A Privacy Enhanced Transferable Electronic Checkbook Scheme

Electronic check (e-check) was first introduced by Chaum in 1990. Afterwards, electronic checkbook (e-checkbook) mechanisms are proposed to eliminate the need to follow a protocol jointly with the bank for each e-check issuance. Despite the fact that the total amount of payments made with checks is high and the processing times of the checks are considerably long, there are not many attempts in the literature regarding the electronic checkbook design. Very recently, most of the previously proposed e-checkbook schemes are shown to be broken by Sertkaya and Kalkar. The one that is not broken, unfortunately, does not satisfy e-check transferability and anonymity properties. In this study, we propose an e-checkbook scheme that supports transferable e-checks and satisfies anonymity property against eavesdropper. More concretely, we first provide game-based security definitions for e-checkbook unforgeability, e-check unforgeability and non-manipulability, and e-check anonymity. After describing the details of the proposed scheme that is based on a signcryption scheme, we prove that our scheme satisfies aforementioned properties along with resistance against double spending and replay attacks. We further discuss computational costs and possible extensions to suit check related legal frameworks.