A new transferable digital cash protocol using proxy re-signature scheme

Abstract

Electronic payment systems have turned out to be a smart and convenient way of making payments. Digital cash is an electronic payment system which is modeled after our real cash system. If the digital cash is transferable then it allows the user to spend an e-coin received in a prior payment immediately without having to contact the bank, that is, the bank remains off-line. In the previous digital cash systems which supported transferability, the digital cash size was growing with each transaction. In this paper, we propose a new digital cash protocol which uses a Forward-Secure Multi-use Unidirectional Proxy Re-signature Scheme to achieve transferability, without any increase in the digital cash size with each transfer. Our scheme enables a secure off-line transaction, thus enforcing user anonymity and transferability. A Trusted Third Party is used to prevent the double spending of the digital coins. © 2011 Springer-Verlag.