论文标题
与比特币申请的量子审慎合约
Quantum Prudent Contracts with Applications to Bitcoin
论文作者
论文摘要
智能合约是无司法机构执行的加密协议。智能合约偶尔在比特币中使用，并且在以太坊中很普遍。公共量子资金可以改善我们今天使用的现金，但是当前的结构不能实现智能合约。在这项工作中，我们定义和介绍量子支付方案，并展示如何实施审慎的合同 - 以太坊等网络提供的功能的非平凡子集。讨论的示例包括：多签名钱包，其中3个所有者都可以花费资金；只能向指定目的地发送资金的限制帐户；和“彩色硬币”可以代表可以自由交易的股票，其所有者将获得股息。我们的方法不像以太坊中使用的方法那样普遍，因为我们没有就账本状态达成共识。我们称我们的提案谨慎合同来反映这一点。 主构建块是用于数字签名的量子令牌（Ben-David和Sattath Qcrypt'17，Coladangelo等人的CraDangelo等人Crypto'21），用于数字签名的半Quantum令牌（Shmueli'22）或一声签名（Amos等人（Amos等）。该解决方案具有公共量子资金的所有好处：无需采矿，安全模型是标准的（例如，它不容易受到51 \％攻击的影响，如比特币中的攻击）。 我们的单次签名结构可用于将比特币网络升级到量子支付方案。这种方法的显着优势是：交易是可局部可验证的，没有延迟，吞吐量是无限的，最重要的是，它将消除对比特币挖掘的需求。我们的方法需要通用的大型量子计算机和长期量子记忆。因此，我们期望它在未来几年内将无法实施。
Smart contracts are cryptographic protocols that are enforced without a judiciary. Smart contracts are used occasionally in Bitcoin and are prevalent in Ethereum. Public quantum money improves upon cash we use today, yet the current constructions do not enable smart contracts. In this work, we define and introduce quantum payment schemes, and show how to implement prudent contracts -- a non-trivial subset of the functionality that a network such as Ethereum provides. Examples discussed include: multi-signature wallets in which funds can be spent by any 2-out-of-3 owners; restricted accounts that can send funds only to designated destinations; and "colored coins" that can represent stocks that can be freely traded, and their owner would receive dividends. Our approach is not as universal as the one used in Ethereum since we do not reach a consensus regarding the state of a ledger. We call our proposal prudent contracts to reflect this. The main building block is either quantum tokens for digital signatures (Ben-David and Sattath QCrypt'17, Coladangelo et al. Crypto'21), semi-quantum tokens for digital signatures (Shmueli'22) or one-shot signatures (Amos et al. STOC'20). The solution has all the benefits of public quantum money: no mining is necessary, and the security model is standard (e.g., it is not susceptible to 51\% attacks, as in Bitcoin). Our one-shot signature construction can be used to upgrade the Bitcoin network to a quantum payment scheme. Notable advantages of this approach are: transactions are locally verifiable and without latency, the throughput is unbounded, and most importantly, it would remove the need for Bitcoin mining. Our approach requires a universal large-scale quantum computer and long-term quantum memory; hence we do not expect it to be implementable in the next few years.
