempt sending the difference between the cumulative amount on the cheque
// and the cumulative amount on the last cashed cheque to beneficiary.
if (amount - sent[beneficiary] >= this.balance) {
// update the cumulative amount before sending
sent[beneficiary] = amount;
if (!beneficiary.send(amount - sent[beneficiary])) {
// Upon failure to execute send, revert everything
throw;
}
} else {
// Upon failure, punish owner for writing a bounced cheque.
// owner.sendToDebtorsPrison();
Overdraft(owner);
// Compensate beneficiary.
suicide(beneficiary);
}
}
}