Practical escrow cash systems

Abstract

This paper proposes practical escrow cash schemes with the following properties: The privacy of users is preserved, unless all (or a certain portion) of the trustees collaborate. - If all (or a certain portion) of the trustees collaborate (for law enforcement or crime prevention), the collaboration can trace the payment history from the payer's (i.e., criminal's) name, and they can also trace the payer's (i.e., criminal's) name from a payment history. - Extortion attacks can be partially technically prevented. - Each coin is divisible under an off-fine payment condition.