A simplified scheme for secure offline electronic payment systems

• Main Authors: Md. Abdullah Al Rahat Kutubi, Kazi Md. Rokibul Alam, Yasuhiko Morimoto
• Format: Article
• Language: English
• Published: Elsevier 2021-12-01
• Series: High-Confidence Computing
• Subjects: Offline electronic payment; Schnorr's blind signature; RSA algorithm; Zero-knowledge proof; Untraceability
• Online Access: http://www.sciencedirect.com/science/article/pii/S2667295221000210

This paper proposes a secure offline electronic (e-) payment scheme by adopting Schnorr's untraceable blind signature (BS). Thereby, to satisfy the essential security requirements of e-payment systems, it requires much more simple computations and becomes more practical than many existing schemes. Other considerations are: to prevent the forgery of e-coin, the Bank is only the lawful entity to produce the valid e-coin; and others can verify its correctness. To confirm no swindling, the e-coin owner also sticks her private signing key with the e-coin before spending it as the payment. Hence, through the commitment with challenge-response of Schnorr's BS, the merchant can verify the spent e-coin, and the trusted authority can identify the dishonest spender if multiple spending occurs. Moreover, it embeds three distinct information of date, namely expiration, deposit, and transaction dates with every e-coin. Thereby, it minimizes the size of the Bank's database, correctly calculates the interest of the e-coin, and helps in arbiter if multiple spending, respectively. Finally, it evaluates the performance and analyzes essential security requirements of the proposed scheme, plus studies a comparison with existing ones.