Randpay: The Technology for Blockchain Micropayments and Transactions Which Require Recipient's Consent

Abstract

Randpay is a technology developed in Emercoin for blockchain micropayments that can be more effective in some scenarios than the Lightning Network, as seen in the paper. The protocol is based on the concept of Ronald L. Rivest 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 creating payment channels. Therefore, the implementation requires the development of an upgrade to the blockchain core. In the result, RandpayUTXO was introduced – an 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 recognized 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 analysis of the mathematical model, and proof of how ‘lottery’ can be beneficial, an API description is also added. There is also an attack analysis and an overview of existing solutions.