An Offline Electronic Payment System Based on an Untraceable Blind Signature Scheme. - Md. Abdullah Al Rahat Kutubi; Kazi Md. Rokibul Alam; Rafaf Tahsin; G. G. Md. Nawaz Ali; Peter Han Joo Chong; Yasuhiko Morimoto (KSII Trans. Internet Inf. Syst., 2017)