The main advantages electronic cash systems over other electronic payment systems are its bearing the characteristics of normal paper-based cash systems, i.e. the offline payment and the anonymity of the client (user). However, the anonymity property may be misused for illegal purpose where the signed code delivered to the client could be cloned by such client to be spent in multi-payment processes “double spending”. The proposed schemes of such electronic cash system, started in 1988, failed to be the main e-payment model for e-commerce because none of these schemes could reach a solution to prevent the cloning during the payment process. This book offered a scheme that is capable of solving such problem by combining hardware and software technologies, represented by optical memory card (OMC) and mobile agent technology respectively.