A realistic divisible transferable electronic cash for general use
Israt Jahan, Mohammad Zahidur Rahman · Journal of Discrete Mathematical Sciences and Cryptography · 2007
An elegant and probably new divisible transferable anonymous electronic cash system with observer is proposed in this paper. The proposed divisible e-cash solves most of the crucial problem with existing paper cash and untraceable e-cash proposals. Electronic cash provides unconditional anonymity to the user. Researchers observed, however, that if anonymity in payment systems is unconditional, it might be exploited to facilitate crimes like money laundering. This observation spurred research into the idea of making anonymity in payment systems conditional, and, in particular, revocable by a third party or trustee or observer under bank’s order. An observer is a tamper resistant device that prevents doublespending physically. The user module is called a wallet since, it actually carries money. The idea of having an observer is that it can be incorporated in the wallet in such a way that no user module can do a transaction on its own. For any transaction protocol to be executed by the wallet, it needs help (a secret information) from the observer. The advantage of the proposed electronic cash system is that it is able to construct an observer capable of co-operating with divisible and transferable e-cash. A user who generates a divisible coin can transfer his any divisible amount of e-cash to another user and to a number of users subsequently without losing anonymity and without contacting the bank between the two transactions. Due to the presence of observer, the proposed e-cash has prior resistance of double spending. In each transfer of divisible e-cash, coin authentication and denomination revelation is checked to verify the validity of divisible e-cash. In any stage of coin transfer, the anonymity is guaranteed with protection of double spending.