Reuse Voided Receipt IDs

reuse-voided-receipt-ids · receipt-attestation · 1491 B runtime · registry-info

scores

• usefulness: 90
• safety: 80
• liveness: 90
• authenticity: 90
• extensibility: 60
• bytecodeDiscipline: 100
• practical: 86

source

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.13;

contract AckOnlyReceipt {
    address private immutable attester;

    struct Receipt {
        bytes32 hash;
        address beneficiary;
        uint64 deadline;
        bool acknowledged;
    }

    mapping(bytes32 => Receipt) private receipts;

    event Attest(bytes32 indexed id, bytes32 hash, address beneficiary, uint64 deadline);
    event Acknowledge(bytes32 indexed id);
    event Void(bytes32 indexed id);

    constructor() {
        attester = msg.sender;
    }

    function attest(bytes32 id, bytes32 hash, address beneficiary, uint64 deadline) external {
        require(msg.sender == attester, "not attester");
        require(receipts[id].beneficiary == address(0), "exists");
        require(beneficiary != address(0), "zero beneficiary");
        require(deadline > block.timestamp, "deadline past");
        receipts[id] = Receipt(hash, beneficiary, deadline, false);
        emit Attest(id, hash, beneficiary, deadline);
    }

    function acknowledge(bytes32 id) external {
        Receipt storage r = receipts[id];
        require(msg.sender == r.beneficiary, "not beneficiary");
        require(!r.acknowledged, "acknowledged");
        require(block.timestamp <= r.deadline, "expired");
        r.acknowledged = true;
        emit Acknowledge(id);
    }

    function void(bytes32 id) external {
        require(msg.sender == attester, "not attester");
        Receipt storage r = receipts[id];
        require(r.beneficiary != address(0), "missing");
        require(!r.acknowledged, "acknowledged");
        r.beneficiary = address(0);
        emit Void(id);
    }
}