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