This effort expands on provably anonymous electronic cash systems. The trustees can answer the question of whether a particular payment was made by a particular user, without revealing any additional information. This allows for authorized forward and backward tracing that does not impinge on the privacy of anyone other than the parties of the one transaction in question.
Electronic cash is a subject of great economic, political, and research importance.
With advances in computer networks, in processor speed, and in databases, and with advances in note counterfeiting technology and with both individuals' and businesses' desire for remote and more convenient financial transactions, some forms of electronic cash are likely to become widespread within 5 to 10 years. Although unconditionally anonymous electronic cash systems have been proposed in the literature, governmental and financial institutions are unwilling to back a completely anonymous system. Their reasons for opposing complete untraceability have to do with the containment of user fraud and the desire to restrict the new kinds of crime that unrestricted, remotely withdrawable, and spendable electronic cash could facilitate. Because of the necessary concern over crime control, they have previously proposed systems with little or no protection for the users' privacy. Our system provides the capability required by government for crime control while maintaining privacy for all other users.