RemittanceManager.sol

pragma solidity 0.4.15;

contract RemittanceManager {
    struct Remittance {
        address funder;
        address collector;
        uint amount;
        bytes32 combinedPassword;
    }
    
    address owner;
    mapping(uint => Remittance) public remittances; // key is the remittance ID
    uint public count = 0;
    
    function RemittanceManager() {
        owner = msg.sender;
    }
    
    // creates a remittance
    // combinedPassword is sha3(sha3(clearPassword), collector)
    // returns the ID of the remittance
    function create(address collector, bytes32 combinedPassword) payable returns (uint id) {
        require(msg.value > 0);
        id = count;
        remittances[id] = Remittance(msg.sender, collector, msg.value, combinedPassword);
        count++;
    }
    
    // collects a remittance
    // hashedPassword is sha3(clearPassword)
    function collect(uint id, bytes32 hashedPassword) {
        Remittance storage remit = remittances[id];
        require(remit.amount > 0); // the remittance with the ID must exist
        require(remit.collector == msg.sender);
        require(remit.combinedPassword == sha3(hashedPassword, msg.sender));
        uint amountToSend = remit.amount;
        remit.amount = 0;
        msg.sender.transfer(amountToSend);
    }
}