Transferable channels for fair micropurchases

Abstract The development of e-commerce applications for small-value transactions introduces significant security and privacy challenges. Micropurchases, that is, commercial operations involving micropayments, offer a practical solution that balances efficiency and security for these transactions. The increasing demand for this payment approach, especially with technologies such as the Internet of Things (IoT), highlights the need for innovative solutions. This paper presents a novel micropurchase protocol utilizing a new type of channels, termed transferable payment channels. The proposed protocol, managed through smart contracts, facilitates fair and equitable exchanges between minimal monetary units ( $$\mu $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>μ</mml:mi> </mml:math> -coins) and desired goods or services, enabling efficient low-value payments. Transferable payment channels enable off-chain transactions, reducing the reliance on on-chain transactions to achieve essential security features and ensure fair exchanges without a centralized intermediary or Trusted Third Party (TTP), commonly employed in traditional payment systems. The protocol outlines the processes for making purchases, handling payments, and incorporating functionalities for the transfer and reuse of payment channels by both customers and merchants. Additionally, it specifies procedures for merchants to redeem earned $$\mu $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>μ</mml:mi> </mml:math> -coins and for customers to refund unused $$\mu $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>μ</mml:mi> </mml:math> -coins. This comprehensive set of functions makes the protocol fully functional and highly efficient for micropurchases. By introducing transferable payment channels and minimizing reliance on centralized intermediaries, this work significantly advances the security and efficiency of micropayment systems. The proposed protocol has been implemented and analyzed for both security and performance.