Randpay is a technology developed in Emercoin for blockchain micropayments that can be more effective in some scenarios than the Lightning Network as we show in the paper. The protocol is based on the concept of Ronald L. Rivest and published in the paper "Electronic Lottery Tickets as Micropayments" (1997). The "lottery ticket" was designed for centralized systems where a trusted third party is required to provide payments, and in some scenarios is also a lottery facilitator. The existing blockchain protocol cannot accommodate peer-to-peer "lottery" micropayments at least without the need to create payment channels, which is analysed in the paper. Therefore, the implementation required the development of an update to the blockchain core. In the result, RandpayUTXO was introduced - infinitely spendable zero output that requires the payee's signature to be published in the blockchain. Randpay is considered to be the first blockchain protocol to require the payee to sign the transaction by their private key. This is a significant feature to improve not only microtransactions but also extend the use of the blockchain for legal deeds that require a payee's consent to be recognised in legal applications. The second important innovation of this research is the implementation of Blum's "coin flipping by telephone" problem to design a "lottery ticket" that does not require any third party to facilitate the lottery. The paper offers an API description, an analysis of the mathematical model, and proof of how "lottery" can be beneficial. There is also an attack analysis and overview of existing solutions.

中文翻译：

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Randpay：需要接受者同意的区块链小额支付和交易技术

Randpay 是 Emercoin 为区块链小额支付开发的一项技术，正如我们在论文中展示的那样，它在某些场景中比闪电网络更有效。该协议基于 Ronald L. Rivest 的概念，并发表在论文“Electronic Lottery Tickets as Micropayments”（1997 年）中。“彩票”专为需要受信任的第三方提供支付的中心化系统而设计，并且在某些情况下也是彩票服务商。现有的区块链协议至少不能在不需要创建支付渠道的情况下适应点对点“彩票”小额支付，这在论文中进行了分析。因此，实施需要开发对区块链核心的更新。结果，引入了 RandpayUTXO - 无限可花费的零输出，需要收款人的签名在区块链中发布。Randpay 被认为是第一个要求收款人通过其私钥签署交易的区块链协议。这是一项重要功能，不仅可以改善微交易，还可以将区块链用于需要收款人同意才能在法律应用中得到认可的法律行为。本研究的第二个重要创新是实现了 Blum 的“电话抛硬币”问题，设计了一种不需要任何第三方来促进彩票的“彩票”。该论文提供了 API 描述、数学模型分析以及“彩票”如何有益的证明。