Proof-of-watch liveness attestation

proof-of-watch-liveness-attestation · receipt-attestation · 705 B runtime · registry-info

scores

• usefulness: 8
• safety: 10
• liveness: 10
• authenticity: 9
• extensibility: 7
• bytecodeDiscipline: 9
• practical: 9

source

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

contract WatchReceipt {
    struct Receipt {
        uint256 blockNumber;
        bytes32 blockHash;
        bytes32 attestationHash;
    }

    mapping(address => Receipt) public receipts;

    event Attested(address indexed account, uint256 blockNumber, bytes32 blockHash, bytes32 attestationHash);

    function attest(uint256 blockNumber, bytes32 attestationHash) external {
        require(blockNumber < block.number, 'block must be in the past');
        require(block.number - blockNumber <= 256, 'blockhash window expired');
        bytes32 h = blockhash(blockNumber);
        require(h != bytes32(0), 'blockhash unavailable');

        receipts[msg.sender] = Receipt(blockNumber, h, attestationHash);
        emit Attested(msg.sender, blockNumber, h, attestationHash);
    }
}