An Anonymous Off-Blockchain Micropayments Scheme for Cryptocurrencies in the Real World

Blockchain, as a secured, trusted, and decentralized architecture, is used to create secure and tamper-proof payment schemes, which can serve economies and societies without trusted parties. However, the transparency and traceability of blockchain severely restrict the anonymity of participants in the real world, which will cause participants’ privacy leakage. Toward this end, in this paper, an anonymous off-blockchain micropayments scheme (AOM) is proposed for cryptocurrencies in the real world. In AOM, a payee receives micropayments from an “honest-but-curious” intermediary <inline-formula> <tex-math notation="LaTeX">${\mathcal {T}}$ </tex-math></inline-formula> by solving puzzles which are generated based on the standard RSA assumption. Meanwhile, <inline-formula> <tex-math notation="LaTeX">${\mathcal {T}}$ </tex-math></inline-formula> also receives micropayments from the payers by payee’s solutions and <inline-formula> <tex-math notation="LaTeX">${\mathcal {T}}$ </tex-math></inline-formula> will randomly select the inputs of the merging transaction <inline-formula> <tex-math notation="LaTeX">${T}_{\text {mer}}$ </tex-math></inline-formula>. In order to improve service efficiency of <inline-formula> <tex-math notation="LaTeX">${\mathcal {T}}$ </tex-math></inline-formula> and resist denial of service attack, one of the outputs of <inline-formula> <tex-math notation="LaTeX">${T}_{\text {mer}}$ </tex-math></inline-formula> is paid for <inline-formula> <tex-math notation="LaTeX">${\mathcal {T}}$ </tex-math></inline-formula> as a service fee. Besides, AOM simultaneously ensures the correctness and fairness of transactions. Finally, from the analyses of property and security, AOM has strong unlinkability, ability for anti-attacks and unforgeability.